/**
 * @module 3D
 * @submodule p5.strands
 * @for p5
 */

import * as constants from '../core/constants';
import { getStrokeDefs } from '../webgl/enums';
import { DataType, INSTANCE_ID_VARYING_NAME } from '../strands/ir_types.js';

import { colorVertexShader, colorFragmentShader } from './shaders/color';
import { lineVertexShader, lineFragmentShader} from './shaders/line';
import { materialVertexShader, materialFragmentShader } from './shaders/material';
import { fontVertexShader, fontFragmentShader } from './shaders/font';
import { blitVertexShader, blitFragmentShader } from './shaders/blit';
import { wgslBackend } from './strands_wgslBackend';

import { baseFilterVertexShader, baseFilterFragmentShader } from './shaders/filters/base';
import { imageLightVertexShader, imageLightDiffusedFragmentShader, imageLightSpecularFragmentShader } from './shaders/imageLight';
import { baseComputeShader } from './shaders/compute';

const FRAME_STATE = {
  PENDING: 0,
  UNPROMOTED: 1,
  PROMOTED: 2
};

function rendererWebGPU(p5, fn) {
  const { lineDefs } = getStrokeDefs((n, v, t) => `const ${n}: ${t} = ${v};\n`);

  // RendererWebGPU depends on these other classes being set up prior,
  // as it is optimized for being in a standalone build, not core
  const {
    Renderer3D,
    Shader,
    Texture,
    MipmapTexture,
    Image,
    Camera,
    RGBA,
  } = p5;

  class StorageBuffer {
    constructor(buffer, size, renderer, schema = null) {
      this._isStorageBuffer = true;
      this.buffer = buffer;
      this.size = size;
      this._renderer = renderer;
      this._schema = schema;
    }

    /**
     * Updates the data in the buffer with new values. The new data must be in
     * the same format as the data originally passed to
     * <a href="#/p5/createStorage">`createStorage()`</a>.
     *
     * ```js example
     * let particles;
     * let computeShader;
     * let displayShader;
     * const numParticles = 100;
     *
     * async function setup() {
     *   await createCanvas(100, 100, WEBGPU);
     *   particles = createStorage(makeParticles(width / 2, height / 2));
     *   computeShader = buildComputeShader(simulate);
     *   displayShader = buildMaterialShader(display);
     *   describe('100 orange particles shooting outward.');
     * }
     *
     * function makeParticles(x, y) {
     *   let data = [];
     *   for (let i = 0; i < numParticles; i++) {
     *     let angle = (i / numParticles) * TWO_PI;
     *     let speed = random(0.5, 2);
     *     data.push({
     *       position: createVector(x, y),
     *       velocity: createVector(cos(angle) * speed, sin(angle) * speed),
     *     });
     *   }
     *   return data;
     * }
     *
     * function simulate() {
     *   let data = uniformStorage(particles);
     *   let idx = index.x;
     *   data[idx].position = data[idx].position + data[idx].velocity;
     * }
     *
     * function display() {
     *   let data = uniformStorage(particles);
     *   worldInputs.begin();
     *   let pos = data[instanceIndex].position;
     *   worldInputs.position.xy += pos - [width / 2, height / 2];
     *   worldInputs.end();
     * }
     *
     * function draw() {
     *   background(30);
     *   if (frameCount % 60 === 0) {
     *     particles.update(makeParticles(random(width), random(height)));
     *   }
     *   compute(computeShader, numParticles);
     *   noStroke();
     *   fill(255, 200, 50);
     *   shader(displayShader);
     *   instances(numParticles).sphere(2);
     * }
     * ```
     *
     * @method update
     * @for p5.StorageBuffer
     * @beta
     * @webgpu
     * @webgpuOnly
     * @param {Number[]|Float32Array|Object[]} data The new data to write into the buffer.
     */
    update(data) {
      const device = this._renderer.device;

      if (this._schema !== null) {
        // Buffer was created with a struct array
        if (
          !Array.isArray(data) ||
          data.length === 0 ||
          typeof data[0] !== 'object' ||
          Array.isArray(data[0])
        ) {
          throw new Error(
            'update() expects an array of objects matching the original struct format'
          );
        }

        const newSchema = this._renderer._inferStructSchema(data[0]);
        if (newSchema.structBody !== this._schema.structBody) {
          throw new Error(
            `update() data structure doesn't match the original.\n` +
            `  Expected: ${this._schema.structBody}\n` +
            `  Got:      ${newSchema.structBody}`
          );
        }

        const packed = this._renderer._packStructArray(data, this._schema);
        if (packed.byteLength > this.size) {
          throw new Error(
            `update() data (${packed.byteLength} bytes) exceeds buffer size (${this.size} bytes)`
          );
        }
        device.queue.writeBuffer(this.buffer, 0, packed);
      } else {
        // Buffer was created with a float array
        let floatData;
        if (data instanceof Float32Array) {
          floatData = data;
        } else if (Array.isArray(data)) {
          floatData = new Float32Array(data);
        } else {
          throw new Error(
            'update() expects a Float32Array or array of numbers for this buffer'
          );
        }

        if (floatData.byteLength > this.size) {
          throw new Error(
            `update() data (${floatData.byteLength} bytes) exceeds buffer size (${this.size} bytes)`
          );
        }
        device.queue.writeBuffer(this.buffer, 0, floatData);
      }
    }

    /**
     * Reads data from a storage buffer back into JavaScript.
     *
     * Copies data from the GPU to the CPU using a temporary buffer,
     * so it must be awaited. Returns a `Float32Array` for number
     * buffers, or an array of plain objects for struct buffers.
     *
     * Note: This is a GPU -> CPU read, so calling it often (like every frame)
     * can be slow.
     *
     * ```js example
     * let data;
     * let computeShader;
     *
     * async function setup() {
     *   await createCanvas(100, 100, WEBGPU);
     *
     *   data = createStorage(new Float32Array([1, 2, 3, 4]));
     *   computeShader = buildComputeShader(doubleValues);
     *   compute(computeShader, 4);
     *
     *   let result = await data.read();
     *   // result is Float32Array [2, 4, 6, 8]
     *   for (let i = 0; i < result.length; i++) {
     *     print(result[i]);
     *   }
     *   describe('Prints the values 2, 4, 6, 8 to the console.');
     * }
     *
     * function doubleValues() {
     *   let d = uniformStorage(data);
     *   let idx = index.x;
     *   d[idx] = d[idx] * 2;
     * }
     * ```
     *
     * @method read
     * @for p5.StorageBuffer
     * @beta
     * @webgpu
     * @webgpuOnly
     * @returns {Promise<Float32Array|Object[]>}
     */
    async read() {
      const device = this._renderer.device;
      this._renderer.flushDraw();

      const stagingBuffer = device.createBuffer({
        size: this.size,
        usage: GPUBufferUsage.COPY_DST | GPUBufferUsage.MAP_READ,
      });

      const commandEncoder = device.createCommandEncoder();
      commandEncoder.copyBufferToBuffer(this.buffer, 0, stagingBuffer, 0, this.size);
      device.queue.submit([commandEncoder.finish()]);

      await stagingBuffer.mapAsync(GPUMapMode.READ, 0, this.size);
      const mappedRange = stagingBuffer.getMappedRange(0, this.size);

      // Copy before unmapping because mapped memory becomes invalid after unmap
      const rawCopy = new Float32Array(mappedRange.byteLength / 4);
      rawCopy.set(new Float32Array(mappedRange));

      stagingBuffer.unmap();
      stagingBuffer.destroy();

      if (this._schema !== null) {
        return this._renderer._unpackStructArray(rawCopy, this._schema);
      }
      return rawCopy;
    }

    /**
     * Updates a single element in the buffer at a given index. Use this
     * when only a small number of elements need to change. If you need to
     * replace all the data at once, use
     * <a href="#/p5.StorageBuffer/update">`update()`</a> instead.
     *
     * ```js
     * let buf;
     *
     * async function setup() {
     *   await createCanvas(100, 100, WEBGPU);
     *
     *   // Float buffer: update one value by index
     *   buf = createStorage(new Float32Array([1, 2, 3, 4]));
     *   buf.set(2, 9.5); // only index 2 changes → [1, 2, 9.5, 4]
     *
     *   let result = await buf.read();
     *   print(result[2]); // 9.5
     *   describe('Prints 9.5 to the console.');
     * }
     * ```
     *
     * ```js
     * let particles;
     * const numParticles = 100;
     *
     * async function setup() {
     *   await createCanvas(100, 100, WEBGPU);
     *   particles = createStorage(makeParticles());
     *
     *   // Replace particle 42 without touching the others
     *   particles.set(42, {
     *     position: createVector(0, 0),
     *     velocity: createVector(1, 0),
     *   });
     *
     *   // Read back to confirm the update
     *   let result = await particles.read();
     *   print(result[42].position.x, result[42].position.y); // 0, 0
     *   describe('Prints the position of particle 42 after updating it.');
     * }
     *
     * function makeParticles() {
     *   let data = [];
     *   for (let i = 0; i < numParticles; i++) {
     *     data.push({
     *       position: createVector(random(width), random(height)),
     *       velocity: createVector(random(-1, 1), random(-1, 1)),
     *     });
     *   }
     *   return data;
     * }
     * ```
     *
     * @method set
     * @for p5.StorageBuffer
     * @beta
     * @webgpu
     * @webgpuOnly
     * @param {Number} index The zero-based index of the element to update.
     * @param {Number|Object} value The new value. Pass a number for float
     *   buffers, or a plain object matching the original struct layout for
     *   struct buffers.
     */
    set(index, value) {
      const device = this._renderer.device;

      if (this._schema !== null) {
        // buffer was created with an array of structs
        if (typeof value !== 'object' || value === null || Array.isArray(value)) {
          throw new Error(
            'set() expects a plain object matching the original struct format for this buffer'
          );
        }

        const { stride } = this._schema;
        const byteOffset = index * stride;

        if (byteOffset + stride > this.size) {
          throw new Error(
            `set() index ${index} is out of bounds for this buffer ` +
            `(buffer holds ${Math.floor(this.size / stride)} elements)`
          );
        }

        // pack just this one element using the same logic as update()
        const packed = this._renderer._packStructArray([value], this._schema);
        // use packed.buffer (ArrayBuffer) so the size arg is always in bytes
        device.queue.writeBuffer(this.buffer, byteOffset, packed.buffer, 0, stride);
      } else {
        // buffer was created with a float array
        if (typeof value !== 'number') {
          throw new Error(
            'set() expects a number for this float buffer'
          );
        }

        const byteOffset = index * 4;

        if (byteOffset + 4 > this.size) {
          throw new Error(
            `set() index ${index} is out of bounds for this buffer ` +
            `(buffer holds ${Math.floor(this.size / 4)} floats)`
          );
        }

        device.queue.writeBuffer(this.buffer, byteOffset, new Float32Array([value]));
      }
    }
  }

  /**
   * A block of data that shaders can read from, and compute shaders can also
   * write to. This is only available in WebGPU mode.
   *
   * Note: <a href="#/p5/createStorage">`createStorage()`</a> is the recommended
   * way to create an instance of this class.
   *
   * @class p5.StorageBuffer
   * @beta
   * @webgpu
   * @webgpuOnly
   */
  p5.StorageBuffer = StorageBuffer;

  class RendererWebGPU extends Renderer3D {
    constructor(pInst, w, h, isMainCanvas, elt) {
      super(pInst, w, h, isMainCanvas, elt)

      // Used to group draws into one big render pass
      this.activeRenderPass = null;
      this.activeRenderPassEncoder = null;
      this.activeShaderOptions = null;
      this.activeShader = null;

      this.samplers = new Map();

      // Some uniforms update every frame, like model matrices and sometimes colors.
      // The fastest way to handle these is to use mapped memory. We'll batch those
      // into bigger buffers with dynamic offsets, separate from the usual system
      // where bind groups have their own little buffers that get cached when they
      // are unchanged
      this.uniformBufferAlignment = 256;
      this.activeUniformBuffers = [];
      this.currentUniformBuffer = undefined;
      this.uniformBufferPool = [];
      this.resettingUniformBuffers = [];

      this.dynamicEntryOffsets = new Uint32Array(64);

      // Cache for current frame's canvas texture view
      this.currentCanvasColorTexture = null;
      this.currentCanvasColorTextureView = null;

      // Single reusable staging buffer for pixel reading
      this.pixelReadBuffer = null;
      this.pixelReadBufferSize = 0;

      this.strandsBackend = wgslBackend;

      // Registry to track all shaders for uniform data pooling
      this._shadersWithPools = [];

      // Registry to track geometries with buffer pools
      this._geometriesWithPools = [];

      // Flag to track if any draws have happened that need queue submission
      this._hasPendingDraws = false;
      this._pendingCommandEncoders = [];

      // Queue of callbacks to run after next submit (mainly for safe texture deletion)
      this._postSubmitCallbacks = [];

      // Retired buffers to destroy at end of frame
      this._retiredBuffers = [];

      // Storage buffers for compute shaders
      this._storageBuffers = new Set();

      // 2D canvas for pixel reading fallback
      this._pixelReadCanvas = null;
      this._pixelReadCtx = null;
      this.mainFramebuffer = null;
      this._frameState = FRAME_STATE.PENDING;

      this.finalCamera = new Camera(this);
      this.finalCamera._computeCameraDefaultSettings();
      this.finalCamera._setDefaultCamera();

      this.depthFormat = 'depth24plus-stencil8';
      this.depthTexture = null;
      this.depthTextureView = null;
    }

    async setupContext() {
      this._setAttributeDefaults(this._pInst);
      await this._initContext();
    }

    _setAttributeDefaults(pInst) {
      const defaults = {
        forceFallbackAdapter: false,
        powerPreference: 'high-performance',
      };
      if (pInst._webgpuAttributes === null) {
        pInst._webgpuAttributes = defaults;
      } else {
        pInst._webgpuAttributes = Object.assign(defaults, pInst._webgpuAttributes);
      }
      return;
    }

    async _initContext() {
      this.adapter = await navigator.gpu?.requestAdapter(this._webgpuAttributes);
      this.device = await this.adapter?.requestDevice({
        // Todo: check support
        requiredFeatures: ['depth32float-stencil8']
      });
      if (!this.device) {
        throw new Error('Your browser does not support WebGPU.');
      }
      this.queue = this.device.queue;
      this.drawingContext = this.canvas.getContext('webgpu');
      this.presentationFormat = navigator.gpu.getPreferredCanvasFormat();
      this.drawingContext.configure({
        device: this.device,
        format: this.presentationFormat,
        usage: GPUTextureUsage.RENDER_ATTACHMENT | GPUTextureUsage.COPY_SRC,
        alphaMode: 'premultiplied',
      });

      // TODO disablable stencil
      this.mainFramebuffer = this.createFramebuffer({ _useCanvasFormat: true });
      this._updateSize();
      this._update();
      this.flushDraw();
    }

    async _setAttributes(key, value) {
      if (typeof this._pInst._webgpuAttributes === "undefined") {
        console.log(
          "You are trying to use setAttributes on a p5.Graphics object " +
          "that does not use a WebGPU renderer."
        );
        return;
      }
      let unchanged = true;

      if (typeof value !== "undefined") {
        //first time modifying the attributes
        if (this._pInst._webgpuAttributes === null) {
          this._pInst._webgpuAttributes = {};
        }
        if (this._pInst._webgpuAttributes[key] !== value) {
          //changing value of previously altered attribute
          this._pInst._webgpuAttributes[key] = value;
          unchanged = false;
        }
        //setting all attributes with some change
      } else if (key instanceof Object) {
        if (this._pInst._webgpuAttributes !== key) {
          this._pInst._webgpuAttributes = key;
          unchanged = false;
        }
      }
      //@todo_FES
      if (!this.isP3D || unchanged) {
        return;
      }

      if (!this._pInst._setupDone) {
        if (this.geometryBufferCache.numCached() > 0) {
          p5.FES.log`Sorry, Could not set the attributes, you need to call setAttributes() before calling the other drawing methods in setup()`();
          return;
        }
      }

      await this._resetContext(null, null, RendererWebGPU);

      if (this.states.curCamera) {
        this.states.curCamera._renderer = this._renderer;
      }
    }

    _updateSize() {
      if (!this.device || !this.depthFormat) return;
      if (this.depthTexture && this.depthTexture.destroy) {
        this.flushDraw();
        const textureToDestroy = this.depthTexture;
        this._postSubmitCallbacks.push(() => textureToDestroy.destroy());
        this.depthTextureView = null;
      }
      this.depthTexture = this.device.createTexture({
        size: {
          width: Math.ceil(this.width * this._pixelDensity),
          height: Math.ceil(this.height * this._pixelDensity),
          depthOrArrayLayers: 1,
        },
        format: this.depthFormat,
        usage: GPUTextureUsage.RENDER_ATTACHMENT | GPUTextureUsage.COPY_SRC,
      });
      this.depthTextureView = this.depthTexture.createView();

      // Clear the main canvas after resize
      this.clear();
    }

    _getCanvasColorTextureView() {
      const canvasTexture = this.drawingContext.getCurrentTexture();
      // If texture changed (new frame), update cache
      if (this.currentCanvasColorTexture !== canvasTexture) {
        this.currentCanvasColorTexture = canvasTexture;
        this.currentCanvasColorTextureView = canvasTexture.createView();
      }
      return this.currentCanvasColorTextureView;
    }

    _beginActiveRenderPass() {
      if (this.activeRenderPass) return;

      // Use framebuffer texture if active, otherwise use canvas texture
      const activeFramebuffer = this.activeFramebuffer();

      const colorAttachment = {
        view: activeFramebuffer
          ? (activeFramebuffer.aaColorTexture
              ? activeFramebuffer.aaColorTextureView
              : activeFramebuffer.colorTextureView)
          : this._getCanvasColorTextureView(),
        loadOp: "load",
        storeOp: "store",
        // If using multisampled texture, resolve to non-multisampled texture
        resolveTarget: activeFramebuffer && activeFramebuffer.aaColorTexture
          ? activeFramebuffer.colorTextureView
          : undefined,
      };

      // Use framebuffer depth texture if active, otherwise use canvas depth texture
      const depthTextureView = activeFramebuffer
        ? (activeFramebuffer.aaDepthTexture
            ? activeFramebuffer.aaDepthTextureView
            : activeFramebuffer.depthTextureView)
        : this.depthTextureView;
      const renderPassDescriptor = {
        colorAttachments: [colorAttachment],
        depthStencilAttachment: depthTextureView
          ? {
              view: depthTextureView,
              depthLoadOp: "load",
              depthStoreOp: "store",
              depthClearValue: 1.0,
              stencilLoadOp: "load",
              stencilStoreOp: "store",
              depthReadOnly: false,
              stencilReadOnly: false,
            }
          : undefined,
      };
      const commandEncoder = this.device.createCommandEncoder();
      const passEncoder = commandEncoder.beginRenderPass(renderPassDescriptor);
      this.activeRenderPassEncoder = commandEncoder;
      this.activeRenderPass = passEncoder;
    }

    _finishActiveRenderPass() {
      if (!this.activeRenderPass) return;

      const commandEncoder = this.activeRenderPassEncoder;
      const passEncoder = this.activeRenderPass;
      passEncoder.end();

      // Store the command encoder for later submission
      this._pendingCommandEncoders.push(commandEncoder.finish());
      this.activeRenderPassEncoder = null;
      this.activeRenderPass = null;
      this.activeShader = null;
      this.activeShaderOptions = null;
    }

    clear(...args) {
      if (!this.device || !this.drawingContext) return;
      const _r = args[0] || 0;
      const _g = args[1] || 0;
      const _b = args[2] || 0;
      const _a = args[3] || 0;

      // If PENDING and no custom framebuffer, clear means stay UNPROMOTED.
      // However, if we are still in setup (frameCount == 0), we must promote
      // so that mainFramebuffer gets the cleared content. This ensures that if
      // draw() later promotes without a copy, it starts from the correct state
      // rather than a stale mainFramebuffer.
      // Note: a mid-draw-loop transition from UNPROMOTED back to PROMOTED
      // (i.e. calling background() some frames but not others) will still
      // lose intermediate UNPROMOTED frame content.
      if (this._frameState !== FRAME_STATE.PROMOTED && !this.activeFramebuffer()) {
        if (this._pInst.frameCount > 0) {
          this._frameState = FRAME_STATE.UNPROMOTED;
        } else {
          this._promoteToFramebufferWithoutCopy();
          // clear() then targets mainFramebuffer via activeFramebuffer()
        }
      }

      this._finishActiveRenderPass();

      const commandEncoder = this.device.createCommandEncoder();

      // Use framebuffer texture if active, otherwise use canvas texture
      const activeFramebuffer = this.activeFramebuffer();

      const colorAttachment = {
        view: activeFramebuffer
          ? (activeFramebuffer.aaColorTexture
              ? activeFramebuffer.aaColorTextureView
              : activeFramebuffer.colorTextureView)
          : this._getCanvasColorTextureView(),
        clearValue: { r: _r * _a, g: _g * _a, b: _b * _a, a: _a },
        loadOp: 'clear',
        storeOp: 'store',
        // If using multisampled texture, resolve to non-multisampled texture
        resolveTarget: activeFramebuffer && activeFramebuffer.aaColorTexture
          ? activeFramebuffer.colorTextureView
          : undefined,
      };

      // Use framebuffer depth texture if active, otherwise use canvas depth texture
      const depthTextureView = activeFramebuffer
        ? (activeFramebuffer.aaDepthTexture
            ? activeFramebuffer.aaDepthTextureView
            : activeFramebuffer.depthTextureView)
        : this.depthTextureView;
      const depthAttachment = depthTextureView
        ? {
          view: depthTextureView,
          depthClearValue: 1.0,
          depthLoadOp: 'clear',
          depthStoreOp: 'store',
          stencilLoadOp: 'load',
          stencilStoreOp: 'store',
        }
        : undefined;

      const renderPassDescriptor = {
        colorAttachments: [colorAttachment],
        ...(depthAttachment ? { depthStencilAttachment: depthAttachment } : {}),
      };

      const passEncoder = commandEncoder.beginRenderPass(renderPassDescriptor);
      passEncoder.end();

      this._pendingCommandEncoders.push(commandEncoder.finish());
      this._hasPendingDraws = true;
    }

    /**
     * Resets all depth information so that nothing previously drawn will
     * occlude anything subsequently drawn.
     */
    clearDepth(depth = 1) {
      if (!this.device || !this.depthTextureView) return;
      this._finishActiveRenderPass();
      const commandEncoder = this.device.createCommandEncoder();

      // Use framebuffer texture if active, otherwise use canvas texture
      const activeFramebuffer = this.activeFramebuffer();

      // Use framebuffer depth texture if active, otherwise use canvas depth texture
      const depthTextureView = activeFramebuffer
        ? (activeFramebuffer.aaDepthTexture
            ? activeFramebuffer.aaDepthTextureView
            : activeFramebuffer.depthTextureView)
        : this.depthTextureView;

      if (!depthTextureView) {
        // No depth buffer to clear
        return;
      }

      const depthAttachment = {
        view: depthTextureView,
        depthClearValue: depth,
        depthLoadOp: 'clear',
        depthStoreOp: 'store',
        stencilLoadOp: 'load',
        stencilStoreOp: 'store',
      };

      const renderPassDescriptor = {
        colorAttachments: [], // No color attachments, we're only clearing depth
        depthStencilAttachment: depthAttachment,
      };

      const passEncoder = commandEncoder.beginRenderPass(renderPassDescriptor);
      passEncoder.end();

      this._pendingCommandEncoders.push(commandEncoder.finish());
      this._hasPendingDraws = true;
    }

    _prepareBuffer(renderBuffer, geometry, shader) {
      const attr = shader.attributes[renderBuffer.attr];
      if (!attr) return;

      const { src, dst, size, map } = renderBuffer;

      const device = this.device;
      const buffers = this._getOrMakeCachedBuffers(geometry);
      let srcData = geometry[src];
      if (!srcData || srcData.length === 0) {
        if (renderBuffer.default) {
          srcData = geometry[src] = renderBuffer.default(geometry);
          srcData.isDefault = true;
        } else {
          return;
        }
      }

      // Check if we already have a buffer for this data
      let existingBuffer = buffers[dst];
      const needsNewBuffer = !existingBuffer;

      // Only create new buffer and write data if buffer doesn't exist or data is dirty
      if (needsNewBuffer || geometry.dirtyFlags[src] !== false) {
        const raw = map ? map(srcData) : srcData;
        const typed = this._normalizeBufferData(raw, Float32Array);

        // Get pooled buffer (may reuse existing or create new)
        const pooledBufferInfo = this._getVertexBufferFromPool(geometry, dst, typed.byteLength);

        // Create a copy of the data to avoid conflicts when geometry arrays are reset
        const dataCopy = new typed.constructor(typed);
        pooledBufferInfo.dataCopy = dataCopy;

        // Write the data to the pooled buffer
        device.queue.writeBuffer(pooledBufferInfo.buffer, 0, dataCopy);

        // Update the buffers cache to use the pooled buffer
        buffers[dst] = pooledBufferInfo.buffer;
        geometry.dirtyFlags[src] = false;
      }

      shader.enableAttrib(attr, size);
    }

    _disableRemainingAttributes(shader) {}

    _enableAttrib(attr) {
      // TODO: is this necessary?
      const loc = attr.location;
      if (!this.registerEnabled.has(loc)) {
        // TODO
        this.registerEnabled.add(loc);
      }
    }

    _ensureGeometryBuffers(buffers, indices, indexType) {
      if (!indices) return;

      const device = this.device;

      const buffer = device.createBuffer({
        size: Math.ceil((indices.length * indexType.BYTES_PER_ELEMENT) / 4) * 4,
        usage: GPUBufferUsage.INDEX | GPUBufferUsage.COPY_DST,
        mappedAtCreation: true,
      });

      // Write index data to buffer
      const mapping = new indexType(buffer.getMappedRange());
      mapping.set(indices);
      buffer.unmap();

      buffers.indexBuffer = buffer;
      buffers.indexBufferType = indexType === Uint32Array ? 'uint32' : 'uint16';
    }

    _freeBuffers(buffers) {
      const destroyIfExists = (buf) => {
        if (buf && buf.destroy) {
          buf.destroy();
        }
      };

      destroyIfExists(buffers.indexBuffer);

      const freeDefs = (defs) => {
        for (const def of defs) {
          destroyIfExists(buffers[def.dst]);
          buffers[def.dst] = null;
        }
      };

      freeDefs(this.buffers.stroke);
      freeDefs(this.buffers.fill);
      freeDefs(this.buffers.user);
    }

    _getValidSampleCount(requestedCount) {
      // WebGPU supports sample counts of 1, 4 (and sometimes 8)
      if (requestedCount <= 1) return 1;
      if (requestedCount <= 4) return 4;
      return 4; // Cap at 4 for broader compatibility
    }

    _shaderOptions({ mode, compute, workgroupSize }) {
      if (compute) return { compute: true, workgroupSize };
      const activeFramebuffer = this.activeFramebuffer();
      const format = activeFramebuffer ?
        this._getWebGPUColorFormat(activeFramebuffer) :
        this.presentationFormat;

      const requestedSampleCount = activeFramebuffer ?
        (activeFramebuffer.antialias ? activeFramebuffer.antialiasSamples : 1) :
        1;  // No MSAA needed when blitting already-antialiased textures to canvas
      const sampleCount = this._getValidSampleCount(requestedSampleCount);

      const depthFormat = activeFramebuffer
        ? (activeFramebuffer.useDepth ? this._getWebGPUDepthFormat(activeFramebuffer) : undefined)
        : this.depthFormat;

      const drawTarget = this.drawTarget();
      const clipping = this._clipping;
      const clipApplied = drawTarget._isClipApplied;

      return {
        topology: mode === constants.TRIANGLE_STRIP ? 'triangle-strip' : 'triangle-list',
        blendMode: this.states.curBlendMode,
        sampleCount,
        format,
        depthFormat,
        clipping,
        clipApplied,
      }
    }

    _shaderOptionsDifferent(newOptions) {
      if (!this.activeShaderOptions) return true;
      for (const key in this.activeShaderOptions) {
        if (this.activeShaderOptions[key] !== newOptions[key]) return true;
      }
      return false;
    }

    _initShader(shader) {
      const device = this.device;

      if (shader.shaderType === 'compute') {
        // Compute shader initialization
        shader.computeModule = device.createShaderModule({ code: shader.computeSrc() });
        shader._computePipelineCache = null;
        shader._workgroupSize = null;

        // Create compute pipeline (deferred until first compute() call)
        shader.getPipeline = ({ workgroupSize }) => {
          if (!shader._computePipelineCache) {
            shader._computePipelineCache = device.createComputePipeline({
              layout: shader._pipelineLayout,
              compute: {
                module: shader.computeModule,
                entryPoint: 'main'
              }
            });
            shader._workgroupSize = workgroupSize;
          }
          return shader._computePipelineCache;
        };

        return;
      }

      // Render shader initialization
      shader.vertModule = device.createShaderModule({ code: shader.vertSrc() });
      shader.fragModule = device.createShaderModule({ code: shader.fragSrc() });

      shader._pipelineCache = new Map();
      shader.getPipeline = ({ topology, blendMode, sampleCount, format, depthFormat, clipping, clipApplied }) => {
        const key = `${topology}_${blendMode}_${sampleCount}_${format}_${depthFormat}_${clipping}_${clipApplied}`;
        if (!shader._pipelineCache.has(key)) {
          const pipeline = device.createRenderPipeline({
            layout: shader._pipelineLayout,
            vertex: {
              module: shader.vertModule,
              entryPoint: 'main',
              buffers: this._getVertexLayout(shader),
            },
            fragment: {
              module: shader.fragModule,
              entryPoint: 'main',
              targets: [{
                format,
                blend: this._getBlendState(blendMode),
              }],
            },
            primitive: { topology },
            multisample: { count: sampleCount },
            ...(depthFormat ? {
              depthStencil: {
                format: depthFormat,
                depthWriteEnabled: !clipping,
                depthCompare: 'less-equal',
                stencilFront: {
                  compare: clipping ? 'always' : (clipApplied ? 'not-equal' : 'always'),
                  failOp: 'keep',
                  depthFailOp: 'keep',
                  passOp: clipping ? 'replace' : 'keep',
                },
                stencilBack: {
                  compare: clipping ? 'always' : (clipApplied ? 'not-equal' : 'always'),
                  failOp: 'keep',
                  depthFailOp: 'keep',
                  passOp: clipping ? 'replace' : 'keep',
                },
                stencilReadMask: 0xFF,
                stencilWriteMask: clipping ? 0xFF : 0x00,
              },
            } : {}),
          });
          shader._pipelineCache.set(key, pipeline);
        }
        return shader._pipelineCache.get(key);
      }
    }

    _finalizeShader(shader) {
      // Per-group buffer pools. We will pull from these when we draw multiple
      // times using the shader in a render pass. These are per group instead of
      // global so that we can reuse the last used buffer when uniform values
      // don't change.
      shader._uniformBufferGroups = [];
      shader.buffersDirty = new Set();

      for (const group of shader._uniformGroups) {
        // Calculate the size needed for this group's uniforms
        const groupUniforms = Object.values(group.uniforms);
        const rawSize = Math.max(
          0,
          ...groupUniforms.map(u => u.offsetEnd)
        );
        const alignedSize = Math.ceil(rawSize / 16) * 16;

        shader._uniformBufferGroups.push({
          group: group.group,
          binding: group.binding,
          cacheKey: group.group * 1000 + group.binding,
          varName: group.varName,
          structType: group.structType,
          uniforms: groupUniforms,
          size: alignedSize,

          bufferPool: [],
          nextBufferPool: [],

          dynamic: groupUniforms.some(u => u.name.startsWith('uModel')),
          buffersInUse: new Set(),
          currentBuffer: null, // For caching
        });
      }

      // Register this shader in our registry for pool cleanup
      this._shadersWithPools.push(shader);

      const bindGroupLayouts = new Map(); // group index -> bindGroupLayout
      const groupEntries = new Map(); // group index -> array of entries

      // Add all uniform group bindings to group 0
      const structEntries = new Map();
      for (const bufferGroup of shader._uniformBufferGroups) {
        const entries = structEntries.get(bufferGroup.group) || [];
        entries.push({
          bufferGroup,
          binding: bufferGroup.binding,
          visibility: shader.shaderType === 'compute'
            ? GPUShaderStage.COMPUTE
            : GPUShaderStage.VERTEX | GPUShaderStage.FRAGMENT,
          buffer: { type: 'uniform', hasDynamicOffset: bufferGroup.dynamic },
        });
        structEntries.set(bufferGroup.group, entries);
      }
      for (const [group, entries] of structEntries.entries()) {
        entries.sort((a, b) => a.binding - b.binding);
        groupEntries.set(group, entries);
      }

      // Add the variable amount of samplers and texture bindings that can come after
      for (const sampler of shader.samplers) {
        const group = sampler.group;
        const entries = groupEntries.get(group) || [];
        if (!['sampler', 'texture_2d<f32>'].includes(sampler.type)) {
          throw new Error(`Unsupported texture type: ${sampler.type}`);
        }

        entries.push({
          binding: sampler.binding,
          visibility: sampler.visibility,
          sampler: sampler.type === 'sampler'
            ? { type: 'filtering' }
            : undefined,
          texture: sampler.type === 'texture_2d<f32>'
            ? { sampleType: 'float', viewDimension: '2d' }
            : undefined,
          uniform: sampler,
        });

        entries.sort((a, b) => a.binding - b.binding);
        groupEntries.set(group, entries);
      }

      // Add storage buffer bindings
      for (const storage of shader._storageBuffers || []) {
        const group = storage.group;
        const entries = groupEntries.get(group) || [];

        entries.push({
          binding: storage.binding,
          visibility: storage.visibility,
          buffer: {
            type: storage.accessMode === 'read' ? 'read-only-storage' : 'storage'
          },
          storage: storage,
        });

        entries.sort((a, b) => a.binding - b.binding);
        groupEntries.set(group, entries);
      }

      // Create layouts and bind groups
      const groupEntriesArr = [];
      for (const [group, entries] of groupEntries) {
        const layout = this.device.createBindGroupLayout({ entries });
        bindGroupLayouts.set(group, layout);
        groupEntriesArr.push([group, entries]);
      }

      shader._groupEntries = groupEntriesArr;
      shader._bindGroupLayouts = [...bindGroupLayouts.values()];
      // Reuse bind groups if they don't change
      shader._cachedBindGroup = {};
      // Remember which dynamic buffer we last used, so that we can
      // possibly cache bind groups if unchanged
      shader._lastDynamicBuffer = {};
      shader._pipelineLayout = this.device.createPipelineLayout({
        bindGroupLayouts: shader._bindGroupLayouts,
      });
      shader._compiled = true;
    }

    _getBlendState(mode) {
      switch (mode) {
        case constants.BLEND:
          return {
            color: {
              operation: 'add',
              srcFactor: 'one',
              dstFactor: 'one-minus-src-alpha'
            },
            alpha: {
              operation: 'add',
              srcFactor: 'one',
              dstFactor: 'one-minus-src-alpha'
            }
          };

        case constants.ADD:
          return {
            color: {
              operation: 'add',
              srcFactor: 'one',
              dstFactor: 'one'
            },
            alpha: {
              operation: 'add',
              srcFactor: 'one',
              dstFactor: 'one'
            }
          };

        case constants.REMOVE:
          return {
            color: {
              operation: 'add',
              srcFactor: 'zero',
              dstFactor: 'one-minus-src-alpha'
            },
            alpha: {
              operation: 'add',
              srcFactor: 'zero',
              dstFactor: 'one-minus-src-alpha'
            }
          };

        case constants.MULTIPLY:
          return {
            color: {
              operation: 'add',
              srcFactor: 'dst-color',
              dstFactor: 'one-minus-src-alpha'
            },
            alpha: {
              operation: 'add',
              srcFactor: 'dst-alpha',
              dstFactor: 'one-minus-src-alpha'
            }
          };

        case constants.SCREEN:
          return {
            color: {
              operation: 'add',
              srcFactor: 'one',
              dstFactor: 'one-minus-src-color'
            },
            alpha: {
              operation: 'add',
              srcFactor: 'one',
              dstFactor: 'one-minus-src-alpha'
            }
          };

        case constants.EXCLUSION:
          return {
            color: {
              operation: 'add',
              srcFactor: 'one-minus-dst-color',
              dstFactor: 'one-minus-src-color'
            },
            alpha: {
              operation: 'add',
              srcFactor: 'one',
              dstFactor: 'one'
            }
          };

        case constants.REPLACE:
          return {
            color: {
              operation: 'add',
              srcFactor: 'one',
              dstFactor: 'zero'
            },
            alpha: {
              operation: 'add',
              srcFactor: 'one',
              dstFactor: 'zero'
            }
          };

        case constants.SUBTRACT:
          return {
            color: {
              operation: 'reverse-subtract',
              srcFactor: 'one',
              dstFactor: 'one'
            },
            alpha: {
              operation: 'add',
              srcFactor: 'one',
              dstFactor: 'one-minus-src-alpha'
            }
          };

        case constants.DARKEST:
          return {
            color: {
              operation: 'min',
              srcFactor: 'one',
              dstFactor: 'one'
            },
            alpha: {
              operation: 'min',
              srcFactor: 'one',
              dstFactor: 'one'
            }
          };

        case constants.LIGHTEST:
          return {
            color: {
              operation: 'max',
              srcFactor: 'one',
              dstFactor: 'one'
            },
            alpha: {
              operation: 'max',
              srcFactor: 'one',
              dstFactor: 'one'
            }
          };

        default:
          console.warn(`Unsupported blend mode: ${mode}`);
          return undefined;
      }
    }

    _applyColorBlend() {}

    _getVertexLayout(shader) {
      const layouts = [];

      for (const attrName in shader.attributes) {
        const attr = shader.attributes[attrName];
        if (!attr || attr.location === -1) continue;
        // Get the vertex buffer info associated with this attribute
        const renderBuffer =
          this.buffers[shader.shaderType].find(buf => buf.attr === attrName) ||
          this.buffers.user.find(buf => buf.attr === attrName);
        if (!renderBuffer) continue;

        const { size } = renderBuffer;
        // Convert from the number of floats (e.g. 3) to a recognized WebGPU
        // format (e.g. "float32x3")
        const format = this._getFormatFromSize(size);

        layouts.push({
          arrayStride: size * 4,
          stepMode: 'vertex',
          attributes: [
            {
              shaderLocation: attr.location,
              offset: 0,
              format,
            },
          ],
        });
      }
      return layouts;
    }

    _getVertexBuffers(shader) {
      if (!shader._vertexBuffers) {
        const buffers = [];

        for (const attrName in shader.attributes) {
          const attr = shader.attributes[attrName];
          if (!attr || attr.location === -1) continue;

          // Get the vertex buffer info associated with this attribute
          const renderBuffer =
            this.buffers[shader.shaderType].find(buf => buf.attr === attrName) ||
            this.buffers.user.find(buf => buf.attr === attrName);
          if (!renderBuffer) continue;

          buffers.push(renderBuffer);
        }
        shader._vertexBuffers = buffers;
      }

      return shader._vertexBuffers;
    }

    _getFormatFromSize(size) {
      switch (size) {
        case 1: return 'float32';
        case 2: return 'float32x2';
        case 3: return 'float32x3';
        case 4: return 'float32x4';
        default: throw new Error(`Unsupported attribute size: ${size}`);
      }
    }

    _useShader(shader, options) {}

    _updateViewport() {
      this._origViewport = {
        width: this.width,
        height: this.height,
      };
      this._viewport = [0, 0, this.width, this.height];
    }

    _createPixelsArray() {
      this.pixels = new Uint8Array(
        this.width * this.pixelDensity() * this.height * this.pixelDensity() * 4
      );
    }

    supportsTriangleFan() {
      return false;
    }

    viewport() {}

    zClipRange() {
      return [0, 1];
    }
    defaultNearScale() {
      return 0.01;
    }
    defaultFarScale() {
      return 100;
    }

    _resetBuffersBeforeDraw() {
      this._finishActiveRenderPass();

      // Set state to PENDING - we'll decide on first draw
      if (this._pInst.frameCount > 0) {
        this._frameState = FRAME_STATE.PENDING;
      }

      // Clear depth buffer but DON'T start any render pass yet
      const activeFramebuffer = this.activeFramebuffer();
      const commandEncoder = this.device.createCommandEncoder();

      const depthTextureView = activeFramebuffer
        ? (activeFramebuffer.aaDepthTexture
            ? activeFramebuffer.aaDepthTextureView
            : activeFramebuffer.depthTextureView)
        : this.depthTextureView;

      if (depthTextureView) {
        const depthAttachment = {
          view: depthTextureView,
          depthClearValue: 1.0,
          depthLoadOp: 'clear',
          depthStoreOp: 'store',
          stencilLoadOp: 'load',
          stencilStoreOp: 'store',
        };
        const renderPassDescriptor = {
          colorAttachments: [],
          depthStencilAttachment: depthAttachment,
        };
        const passEncoder = commandEncoder.beginRenderPass(renderPassDescriptor);
        passEncoder.end();
        this._pendingCommandEncoders.push(commandEncoder.finish());
        this._hasPendingDraws = true;
      }
    }

    /**
     * Promotes the current frame to use mainFramebuffer.
     * Copies current canvas content to mainFramebuffer, then switches to rendering there.
     * @private
     */
    _promoteToFramebuffer() {
      // Already promoted this frame
      if (this._frameState === FRAME_STATE.PROMOTED) {
        return;
      }

      // Already drawing to a custom framebuffer, no promotion needed
      if (this.activeFramebuffer()) {
        return;
      }

      // Flush any pending draws to canvas first
      this.flushDraw();

      // Mark as promoted
      this._frameState = FRAME_STATE.PROMOTED;

      // Get current canvas texture
      const canvasTexture = this.drawingContext.getCurrentTexture();

      // Ensure mainFramebuffer matches canvas size
      if (this.mainFramebuffer.width !== this.width ||
          this.mainFramebuffer.height !== this.height) {
        this.mainFramebuffer.resize(this.width, this.height);
      }

      // Copy canvas textures to mainFramebuffer
      const commandEncoder = this.device.createCommandEncoder();

      // Copy color texture
      commandEncoder.copyTextureToTexture(
        {
          texture: canvasTexture,
          origin: { x: 0, y: 0, z: 0 },
          mipLevel: 0,
        },
        {
          texture: this.mainFramebuffer.colorTexture,
          origin: { x: 0, y: 0, z: 0 },
          mipLevel: 0,
        },
        {
          width: Math.ceil(this.width * this._pixelDensity),
          height: Math.ceil(this.height * this._pixelDensity),
          depthOrArrayLayers: 1,
        }
      );

      // Copy depth texture
      commandEncoder.copyTextureToTexture(
        {
          texture: this.depthTexture,
          origin: { x: 0, y: 0, z: 0 },
          mipLevel: 0,
        },
        {
          texture: this.mainFramebuffer.depthTexture,
          origin: { x: 0, y: 0, z: 0 },
          mipLevel: 0,
        },
        {
          width: Math.ceil(this.width * this._pixelDensity),
          height: Math.ceil(this.height * this._pixelDensity),
          depthOrArrayLayers: 1,
        }
      );

      this._pendingCommandEncoders.push(commandEncoder.finish());
      this._hasPendingDraws = true;

      // We want to make sure the transformation state is the same
      // once we're drawing to the framebuffer, because normally
      // those are reset.
      const savedModelMatrix = this.states.uModelMatrix.copy();
      this.states.uModelMatrix.set(this.states.uModelMatrix.copy());
      this.states.uModelMatrix.reset();
      this.mainFramebuffer.defaultCamera.set(this.states.curCamera);

      this.mainFramebuffer.begin();

      this.states.uModelMatrix.set(savedModelMatrix);
    }

    _promoteToFramebufferWithoutCopy() {
      // Already promoted this frame
      if (this._frameState === FRAME_STATE.PROMOTED) {
        return;
      }

      // Ensure mainFramebuffer matches canvas size
      if (this.mainFramebuffer.width !== this.width ||
          this.mainFramebuffer.height !== this.height) {
        this.mainFramebuffer.resize(this.width, this.height);
      }

      // Mark as promoted WITHOUT copying canvas content
      this._frameState = FRAME_STATE.PROMOTED;

      // Flush any pending draws first
      this.flushDraw();

      // Preserve transformation state
      const savedModelMatrix = this.states.uModelMatrix.copy();
      this.states.uModelMatrix.set(this.states.uModelMatrix.copy());
      this.states.uModelMatrix.reset();
      this.mainFramebuffer.defaultCamera.set(this.states.curCamera);

      // Begin rendering to mainFramebuffer
      this.mainFramebuffer.begin();

      this.states.uModelMatrix.set(savedModelMatrix);
    }

    //////////////////////////////////////////////
    // Geometry buffer pool management
    //////////////////////////////////////////////

    _initializeGeometryBufferPools(geometry) {
      if (geometry._vertexBufferPools) {
        return; // Already initialized
      }

      geometry._vertexBufferPools = {}; // Keyed by buffer type (dst)
      geometry._vertexBuffersInUse = {}; // Keyed by buffer type (dst)
      geometry._vertexBuffersToReturn = {}; // Keyed by buffer type (dst)

      // Register this geometry for pool cleanup
      this._geometriesWithPools.push(geometry);
    }

    _getVertexBufferFromPool(geometry, dst, size) {
      // Initialize pools if needed
      this._initializeGeometryBufferPools(geometry);

      // Get or create pool for this buffer type
      if (!geometry._vertexBufferPools[dst]) {
        geometry._vertexBufferPools[dst] = [];
      }
      if (!geometry._vertexBuffersInUse[dst]) {
        geometry._vertexBuffersInUse[dst] = [];
      }
      if (!geometry._vertexBuffersToReturn[dst]) {
        geometry._vertexBuffersToReturn[dst] = [];
      }

      // Try to get a buffer from the pool
      const pool = geometry._vertexBufferPools[dst];
      if (pool.length > 0) {
        const bufferInfo = pool.pop();
        // Check if buffer is large enough
        if (bufferInfo.buffer.size >= size) {
          geometry._vertexBuffersInUse[dst].push(bufferInfo);
          return bufferInfo;
        } else {
          // Buffer too small, don't destroy immediately as it may still be in use
          // Add to retirement array
          this._retiredBuffers.push(bufferInfo.buffer);
        }
      }

      // No suitable buffer available, create a new one
      const newBuffer = this.device.createBuffer({
        size,
        usage: GPUBufferUsage.VERTEX | GPUBufferUsage.COPY_DST,
      });

      const bufferInfo = {
        buffer: newBuffer,
        size,
        // Create a copy of the data array to avoid conflicts when geometry is reset
        dataCopy: null
      };

      geometry._vertexBuffersInUse[dst].push(bufferInfo);
      return bufferInfo;
    }

    _returnVertexBuffersToPool() {
      // Return buffers marked for return back to their pools for all registered geometries
      for (const geometry of this._geometriesWithPools) {
        if (geometry._vertexBuffersToReturn) {
          for (const [dst, buffersToReturn] of Object.entries(geometry._vertexBuffersToReturn)) {
            if (buffersToReturn.length > 0) {
              // Move all buffers from ToReturn back to pool
              const pool = geometry._vertexBufferPools[dst] || [];
              while (buffersToReturn.length > 0) {
                const bufferInfo = buffersToReturn.pop();
                // Clear the data copy reference to prevent memory leaks
                bufferInfo.dataCopy = null;
                pool.push(bufferInfo);
              }
              geometry._vertexBufferPools[dst] = pool;
            }
          }
        }
      }
    }

    // Called when geometry is reset - mark its buffers for return
    onReset(geometry) {
      this._markGeometryBuffersForReturn(geometry);
    }

    // Mark geometry buffers for return when geometry is reset/freed
    _markGeometryBuffersForReturn(geometry) {
      if (geometry._vertexBuffersInUse && geometry._vertexBuffersToReturn) {
        for (const [dst, buffersInUse] of Object.entries(geometry._vertexBuffersInUse)) {
          if (buffersInUse.length > 0) {
            // Move all buffers from InUse to ToReturn
            const buffersToReturn = geometry._vertexBuffersToReturn[dst] || [];
            while (buffersInUse.length > 0) {
              const bufferInfo = buffersInUse.pop();
              buffersToReturn.push(bufferInfo);
            }
            geometry._vertexBuffersToReturn[dst] = buffersToReturn;
          }
        }
      }
    }

    //////////////////////////////////////////////
    // Uniform buffer pool management
    //////////////////////////////////////////////

    _getUniformBufferFromPool(bufferGroup) {
      // Try to get a buffer from the pool
      if (bufferGroup.bufferPool.length > 0) {
        const bufferInfo = bufferGroup.bufferPool.pop();
        bufferGroup.buffersInUse.add(bufferInfo);
        return bufferInfo;
      }

      // No buffers available, create a new one
      const newBuffer = this.device.createBuffer({
        size: bufferGroup.size,
        usage: GPUBufferUsage.UNIFORM | GPUBufferUsage.COPY_DST,
      });
      const newData = new Float32Array(bufferGroup.size / 4);
      const newDataView = new DataView(newData.buffer);
      const bufferInfo = {
        buffer: newBuffer,
        data: newData,
        dataView: newDataView
      };

      bufferGroup.buffersInUse.add(bufferInfo);
      return bufferInfo;
    }

    _getDynamicUniformBufferFromPool(bufferGroup) {
      //
      let buffer;
      if (
        this.currentUniformBuffer &&
        this.currentUniformBuffer.offset + bufferGroup.size < this.currentUniformBuffer.size
      ) {
        // We can fit this next block of uniforms into the current active memory chunk
        buffer = this.currentUniformBuffer;
      } else if (this.uniformBufferPool.length > 0) {
        buffer = this.uniformBufferPool.pop();
        this.activeUniformBuffers.push(buffer);
      } else {
        // Kinda arbitrary. Each dynamic offset has to be in groups of 256, but then
        // we can choose how many things we want to be able to fit into a block.
        // There's some overhead to each block so if we're drawing a lot of stuff,
        // bigger is better. But it's also a lot of wasted memory if we AREN'T drawing
        // a lot of stuff. So.... right now it's 40. Feel free to update this if
        // a better balance can be achieved.
        const size = 256 * 40;
        buffer = {
          dynamic: true,
          lastOffset: 0,
          offset: 0,
          size,
          buffer: this.device.createBuffer({
            size,
            usage: GPUBufferUsage.MAP_WRITE | GPUBufferUsage.COPY_SRC,
            mappedAtCreation: true,
          }),
          uniformBuffer: this.device.createBuffer({
            size,
            usage: GPUBufferUsage.UNIFORM | GPUBufferUsage.COPY_DST,
          }),
        }

        buffer.data = new Float32Array(buffer.buffer.getMappedRange());
        buffer.dataView = new DataView(buffer.data.buffer);

        this.activeUniformBuffers.push(buffer);
      }

      this.currentUniformBuffer = buffer;

      return buffer;
    }

    _returnUniformBuffersToPool() {
      // Return all used buffers back to their pools for all registered shaders
      for (const shader of this._shadersWithPools) {
        this._returnShaderBuffersToPool(shader);
      }
    }

    _returnShaderBuffersToPool(shader) {
      if (shader._uniformBufferGroups) {
        for (const bufferGroup of shader._uniformBufferGroups) {
          while (bufferGroup.nextBufferPool.length > 0) {
            bufferGroup.bufferPool.push(bufferGroup.nextBufferPool.pop());
          }
          for (const bufferInfo of bufferGroup.buffersInUse.keys()) {
            if (bufferInfo !== bufferGroup.currentBuffer) {
              bufferGroup.nextBufferPool.push(bufferInfo);
            }
          }
          bufferGroup.buffersInUse.clear();
          if (bufferGroup.currentBuffer) {
            bufferGroup.buffersInUse.add(bufferGroup.currentBuffer);
          }
        }
      }
    }

    flushDraw() {
      this._finishActiveRenderPass();
      // Only submit if we actually had any draws
      if (this._hasPendingDraws) {
        // Create a copy of pending command encoders
        const commandsToSubmit = this._pendingCommandEncoders;
        this._pendingCommandEncoders = [];
        this._hasPendingDraws = false;

        if (this.activeUniformBuffers.length > 0) {
          const encoder = this.device.createCommandEncoder();
          for (const bufferInfo of this.activeUniformBuffers) {
            bufferInfo.buffer.unmap();
            encoder.copyBufferToBuffer(
              bufferInfo.buffer,
              bufferInfo.uniformBuffer,
            );
          }
          commandsToSubmit.unshift(encoder.finish());
        }

        // Submit the commands
        this.queue.submit(commandsToSubmit);

        for (const buf of this.activeUniformBuffers) {
          // buf.buffer = this.device.createBuffer({
            // size: buf.size,
            // usage: GPUBufferUsage.MAP_WRITE | GPUBufferUsage.COPY_SRC,
            // mappedAtCreation: true,
          // });
          buf.offset = 0;
          buf.lastOffset = 0;
          // this.resettingUniformBuffers.push(
            buf.buffer.mapAsync(GPUMapMode.WRITE).then(() => {
              buf.data = new Float32Array(buf.buffer.getMappedRange());
              buf.dataView = new DataView(buf.data.buffer);
              this.uniformBufferPool.push(buf);
              return buf;
            })
          // )
        }
        this.activeUniformBuffers = [];
        this.currentUniformBuffer = undefined;

        // Execute post-submit callbacks after GPU work completes
        if (this._postSubmitCallbacks.length > 0) {
          const callbacks = this._postSubmitCallbacks;
          this._postSubmitCallbacks = [];
          this.device.queue.onSubmittedWorkDone().then(() => {
            for (const callback of callbacks) {
              callback();
            }
          });
        }

        // Reset canvas texture cache for next frame
        this.currentCanvasColorTexture = null;
        this.currentCanvasColorTextureView = null;
      }
    }

    _ensurePixelReadCanvas(width, height) {
      // Create canvas if it doesn't exist
      if (!this._pixelReadCanvas) {
        this._pixelReadCanvas = document.createElement('canvas');
        this._pixelReadCtx = this._pixelReadCanvas.getContext('2d');
      }

      // Resize canvas if dimensions changed
      if (this._pixelReadCanvas.width !== width || this._pixelReadCanvas.height !== height) {
        this._pixelReadCanvas.width = width;
        this._pixelReadCanvas.height = height;
      }

      return { canvas: this._pixelReadCanvas, ctx: this._pixelReadCtx };
    }

    resize(w, h) {
      super.resize(w, h);
      this._hasPendingDraws = true;
      this.flushDraw();
    }

    async finishDraw() {
      this.flushDraw();

      const states = [];

      // Only blit if we promoted to framebuffer this frame
      if (this._frameState === FRAME_STATE.PROMOTED) {
        while (this.activeFramebuffers.length > 0) {
          const fbo = this.activeFramebuffers.pop();
          states.unshift({ fbo, diff: { ...this.states } });
        }
        this.flushDraw();

        this._pInst.push();
        this.states.setValue('enableLighting', false);
        this.states.setValue('activeImageLight', null);
        this._pInst.setCamera(this.finalCamera);
        this._pInst.shader(this._getBlitShader());
        this._pInst.resetMatrix();
        this._pInst.imageMode(this._pInst.CENTER);
        this._pInst.image(this.mainFramebuffer, 0, 0);
        this._pInst.pop();
        this.flushDraw();
      }

      // Return all uniform buffers to their pools
      this._returnUniformBuffersToPool();

      // Mark all geometry buffers for return after frame is complete
      for (const geometry of this._geometriesWithPools) {
        this._markGeometryBuffersForReturn(geometry);
      }

      // this.uniformBufferPool.push(...(await Promise.all(this.resettingUniformBuffers)));
      this.resettingUniformBuffers = [];

      // Return all vertex buffers to their pools
      this._returnVertexBuffersToPool();

      // Destroy all retired buffers
      const retired = this._retiredBuffers;
      this._postSubmitCallbacks.push(() => {
        for (const buffer of retired) {
          if (buffer && buffer.destroy) {
            buffer.destroy();
          }
        }
      });
      this._retiredBuffers = [];

      if (this._frameState === FRAME_STATE.PROMOTED) {
        for (const { fbo, diff } of states) {
          if (fbo !== this.mainFramebuffer || this._frameState !== FRAME_STATE.PROMOTED) {
            fbo.begin();
          }
          for (const key in diff) {
            this.states.setValue(key, diff[key]);
          }
        }
      }
    }

    //////////////////////////////////////////////
    // Rendering
    //////////////////////////////////////////////

    _drawBuffers(geometry, { mode = constants.TRIANGLES, count = 1 }) {
      const buffers = this.geometryBufferCache.getCached(geometry);
      if (!buffers) return;

      // If PENDING and no custom framebuffer, regular draw means PROMOTE
      if (this._frameState === FRAME_STATE.PENDING && !this.activeFramebuffer()) {
        this._promoteToFramebufferWithoutCopy();
      }

      this._beginActiveRenderPass();
      const passEncoder = this.activeRenderPass;

      const currentShader = this._curShader;
      this.setupShaderBindGroups(currentShader, passEncoder, { mode, buffers });
      // Bind vertex buffers
      for (const buffer of currentShader._vertexBuffers || this._getVertexBuffers(currentShader)) {
        const location = currentShader.attributes[buffer.attr].location;
        const gpuBuffer = buffers[buffer.dst];
        passEncoder.setVertexBuffer(location, gpuBuffer, 0);
      }

      if (currentShader.shaderType === "fill") {
        // Bind index buffer and issue draw
        if (buffers.indexBuffer) {
          const indexFormat = buffers.indexFormat || "uint16";
          passEncoder.setIndexBuffer(buffers.indexBuffer, indexFormat);
          passEncoder.drawIndexed(geometry.faces.length * 3, count, 0, 0, 0);
        } else {
          passEncoder.draw(geometry.vertices.length, count, 0, 0);
        }
      } else if (currentShader.shaderType === "text") {
        if (!buffers.indexBuffer) {
          throw new Error("Text geometry must have an index buffer");
        }
        const indexFormat = buffers.indexFormat || "uint16";
        passEncoder.setIndexBuffer(buffers.indexBuffer, indexFormat);
        passEncoder.drawIndexed(geometry.faces.length * 3, count, 0, 0, 0);
      }

      if (buffers.lineVerticesBuffer && currentShader.shaderType === "stroke") {
        passEncoder.draw(geometry.lineVertices.length / 3, count, 0, 0);
      }

      // Mark that we have pending draws that need submission
      this._hasPendingDraws = true;
    }

    setupShaderBindGroups(currentShader, passEncoder, shaderOptionsParams) {
      const shaderOptions = this._shaderOptions(shaderOptionsParams);
      if (
        shaderOptions.compute ||
        this.activeShader !== currentShader ||
        this._shaderOptionsDifferent(shaderOptions)
      ) {
        passEncoder.setPipeline(currentShader.getPipeline(shaderOptions));
      }
      if (!shaderOptions.compute) {
        this.activeShader = currentShader;
        this.activeShaderOptions = shaderOptions;

        // Set stencil reference value for clipping
        const drawTarget = this.drawTarget();
        if (drawTarget._isClipApplied && !this._clipping) {
          // When using the clip mask, test against reference value 0 (background)
          // WebGL uses NOTEQUAL with ref 0, so fragments pass where stencil != 0
          // In WebGPU with 'not-equal', we need ref 0 to pass where stencil != 0
          passEncoder.setStencilReference(0);
        } else if (this._clipping) {
          // When writing to the clip mask, write reference value 1
          passEncoder.setStencilReference(1);
        }
      }

      for (const bufferGroup of currentShader._uniformBufferGroups) {
        if (bufferGroup.dynamic) {
          // Bind uniforms into a part of a big dynamic memory block because
          // the group changes often
          const uniformBufferInfo = this._getDynamicUniformBufferFromPool(bufferGroup);
          if (currentShader._lastDynamicBuffer[bufferGroup.cacheKey] !== uniformBufferInfo) {
            currentShader._cachedBindGroup[bufferGroup.group] = undefined;
            currentShader._lastDynamicBuffer[bufferGroup.cacheKey] = uniformBufferInfo;
          }
          this._packUniformGroup(currentShader, bufferGroup.uniforms, uniformBufferInfo);
          uniformBufferInfo.lastOffset = uniformBufferInfo.offset;
          uniformBufferInfo.offset += Math.ceil(bufferGroup.size / this.uniformBufferAlignment) * this.uniformBufferAlignment;

          // Make a shallow copy so that we keep track of the last offset for this uniform
          bufferGroup.currentDynamicBuffer = uniformBufferInfo;
          bufferGroup.lastOffset = uniformBufferInfo.lastOffset;
        } else {
          // Bind uniforms to a binding-specific buffer, which may be cached for performance
          let bufferInfo;
          const dataChanged = this._hasGroupDataChanged(currentShader, bufferGroup);

          if (!dataChanged && bufferGroup.currentBuffer) {
            // Reuse the cached buffer - no need to pack or write
            bufferInfo = bufferGroup.currentBuffer;
            bufferGroup.buffersInUse.add(bufferInfo);
          } else {
            // Data changed - get a new buffer and write to it
            bufferInfo = this._getUniformBufferFromPool(bufferGroup);
            this._packUniformGroup(currentShader, bufferGroup.uniforms, bufferInfo);
            this.device.queue.writeBuffer(
              bufferInfo.buffer,
              0,
              bufferInfo.data.buffer,
              bufferInfo.data.byteOffset,
              bufferInfo.data.byteLength
            );

            currentShader.buffersDirty.delete(bufferGroup.group * 1000 + bufferGroup.binding);
            currentShader._cachedBindGroup[bufferGroup.group] = undefined;

            // Cache this buffer and data for next frame
            bufferGroup.currentBuffer = bufferInfo;
          }
        }
      }
      for (const sampler of currentShader.samplers) {
        const key = sampler.group * 1000 + sampler.binding;
        if (currentShader.buffersDirty.has(key)) {
          currentShader._cachedBindGroup[sampler.group] = undefined;
          currentShader.buffersDirty.delete(key);
        }
      }
      for (const storage of currentShader._storageBuffers || []) {
        const key = storage.group * 1000 + storage.binding;
        if (currentShader.buffersDirty.has(key)) {
          currentShader._cachedBindGroup[storage.group] = undefined;
          currentShader.buffersDirty.delete(key);
        }
      }

      // Bind sampler/texture uniforms and uniform buffers
      for (const iter of currentShader._groupEntries) {
        const group = iter[0];
        const entries = iter[1];
        let dynamicOffsetIdx = 0;
        const bgEntries = [];
        let bindGroup = currentShader._cachedBindGroup[group];
        for (const entry of entries) {
          const bufferGroup = entry.bufferGroup;
          // Check if this is a uniform buffer binding
          const uniformBufferInfo =
            bufferGroup?.currentBuffer || bufferGroup?.currentDynamicBuffer;
          if (uniformBufferInfo) {
            if (bufferGroup.dynamic) {
              this.dynamicEntryOffsets[dynamicOffsetIdx++] = bufferGroup.lastOffset;
            }
            if (!bindGroup) {
              bgEntries.push({
                binding: entry.binding,
                resource: bufferGroup.dynamic
                  ? {
                    buffer: uniformBufferInfo.uniformBuffer,
                    offset: 0,
                    size: Math.ceil(bufferGroup.size / this.uniformBufferAlignment) * this.uniformBufferAlignment,
                  }
                  : { buffer: uniformBufferInfo.buffer },
              });
            }
          } else if (entry.storage && !bindGroup) {
            // Storage buffer binding
            const uniform = currentShader.uniforms[entry.storage.name];
            if (!uniform || !uniform._cachedData || !uniform._cachedData._isStorageBuffer) {
              throw new Error(
                `Storage buffer "${entry.storage.name}" not set. ` +
                `Use shader.setUniform("${entry.storage.name}", storageBuffer)`
              );
            }
            bgEntries.push({
              binding: entry.binding,
              resource: { buffer: uniform._cachedData.buffer },
            });
          } else if (!bindGroup) {
            bgEntries.push({
              binding: entry.binding,
              resource: entry.uniform.type === 'sampler'
                ? (entry.uniform.textureSource.texture || this._getEmptyTexture()).getSampler()
                : (entry.uniform.texture || this._getEmptyTexture()).textureHandle.view,
            });
          }
        }

        const layout = currentShader._bindGroupLayouts[group];
        if (!bindGroup) {
          bindGroup = this.device.createBindGroup({
            layout,
            entries: bgEntries,
          });
        }
        currentShader._cachedBindGroup[group] = bindGroup;
        if (dynamicOffsetIdx === 0) {
          passEncoder.setBindGroup(
            group,
            bindGroup,
          );
        } else {
          passEncoder.setBindGroup(
            group,
            bindGroup,
            this.dynamicEntryOffsets,
            0,
            dynamicOffsetIdx
          );
        }
      }
      return passEncoder;
    }

    //////////////////////////////////////////////
    // SHADER
    //////////////////////////////////////////////

    // Writes a single field's value into a Float32Array+DataView at (baseOffset + field.offset).
    //
    // Field interface (shared by uniform fields from _parseStruct and struct storage schema fields):
    //   baseType:    string  - 'f32', 'i32', 'u32', etc.
    //   size:        number  - byte size of the field
    //   offset:      number  - byte offset of the field within its struct
    //   packInPlace: bool    - true for mat3, written with manual column padding
    //
    // value: number or number[] - the data to write
    _packField(field, value, floatView, dataView, baseOffset) {
      if (value === undefined) return;

      // Duck typing instead of instanceof to avoid importing a separate
      // copy of the Color/Vector classes
      if (value?.isVector) {
        value = value.values.length !== value.dimensions ? value.values.slice(0, value.dimensions) : value.values;
      } else if (value?.isColor) {
        value = value._getRGBA([1, 1, 1, 1]);
      }
      const byteOffset = baseOffset + field.offset;
      if (field.baseType === 'u32') {
        if (field.size === 4) {
          dataView.setUint32(byteOffset, value, true);
        } else {
          for (let i = 0; i < value.length; i++) {
            dataView.setUint32(byteOffset + i * 4, value[i], true);
          }
        }
      } else if (field.baseType === 'i32') {
        if (field.size === 4) {
          dataView.setInt32(byteOffset, value, true);
        } else {
          for (let i = 0; i < value.length; i++) {
            dataView.setInt32(byteOffset + i * 4, value[i], true);
          }
        }
      } else if (field.packInPlace) {
        // In-place packing for mat3: write directly to buffer with padding
        const base = byteOffset / 4;
        floatView[base + 0] = value[0]; floatView[base + 1] = value[1]; floatView[base + 2] = value[2];
        floatView[base + 4] = value[3]; floatView[base + 5] = value[4]; floatView[base + 6] = value[5];
        floatView[base + 8] = value[6]; floatView[base + 9] = value[7]; floatView[base + 10] = value[8];
      } else if (field.size === 4) {
        floatView.set([value], byteOffset / 4);
      } else {
        floatView.set(value, byteOffset / 4);
      }
    }

    _packUniformGroup(shader, groupUniforms, bufferInfo) {
      // Pack a single group's uniforms into a buffer
      const data = bufferInfo.data;
      const dataView = bufferInfo.dataView;
      const offset = bufferInfo.offset || 0;
      for (const uniform of groupUniforms) {
        const fullUniform = shader.uniforms[uniform.name];
        if (!fullUniform || fullUniform.isSampler) continue;
        this._packField(fullUniform, fullUniform._mappedData, data, dataView, offset);
      }
    }

    _hasGroupDataChanged(shader, bufferGroup) {
      // First time
      if (!bufferGroup.currentBuffer) return true;
      return shader.buffersDirty.has(bufferGroup.group * 1000 + bufferGroup.binding);
    }

    _parseStruct(shaderSource, structName) {
      const structMatch = shaderSource.match(
        new RegExp(`struct\\s+${structName}\\s*\\{([^\\}]+)\\}`)
      );
      if (!structMatch) {
        throw new Error(`Can't find a struct definition for ${structName}`);
      }

      const structBody = structMatch[1];
      const elements = {};
      let match;
      let index = 0;
      let offset = 0;

      const elementRegex =
        /(?:@location\((\d+)\)\s+)?(\w+):\s*([^\n]+?),?\n/g

      const baseAlignAndSize = (type) => {
        if (['f32', 'i32', 'u32', 'bool'].includes(type)) {
          return { align: 4, size: 4, items: 1, baseType: type };
        }
        if (/^vec[2-4](<f32>|f)$/.test(type)) {
          const n = parseInt(type.match(/^vec([2-4])/)[1]);
          const size = 4 * n;
          const align = n === 2 ? 8 : 16;
          return { align, size, items: n, baseType: 'f32' };
        }
        if (/^vec[2-4]<(i32|u32)>$/.test(type)) {
          const n = parseInt(type.match(/^vec([2-4])/)[1]);
          const match = type.match(/^vec[2-4]<(i32|u32)>$/);
          const baseType = match[1]; // 'i32' or 'u32'
          const size = 4 * n;
          const align = n === 2 ? 8 : 16;
          return { align, size, items: n, baseType };
        }
        if (/^mat[2-4](?:x[2-4])?(<f32>|f)$/.test(type)) {
          if (type[4] === 'x' && type[3] !== type[5]) {
            throw new Error('Non-square matrices not implemented yet');
          }
          const dim = parseInt(type[3]);
          const align = dim === 2 ? 8 : 16;
          // Each column must be aligned
          const size = Math.ceil(dim * 4 / align) * align * dim;
          // For mat3, use in-place packing to avoid array allocation
          const pack = dim === 3
            ? (data) => [
              ...data.slice(0, 3),
              ...data.slice(3, 6),
              ...data.slice(6, 9),
            ]
            : undefined;
          const packInPlace = dim === 3;
          return { align, size, pack, packInPlace, items: dim * dim, baseType: 'f32' };
        }
        if (/^array<.+>$/.test(type)) {
          const [, subtype, rawLength] = type.match(/^array<(.+),\s*(\d+)>/);
          const length = parseInt(rawLength);
          const {
            align: elemAlign,
            size: elemSize,
            items: elemItems,
            pack: elemPack = (data) => [...data],
            baseType: elemBaseType
          } = baseAlignAndSize(subtype);
          const stride = Math.ceil(elemSize / elemAlign) * elemAlign;
          const pack = (data) => {
            const result = [];
            for (let i = 0; i < data.length; i += elemItems) {
              const elemData = elemPack(data.slice(i, elemItems))
              result.push(...elemData);
              for (let j = 0; j < stride / 4 - elemData.length; j++) {
                result.push(0);
              }
            }
            return result;
          };
          return {
            align: elemAlign,
            size: stride * length,
            items: elemItems * length,
            pack,
            baseType: elemBaseType
          };
        }
        throw new Error(`Unknown type in WGSL struct: ${type}`);
      };

      while ((match = elementRegex.exec(structBody)) !== null) {
        const [_, location, name, type] = match;
        const { size, align, pack, packInPlace, baseType } = baseAlignAndSize(type);
        offset = Math.ceil(offset / align) * align;
        const offsetEnd = offset + size;
        elements[name] = {
          name,
          location: location ? parseInt(location) : undefined,
          index,
          type,
          size,
          offset,
          offsetEnd,
          pack,
          packInPlace,
          baseType
        };
        index++;
        offset = offsetEnd;
      }

      return elements;
    }

    _mapUniformData(uniform, data) {
      if (uniform.pack) {
        return uniform.pack(data);
      }
      return data;
    }

    _getShaderAttributes(shader) {
      const mainMatch = /fn main\(.+:\s*([^\s\)]+)/.exec(shader._vertSrc);
      if (!mainMatch) throw new Error("Can't find `fn main` in vertex shader source");
      const inputType = mainMatch[1];

      return this._parseStruct(shader.vertSrc(), inputType);
    }

    getUniformMetadata(shader) {
      // Parse all uniform struct bindings in group 0.
      // TODO: support non-sampler uniforms being in other groups

      // Each binding represents a logical group of uniforms, since they get
      // updated or cached all at once.

      const uniformGroups = [];
      const uniformVarRegex = /@group\((\d+)\)\s+@binding\((\d+)\)\s+var<uniform>\s+(\w+)\s*:\s*(\w+);/g;

      let match;
      const src = shader.shaderType === 'compute' ? shader.computeSrc() : shader.vertSrc();
      while ((match = uniformVarRegex.exec(src)) !== null) {
        const [_, groupNum, binding, varName, structType] = match;
        const bindingIndex = parseInt(binding);
        const uniforms = this._parseStruct(src, structType);

        uniformGroups.push({
          group: parseInt(groupNum),
          binding: bindingIndex,
          varName,
          structType,
          uniforms
        });
      }

      if (uniformGroups.length === 0 && shader.shaderType !== 'compute') {
        throw new Error('Expected at least one uniform struct bound to @group(0)');
      }

      // While we're also keeping track of the groups, the API we expose
      // to users of p5 is just a flat list of uniforms (which can be the
      // individual struct items in the group.)
      const allUniforms = {};
      for (const group of uniformGroups) {
        for (const [uniformName, uniformData] of Object.entries(group.uniforms)) {
          allUniforms[uniformName] = {
            ...uniformData,
            group: group.group,
            binding: group.binding,
            varName: group.varName
          };
        }
      }

      // Store uniform groups for buffer pooling
      shader._uniformGroups = uniformGroups;

      // Extract samplers from group bindings
      const samplers = {};
      // TODO: support other texture types
      const samplerRegex = /@group\((\d+)\)\s*@binding\((\d+)\)\s*var\s+(\w+)\s*:\s*(texture_2d<f32>|sampler);/g;

      // Extract storage buffers
      const storageBuffers = {};
      const storageRegex = /@group\((\d+)\)\s*@binding\((\d+)\)\s*var<storage,\s*(read|read_write)>\s+(\w+)\s*:\s*array<\w+>/g;

      // Track which bindings are taken by the struct properties we've parsed
      // (the rest should be textures/samplers)
      const structUniformBindings = {};
      for (const g of uniformGroups) {
        structUniformBindings[g.group + ',' + g.binding] = true;
      }

      for (const [src, visibility] of [
        [shader.vertSrc(), GPUShaderStage.VERTEX],
        [shader.fragSrc(), GPUShaderStage.FRAGMENT],
        [shader.computeSrc ? shader.computeSrc() : null, GPUShaderStage.COMPUTE]
      ]) {
        if (!src) continue; // Skip if shader stage doesn't exist

        let match;
        while ((match = samplerRegex.exec(src)) !== null) {
          const [_, group, binding, name, type] = match;
          const groupIndex = parseInt(group);
          const bindingIndex = parseInt(binding);
          // Skip struct uniform bindings which we've already parsed
          if (structUniformBindings[groupIndex + ',' + bindingIndex]) continue;

          const key = `${groupIndex},${bindingIndex}`;
          samplers[key] = {
            visibility: (samplers[key]?.visibility || 0) | visibility,
            group: groupIndex,
            binding: bindingIndex,
            name,
            type,
            isSampler: true,
            noData: type === 'sampler',
          };
        }

        for (const sampler of Object.values(samplers)) {
          if (sampler.type.startsWith('texture')) {
            const samplerName = sampler.name + '_sampler';
            const samplerNode = Object
              .values(samplers)
              .find((s) => s.name === samplerName);
            if (!samplerNode) {
              throw new Error(
                `Every shader texture needs an accompanying sampler. Could not find sampler ${samplerName} for texture ${sampler.name}`
              );
            }
            samplerNode.textureSource = sampler;
          }
        }

        // Parse storage buffers
        while ((match = storageRegex.exec(src)) !== null) {
          const [_, group, binding, accessMode, name] = match;
          const groupIndex = parseInt(group);
          const bindingIndex = parseInt(binding);

          const key = `${groupIndex},${bindingIndex}`;
          const existing = storageBuffers[key];
          // If any stage uses read_write, the bind group layout must use read_write
          const finalAccessMode = (existing?.accessMode === 'read_write' || accessMode === 'read_write')
            ? 'read_write'
            : accessMode;

          storageBuffers[key] = {
            visibility: (existing?.visibility || 0) | visibility,
            group: groupIndex,
            binding: bindingIndex,
            name,
            accessMode: finalAccessMode, // 'read' or 'read_write'
            isStorage: true,
            type: 'storage'
          };
        }
      }

      // Store storage buffers on shader for later use
      shader._storageBuffers = Object.values(storageBuffers);

      return [...Object.values(allUniforms).sort((a, b) => a.index - b.index), ...Object.values(samplers), ...Object.values(storageBuffers)];
    }

    getNextBindingIndex({ vert, frag, compute }, group = 0) {
      // Get the highest binding index in the specified group and return the next available
      const bindingRegex = /@group\((\d+)\)\s*@binding\((\d+)\)/g;
      let maxBindingIndex = -1;

      const sources = [];
      if (vert) sources.push([vert, GPUShaderStage.VERTEX]);
      if (frag) sources.push([frag, GPUShaderStage.FRAGMENT]);
      if (compute) sources.push([compute, GPUShaderStage.COMPUTE]);

      for (const [src, visibility] of sources) {
        let match;
        while ((match = bindingRegex.exec(src)) !== null) {
          const [_, groupIndex, bindingIndex] = match;
          if (parseInt(groupIndex) === group) {
            maxBindingIndex = Math.max(maxBindingIndex, parseInt(bindingIndex));
          }
        }
      }

      return maxBindingIndex + 1;
    }

    updateUniformValue(shader, uniform, data) {
      if (uniform.isSampler) {
        uniform.texture =
          data instanceof Texture ? data : this.getTexture(data);
      } else if (!data?._isStorageBuffer) {
        uniform._mappedData = this._mapUniformData(uniform, uniform._cachedData);
      }
      shader.buffersDirty.add(uniform.group * 1000 + uniform.binding);
    }

    _updateTexture(uniform, tex) {
      tex.update();
    }

    bindTexture(tex) {}
    unbindTexture(tex) {}
    _unbindFramebufferTexture(uniform) {}

    createTexture({ width, height, format = 'rgba8unorm', usage }) {
      const gpuTexture = this.device.createTexture({
        size: [width, height],
        format,
        usage: usage || (
          GPUTextureUsage.TEXTURE_BINDING |
          GPUTextureUsage.COPY_DST |
          GPUTextureUsage.RENDER_ATTACHMENT
        ),
      });
      return { gpuTexture, view: gpuTexture.createView() };
    }

    uploadTextureFromSource({ gpuTexture }, source) {
      this.queue.copyExternalImageToTexture(
        { source },
        { texture: gpuTexture },
        [source.width, source.height]
      );

      // Force submission to ensure texture upload completes before usage
      this._hasPendingDraws = true;
      this.flushDraw();
    }

    uploadTextureFromData({ gpuTexture }, data, width, height) {
      this.queue.writeTexture(
        { texture: gpuTexture },
        data,
        { bytesPerRow: width * 4, rowsPerImage: height },
        { width, height, depthOrArrayLayers: 1 }
      );

      // Force submission to ensure texture upload completes before usage
      this._hasPendingDraws = true;
      this.flushDraw();
    }

    setTextureParams(_texture) {}

    getSampler(texture) {
      const key = `${texture.minFilter}_${texture.magFilter}_${texture.wrapS}_${texture.wrapT}`;
      if (this.samplers.has(key)) {
        return this.samplers.get(key);
      }
      const constantMapping = {
        [constants.NEAREST]: 'nearest',
        [constants.LINEAR]: 'linear',
        [constants.CLAMP]: 'clamp-to-edge',
        [constants.REPEAT]: 'repeat',
        [constants.MIRROR]: 'mirror-repeat'
      }
      const sampler = this.device.createSampler({
        magFilter: constantMapping[texture.magFilter],
        minFilter: constantMapping[texture.minFilter],
        addressModeU: constantMapping[texture.wrapS],
        addressModeV: constantMapping[texture.wrapT],
      });
      this.samplers.set(key, sampler);
      return sampler;
    }

    bindTextureToShader(_texture, _sampler, _uniformName, _unit) {}

    deleteTexture({ gpuTexture }) {
      this._postSubmitCallbacks.push(() => gpuTexture.destroy());
    }

    _getLightShader() {
      if (!this._defaultLightShader) {
        this._defaultLightShader = new Shader(
          this,
          materialVertexShader,
          materialFragmentShader,
          {
            vertex: {
              "void beforeVertex": "() {}",
              "Vertex getObjectInputs": "(inputs: Vertex) { return inputs; }",
              "Vertex getWorldInputs": "(inputs: Vertex) { return inputs; }",
              "Vertex getCameraInputs": "(inputs: Vertex) { return inputs; }",
              "void afterVertex": "() {}",
            },
            fragment: {
              "void beforeFragment": "() {}",
              "Inputs getPixelInputs": "(inputs: Inputs) { return inputs; }",
              "vec4f combineColors": `(components: ColorComponents) {
                var rgb = vec3<f32>(0.0);
                rgb += components.diffuse * components.baseColor;
                rgb += components.ambient * components.ambientColor;
                rgb += components.specular * components.specularColor;
                rgb += components.emissive;
                return vec4<f32>(rgb, components.opacity);
              }`,
              "vec4f getFinalColor": "(color: vec4<f32>, texCoord: vec2<f32>) { return color; }",
              "void afterFragment": "() {}",
            },
          }
        );
      }
      return this._defaultLightShader;
    }

    _getColorShader() {
      if (!this._defaultColorShader) {
        this._defaultColorShader = new Shader(
          this,
          colorVertexShader,
          colorFragmentShader,
          {
            vertex: {
              "void beforeVertex": "() {}",
              "Vertex getObjectInputs": "(inputs: Vertex) { return inputs; }",
              "Vertex getWorldInputs": "(inputs: Vertex) { return inputs; }",
              "Vertex getCameraInputs": "(inputs: Vertex) { return inputs; }",
              "void afterVertex": "() {}",
            },
            fragment: {
              "void beforeFragment": "() {}",
              "vec4<f32> getFinalColor": "(color: vec4<f32>, texCoord: vec2<f32>) { return color; }",
              "void afterFragment": "() {}",
            },
          }
        );
      }
      return this._defaultColorShader;
    }

    _getLineShader() {
      if (!this._defaultLineShader) {
        this._defaultLineShader = new Shader(
          this,
          lineDefs + lineVertexShader,
          lineDefs + lineFragmentShader,
          {
            vertex: {
              "void beforeVertex": "() {}",
              "StrokeVertex getObjectInputs": "(inputs: StrokeVertex) { return inputs; }",
              "StrokeVertex getWorldInputs": "(inputs: StrokeVertex) { return inputs; }",
              "StrokeVertex getCameraInputs": "(inputs: StrokeVertex) { return inputs; }",
              "void afterVertex": "() {}",
            },
            fragment: {
              "void beforeFragment": "() {}",
              "Inputs getPixelInputs": "(inputs: Inputs) { return inputs; }",
              "vec4<f32> getFinalColor": "(color: vec4<f32>, texCoord: vec2<f32>) { return color; }",
              "bool shouldDiscard": "(outside: bool) { return outside; };",
              "void afterFragment": "() {}",
            },
          }
        );
      }
      return this._defaultLineShader;
    }

    _getFontShader() {
      if (!this._defaultFontShader) {
        this._defaultFontShader = new Shader(
          this,
          fontVertexShader,
          fontFragmentShader
        );
      }
      return this._defaultFontShader;
    }

    _getBlitShader() {
      if (!this._defaultBlitShader) {
        this._defaultBlitShader = new Shader(
          this,
          blitVertexShader,
          blitFragmentShader
        );
      }
      return this._defaultBlitShader;
    }

    //////////////////////////////////////////////
    // Setting
    //////////////////////////////////////////////
    _adjustDimensions(width, height) {
      // TODO: find max texture size
      return { adjustedWidth: width, adjustedHeight: height };
    }

    _applyClip() {
      const commandEncoder = this.device.createCommandEncoder();

      const activeFramebuffer = this.activeFramebuffer();
      const depthTextureView = activeFramebuffer
        ? (activeFramebuffer.aaDepthTexture
            ? activeFramebuffer.aaDepthTextureView
            : activeFramebuffer.depthTextureView)
        : this.depthTextureView;

      if (!depthTextureView) {
        return;
      }

      const depthStencilAttachment = {
        view: depthTextureView,
        stencilLoadOp: 'clear',
        stencilStoreOp: 'store',
        stencilClearValue: 0,
        depthReadOnly: true,
        stencilReadOnly: false,
      };

      const renderPassDescriptor = {
        colorAttachments: [],
        depthStencilAttachment: depthStencilAttachment,
      };

      const passEncoder = commandEncoder.beginRenderPass(renderPassDescriptor);
      passEncoder.end();

      this._pendingCommandEncoders.push(commandEncoder.finish());
      this._hasPendingDraws = true;
    }

    _unapplyClip() {
      // In WebGPU, clip unapplication is handled through pipeline state rather than direct commands
      // The stencil test configuration is set in the render pipeline based on _clipping and _clipInvert flags
      // This is already handled in the _shaderOptions() method and pipeline creation
    }

    _clearClipBuffer() {
      this._finishActiveRenderPass();
      const commandEncoder = this.device.createCommandEncoder();

      const activeFramebuffer = this.activeFramebuffer();
      const depthTextureView = activeFramebuffer
        ? (activeFramebuffer.aaDepthTexture
            ? activeFramebuffer.aaDepthTextureView
            : activeFramebuffer.depthTextureView)
        : this.depthTextureView;

      if (!depthTextureView) {
        return;
      }

      const depthStencilAttachment = {
        view: depthTextureView,
        stencilLoadOp: 'clear',
        stencilStoreOp: 'store',
        stencilClearValue: 1,
        depthReadOnly: true,
        stencilReadOnly: false,
      };

      const renderPassDescriptor = {
        colorAttachments: [],
        depthStencilAttachment: depthStencilAttachment,
      };

      const passEncoder = commandEncoder.beginRenderPass(renderPassDescriptor);
      passEncoder.end();

      this._pendingCommandEncoders.push(commandEncoder.finish());
      this._hasPendingDraws = true;
    }

    _applyStencilTestIfClipping() {
      // This is done via pipeline state in WebGL so this is a no-op
    }

    //////////////////////////////////////////////
    // Shader hooks
    //////////////////////////////////////////////
    uniformNameFromHookKey(key) {
      return key.slice(0, key.indexOf(':'));
    }
    populateHooks(shader, src, shaderType) {
      if (!src.includes('fn main')) return src;

      // Apply some p5-specific preprocessing. WGSL doesn't have preprocessor
      // statements, but some of our shaders might need it, so we add a lightweight
      // way to add code if a hook is augmented. e.g.:
      //   struct Uniforms {
      //   // @p5 ifdef Vertex getWorldInputs
      //     uModelMatrix: mat4f,
      //     uViewMatrix: mat4f,
      //   // @p5 endif
      //   // @p5 ifndef Vertex getWorldInputs
      //     uModelViewMatrix: mat4f,
      //   // @p5 endif
      //   }
      src = src.replace(
        /\/\/ @p5 (ifdef|ifndef) (\w+)\s+(\w+)\n((?:(?!\/\/ @p5)(?:.|\n))*)\/\/ @p5 endif/g,
        (_, condition, hookType, hookName, body) => {
          const target = condition === 'ifdef';
          if (
            (
              !!shader.hooks.modified.vertex[`${hookType} ${hookName}`] ||
              !!shader.hooks.modified.fragment[`${hookType} ${hookName}`]
            ) === target
          ) {
            return body;
          } else {
            return '';
          }
        }
      );

      let [preMain, main, postMain] = src.split(/((?:@(?:vertex|fragment|compute)\s*(?:@workgroup_size\([^)]+\)\s*)?)?fn main[^{]+\{)/);

      const getBuiltinParamName = (mainSrc, builtinName) => {
        const match = new RegExp(`@builtin\\s*\\(\\s*${builtinName}\\s*\\)\\s*(\\w+)\\s*:`).exec(mainSrc);
        return match ? match[1] : null;
      };

      const ensureBuiltinParam = (mainSrc, builtinName, fallbackName, typeName) => {
        const existingName = getBuiltinParamName(mainSrc, builtinName);
        if (existingName) {
          return { mainSrc, argName: existingName };
        }

        const hasParams = /\(\s*\S/.test(mainSrc);
        const injectedMain = mainSrc.replace(
          /\)\s*(->|\{)/,
          `${hasParams ? ', ' : ''}@builtin(${builtinName}) ${fallbackName}: ${typeName}) $1`
        );

        return { mainSrc: injectedMain, argName: fallbackName };
      };

      const getMainStructParameter = (mainSrc) => {
        const match = /fn main\s*\(\s*(\w+)\s*:\s*(\w+)/.exec(mainSrc);
        if (!match) return null;
        return { inputName: match[1], structName: match[2] };
      };

      const getStructBuiltinFieldName = (structName, builtinName) => {
        const structMatch = new RegExp(`struct\\s+${structName}\\s*\\{([^}]*)\\}`, 's').exec(preMain);
        if (!structMatch) return null;
        const fieldMatch = new RegExp(`@builtin\\s*\\(\\s*${builtinName}\\s*\\)\\s*(\\w+)\\s*:`, 's').exec(structMatch[1]);
        return fieldMatch ? fieldMatch[1] : null;
      };

      const appendHookParams = (params, additionalParams) => {
        if (additionalParams.length === 0) return params;
        const hasParams = !/^\(\s*\)$/.test(params);
        return `${params.slice(0, -1)}${hasParams ? ', ' : ''}${additionalParams.join(', ')})`;
      };

      let hookExtraParams = [];
      let hookExtraArgs = [];

      if (shaderType === 'vertex') {
        const ensuredInstance = ensureBuiltinParam(main, 'instance_index', 'instanceID', 'u32');
        main = ensuredInstance.mainSrc;

        const ensuredVertex = ensureBuiltinParam(main, 'vertex_index', '_p5VertexId', 'u32');
        main = ensuredVertex.mainSrc;

        hookExtraParams = ['instanceID: u32', '_p5VertexId: u32'];
        hookExtraArgs = [ensuredInstance.argName, ensuredVertex.argName];
      } else if (shaderType === 'fragment') {
        const directPositionArg = getBuiltinParamName(main, 'position');
        let fragmentPositionArg = directPositionArg;

        if (!fragmentPositionArg) {
          const mainStructParam = getMainStructParameter(main);
          if (mainStructParam) {
            const positionField = getStructBuiltinFieldName(mainStructParam.structName, 'position');
            if (positionField) {
              fragmentPositionArg = `${mainStructParam.inputName}.${positionField}`;
            }
          }
        }

        if (!fragmentPositionArg) {
          const ensuredPosition = ensureBuiltinParam(main, 'position', '_p5FragPos', 'vec4<f32>');
          main = ensuredPosition.mainSrc;
          fragmentPositionArg = ensuredPosition.argName;
        }

        hookExtraParams = ['_p5FragPos: vec4<f32>'];
        hookExtraArgs = [fragmentPositionArg];
      } else if (shaderType === 'compute') {
        const ensuredGlobalId = ensureBuiltinParam(main, 'global_invocation_id', '_p5GlobalId', 'vec3<u32>');
        main = ensuredGlobalId.mainSrc;

        hookExtraParams = ['_p5GlobalId: vec3<u32>'];
        hookExtraArgs = [ensuredGlobalId.argName];
      }

      // Inject hook uniforms as a separate struct at a new binding
      let hookUniformFields = '';
      for (const key in shader.hooks.uniforms) {
        // Skip textures, they don't get added to structs
        if (key.endsWith(': sampler2D')) continue;

        // WGSL format: "name: type"
        hookUniformFields += `  ${key},\n`;
      }

      if (hookUniformFields) {
        // Find the next available binding in group 0
        // Use the source we're currently building (preMain) which has texture bindings. We can't call `fragSrc()`
        // or `vertSrc()` because we may be in one of those calls already, and might infinite loop
        const nextBinding = this.getNextBindingIndex({
          vert: shaderType === 'vertex' ? preMain + (shader.hooks.vertex?.declarations ?? '') + shader.hooks.declarations : shader._vertSrc,
          frag: shaderType === 'fragment' ? preMain + (shader.hooks.fragment?.declarations ?? '') + shader.hooks.declarations : shader._fragSrc,
          compute: shaderType === 'compute' ? preMain + (shader.hooks.compute?.declarations ?? '') + shader.hooks.declarations : shader._computeSrc,
        }, 0);

        // Create HookUniforms struct and binding
        const hookUniformsDecl = `
// Hook Uniforms (from .modify())
struct HookUniforms {
${hookUniformFields}}

@group(0) @binding(${nextBinding}) var<uniform> hooks: HookUniforms;
`;
        // Insert before the first @group binding, or at the end if there are none
        const replaced = preMain.replace(/(@group\(0\)\s+@binding)/, `${hookUniformsDecl}\n$1`);
        if (replaced === preMain) {
          // No @group bindings found in base shader, append to preMain
          preMain = preMain + '\n' + hookUniformsDecl;
        } else {
          preMain = replaced;
        }
      }

      // Handle varying variables by injecting them into VertexOutput and FragmentInput structs
      if (shader.hooks.varyingVariables && shader.hooks.varyingVariables.length > 0) {
        // Generate struct members for varying variables
        let nextLocationIndex = this._getNextAvailableLocation(preMain, shaderType);
        let varyingMembers = '';

        for (const varyingVar of shader.hooks.varyingVariables) {
          // varyingVar is a string like "varName: vec3<f32>"
          const member = `@location(${nextLocationIndex++}) ${varyingVar},`;
          varyingMembers += member + '\n';
        }

        if (shaderType === 'vertex') {
          // Inject into VertexOutput struct
          preMain = preMain.replace(
            /struct\s+VertexOutput\s+\{([^}]*)\}/,
            (match, body) => `struct VertexOutput {${body}\n${varyingMembers}}`
          );
        } else if (shaderType === 'fragment') {
          // Inject into FragmentInput struct
          preMain = preMain.replace(
            /struct\s+FragmentInput\s+\{([^}]*)\}/,
            (match, body) => `struct FragmentInput {${body}\n${varyingMembers}}`
          );
        }
      }

      // Add file-global varying variable declarations
      if (shader.hooks.varyingVariables && shader.hooks.varyingVariables.length > 0) {
        let varyingDeclarations = '';
        for (const varyingVar of shader.hooks.varyingVariables) {
          // varyingVar is a string like "varName: vec3<f32>"
          const [varName, varType] = varyingVar.split(':').map(s => s.trim());
          varyingDeclarations += `var<private> ${varName}: ${varType};\n`;
        }

        // Add declarations before the main function
        preMain += varyingDeclarations;

        if (shaderType === 'vertex') {
          // In vertex shader, copy varying variables to output struct before return
          let copyStatements = '';
          for (const varyingVar of shader.hooks.varyingVariables) {
            const [varName] = varyingVar.split(':').map(s => s.trim());
            copyStatements += `  OUTPUT_VAR.${varName} = ${varName};\n`;
          }

          // Find the output variable name from the return statement and replace OUTPUT_VAR
          const returnMatch = postMain.match(/return\s+(\w+)\s*;/);
          if (returnMatch) {
            const outputVarName = returnMatch[1];
            copyStatements = copyStatements.replace(/OUTPUT_VAR/g, outputVarName);
            // Insert before the return statement
            postMain = postMain.replace(/(return\s+\w+\s*;)/g, `${copyStatements}  $1`);
          }
        } else if (shaderType === 'fragment') {
          // In fragment shader, initialize varying variables from input struct at start of main
          let initStatements = '';
          for (const varyingVar of shader.hooks.varyingVariables) {
            const [varName] = varyingVar.split(':').map(s => s.trim());
            initStatements += `  ${varName} = INPUT_VAR.${varName};\n`;
          }

          const mainStructParam = getMainStructParameter(main);
          if (mainStructParam) {
            const inputVarName = mainStructParam.inputName;
            initStatements = initStatements.replace(/INPUT_VAR/g, inputVarName);
            // Insert after the main function parameter but before any other code (anchored to start)
            postMain = initStatements + postMain;
          }
        }
      }

      // Handle instanceID varying for fragment access
      if (shader.hooks.instanceIDVarying) {
        const { name, declaration, source, interpolation } = shader.hooks.instanceIDVarying;
        const nextLocIndex = this._getNextAvailableLocation(preMain, shaderType);
        const interpAttr = interpolation ? ` @interpolate(${interpolation})` : '';
        const [varName, varType] = declaration.split(':').map(s => s.trim());
        const structMember = `@location(${nextLocIndex})${interpAttr} ${declaration},`;

        if (shaderType === 'vertex') {
          // Inject into VertexOutput struct
          preMain = preMain.replace(
            /struct\s+VertexOutput\s+\{([^}]*)\}/,
            (match, body) => `struct VertexOutput {${body}\n${structMember}}`
          );
          // Add private global
          preMain += `var<private> ${declaration};\n`;
          // Assign from built-in instanceID at start of main()
          postMain = `\n  ${varName} = ${source};\n` + postMain;
          // Copy to output struct before return
          const returnMatch = postMain.match(/return\s+(\w+)\s*;/);
          if (returnMatch) {
            const outputVarName = returnMatch[1];
            postMain = postMain.replace(
              /(return\s+\w+\s*;)/g,
              `${outputVarName}.${varName} = ${varName};\n  $1`
            );
          }
        } else if (shaderType === 'fragment') {
          // Inject into FragmentInput struct
          preMain = preMain.replace(
            /struct\s+FragmentInput\s+\{([^}]*)\}/,
            (match, body) => `struct FragmentInput {${body}\n${structMember}}`
          );
          // Add private global
          preMain += `var<private> ${declaration};\n`;
          // Initialize from input struct at start of main()
          const mainStructParam = getMainStructParameter(main);
          if (mainStructParam) {
            const inputVarName = mainStructParam.inputName;
            postMain = `\n  ${varName} = ${inputVarName}.${varName};\n` + postMain;
          }
        }
      }

      let hooks = '';
      let defines = '';
      if (shader.hooks.declarations) {
        hooks += shader.hooks.declarations + '\n';
      }
      if (shader.hooks[shaderType] && shader.hooks[shaderType].declarations) {
        hooks += shader.hooks[shaderType].declarations + '\n';
      }
      for (const hookDef in shader.hooks.helpers) {
        const [hookType, hookName] = hookDef.split(' ');
        const [_, params, body] = /^(\([^\)]*\))((?:.|\n)*)$/.exec(shader.hooks.helpers[hookDef]);
        if (hookType === 'void') {
          hooks += `fn ${hookName}${params}${body}\n`;
        } else {
          hooks += `fn ${hookName}${params} -> ${hookType}${body}\n`;
        }
      }
      for (const hookDef in shader.hooks[shaderType]) {
        if (hookDef === 'declarations') continue;
        const [hookType, hookName] = hookDef.split(' ');

        // Add a const so that if the shader wants to
        // optimize away the extra function calls in main, it can do so
        defines += `const AUGMENTED_HOOK_${hookName} = ${
          shader.hooks.modified[shaderType][hookDef] ? 'true' : 'false'
        };\n`;

        let [_, params, body] = /^(\([^\)]*\))((?:.|\n)*)$/.exec(shader.hooks[shaderType][hookDef]);

        params = appendHookParams(params, hookExtraParams);

        if (hookType === 'void') {
          hooks += `fn HOOK_${hookName}${params}${body}\n`;
        } else {
          hooks += `fn HOOK_${hookName}${params} -> ${hookType}${body}\n`;
        }
      }

      // Pass stage-specific builtins from main to each hook call.
      // Collect ALL HOOK_ calls (including nested ones) then insert
      // extra args from right to left so position shifts don't
      // invalidate earlier insertion points.
      if (hookExtraArgs.length > 0) {
        const addHookArgs = (src) => {
          const insertions = [];
          let searchIdx = 0;
          let m;
          while ((m = /HOOK_\w+\(/.exec(src.slice(searchIdx))) !== null) {
            const openParen = searchIdx + m.index + m[0].length - 1;
            let pos = openParen + 1;
            let nesting = 1;
            let hasParams = false;
            while (pos < src.length && nesting > 0) {
              if (src[pos] === '(') nesting++;
              else if (src[pos] === ')') {
                nesting--;
                if (nesting === 0) break;
              } else if (/\S/.test(src[pos])) {
                hasParams = true;
              }
              pos++;
            }
            insertions.push({ pos, hasParams });
            searchIdx = openParen + 1;
          }

          insertions.sort((a, b) => b.pos - a.pos);

          let result = src;
          for (const { pos, hasParams } of insertions) {
            const insertion = (hasParams ? ', ' : '') + hookExtraArgs.join(', ');
            result = result.slice(0, pos) + insertion + result.slice(pos);
          }
          return result;
        };
        preMain = addHookArgs(preMain);
        postMain = addHookArgs(postMain);
      }

      return preMain + '\n' + defines + hooks + main + postMain;
    }

    _getNextAvailableLocation(shaderSource, shaderType) {
      // Parse existing struct to find the highest @location number
      let maxLocation = -1;
      const structName = shaderType === 'vertex' ? 'VertexOutput' : 'FragmentInput';

      // Find the struct definition
      const structMatch = shaderSource.match(new RegExp(`struct\\s+${structName}\\s*\\{([^}]*)\\}`, 's'));
      if (structMatch) {
        const structBody = structMatch[1];

        // Find all @location(N) declarations
        const locationMatches = structBody.matchAll(/@location\((\d+)\)/g);
        for (const match of locationMatches) {
          const locationNum = parseInt(match[1]);
          if (locationNum > maxLocation) {
            maxLocation = locationNum;
          }
        }
      }

      return maxLocation + 1;
    }

    getShaderHookTypes(shader, hookName) {
      // Create mapping from WGSL types to DataType entries
      const wgslToDataType = {
        'f32': DataType.float1,
        'vec2<f32>': DataType.float2,
        'vec3<f32>': DataType.float3,
        'vec4<f32>': DataType.float4,
        'vec2f': DataType.float2,
        'vec3f': DataType.float3,
        'vec4f': DataType.float4,
        'i32': DataType.int1,
        'vec2<i32>': DataType.int2,
        'vec3<i32>': DataType.int3,
        'vec4<i32>': DataType.int4,
        'bool': DataType.bool1,
        'vec2<bool>': DataType.bool2,
        'vec3<bool>': DataType.bool3,
        'vec4<bool>': DataType.bool4,
        'mat2x2<f32>': DataType.mat2,
        'mat3x3<f32>': DataType.mat3,
        'mat4x4<f32>': DataType.mat4,
        'texture_2d<f32>': DataType.sampler2D
      };

      let fullSrc = shader._vertSrc;
      let body = shader.hooks.vertex[hookName];
      if (!body) {
        body = shader.hooks.fragment[hookName];
        fullSrc = shader._fragSrc;
      }
      if (!body) {
        body = shader.hooks.compute[hookName];
        fullSrc = shader._computeSrc;
      }
      if (!body) {
        throw new Error(`Can't find hook ${hookName}!`);
      }
      const nameParts = hookName.split(/\s+/g);
      const functionName = nameParts.pop();
      const returnType = nameParts.pop();
      const returnQualifiers = [...nameParts];
      const parameterMatch = /\(([^\)]*)\)/.exec(body);
      if (!parameterMatch) {
        throw new Error(`Couldn't find function parameters in hook body:\n${body}`);
      }

      const structProperties = structName => {
        // WGSL struct parsing: struct StructName { field1: Type, field2: Type }
        const structDefMatch = new RegExp(`struct\\s+${structName}\\s*{([^}]*)}`).exec(fullSrc);
        if (!structDefMatch) return undefined;
        const properties = [];

        // Parse WGSL struct fields (e.g., "texCoord: vec2<f32>,")
        for (const fieldSrc of structDefMatch[1].split(',')) {
          const trimmed = fieldSrc.trim();
          if (!trimmed) continue;

          // Remove location decorations and parse field
          // Format: [@location(N)] fieldName: Type
          const fieldMatch = /(?:@location\([^)]*\)\s*)?(\w+)\s*:\s*([^,\s]+)/.exec(trimmed);
          if (!fieldMatch) continue;

          const name = fieldMatch[1];
          let typeName = fieldMatch[2];

          const dataType = wgslToDataType[typeName] || null;

          const typeProperties = structProperties(typeName);
          properties.push({
            name,
            type: {
              typeName: typeName, // Keep native WGSL type name
              qualifiers: [],
              properties: typeProperties,
              dataType: dataType
            }
          });
        }
        return properties;
      };

      const parameters = parameterMatch[1].split(',').map(paramString => {
        // WGSL function parameters: name: type or name: binding<type>
        const trimmed = paramString.trim();
        if (!trimmed) return null;

        const parts = trimmed.split(':').map(s => s.trim());
        if (parts.length !== 2) return null;

        const name = parts[0];
        let typeName = parts[1];

        // Handle texture bindings like "texture_2d<f32>" -> sampler2D DataType
        if (typeName.includes('texture_2d')) {
          typeName = 'texture_2d<f32>';
        }

        const dataType = wgslToDataType[typeName] || null;

        const properties = structProperties(typeName);
        return {
          name,
          type: {
            typeName: typeName, // Keep native WGSL type name
            qualifiers: [],
            properties,
            dataType: dataType
          }
        };
      }).filter(Boolean);

      // Convert WGSL return type to DataType
      const returnDataType = wgslToDataType[returnType] || null;

      return {
        name: functionName,
        returnType: {
          typeName: returnType, // Keep native WGSL type name
          qualifiers: returnQualifiers,
          properties: structProperties(returnType),
          dataType: returnDataType
        },
        parameters
      };
    }

    //////////////////////////////////////////////
    // Buffer management for pixel reading
    //////////////////////////////////////////////

    _ensurePixelReadBuffer(requiredSize) {
      // Create or resize staging buffer if needed
      if (!this.pixelReadBuffer || this.pixelReadBufferSize < requiredSize) {
        // Clean up old buffer
        if (this.pixelReadBuffer) {
          this.flushDraw();
          this.pixelReadBuffer.destroy();
        }

        // Create new buffer with padding to avoid frequent recreations
        // Scale by 2 to ensure integer size and reasonable headroom
        const bufferSize = Math.max(requiredSize, this.pixelReadBufferSize * 2);
        this.pixelReadBuffer = this.device.createBuffer({
          size: bufferSize,
          usage: GPUBufferUsage.COPY_DST | GPUBufferUsage.MAP_READ,
        });
        this.pixelReadBufferSize = bufferSize;
      }
      return this.pixelReadBuffer;
    }

    _alignBytesPerRow(bytesPerRow) {
      // WebGPU requires bytesPerRow to be a multiple of 256 bytes for texture-to-buffer copies
      return Math.ceil(bytesPerRow / 256) * 256;
    }

    //////////////////////////////////////////////
    // Framebuffer methods
    //////////////////////////////////////////////

    defaultFramebufferAlpha() {
      return true
    }

    defaultFramebufferAntialias() {
      return this._pInst._webgpuAttributes?.antialias !== false;
    }

    supportsFramebufferAntialias() {
      return true;
    }

    createFramebufferResources(framebuffer) {
    }

    validateFramebufferFormats(framebuffer) {
      if (![
        constants.UNSIGNED_BYTE,
        constants.FLOAT,
        constants.HALF_FLOAT
      ].includes(framebuffer.format)) {
        console.warn(
          'Unknown Framebuffer format. ' +
            'Please use UNSIGNED_BYTE, FLOAT, or HALF_FLOAT. ' +
            'Defaulting to UNSIGNED_BYTE.'
        );
        framebuffer.format = constants.UNSIGNED_BYTE;
      }

      if (framebuffer.useDepth && ![
        constants.UNSIGNED_INT,
        constants.FLOAT
      ].includes(framebuffer.depthFormat)) {
        console.warn(
          'Unknown Framebuffer depth format. ' +
            'Please use UNSIGNED_INT or FLOAT. Defaulting to FLOAT.'
        );
        framebuffer.depthFormat = constants.FLOAT;
      }
    }

    recreateFramebufferTextures(framebuffer) {
      this.flushDraw();
      // Clean up existing textures
      if (framebuffer.colorTexture && framebuffer.colorTexture.destroy) {
        const tex = framebuffer.colorTexture;
        this._postSubmitCallbacks.push(() => tex.destroy());
        framebuffer.colorTextureView = null;
      }
      if (framebuffer.aaColorTexture && framebuffer.aaColorTexture.destroy) {
        const tex = framebuffer.aaColorTexture;
        this._postSubmitCallbacks.push(() => tex.destroy());
        framebuffer.aaColorTextureView = null;
      }
      if (framebuffer.depthTexture && framebuffer.depthTexture.destroy) {
        const tex = framebuffer.depthTexture;
        this._postSubmitCallbacks.push(() => tex.destroy());
        framebuffer.depthTextureView = null;
      }
      if (framebuffer.aaDepthTexture && framebuffer.aaDepthTexture.destroy) {
        const tex = framebuffer.aaDepthTexture;
        this._postSubmitCallbacks.push(() => tex.destroy());
        framebuffer.aaDepthTextureView = null;
      }

      const baseDescriptor = {
        size: {
          width: framebuffer.width * framebuffer.density,
          height: framebuffer.height * framebuffer.density,
          depthOrArrayLayers: 1,
        },
        format: this._getWebGPUColorFormat(framebuffer),
      };

      // Create non-multisampled texture for texture binding (always needed)
      const colorTextureDescriptor = {
        ...baseDescriptor,
        usage: GPUTextureUsage.RENDER_ATTACHMENT |
               GPUTextureUsage.TEXTURE_BINDING |
               GPUTextureUsage.COPY_SRC |
               (framebuffer._useCanvasFormat ? GPUTextureUsage.COPY_DST : 0),
        sampleCount: 1,
      };
      framebuffer.colorTexture = this.device.createTexture(colorTextureDescriptor);
      framebuffer.colorTextureView = framebuffer.colorTexture.createView();

      // Create multisampled texture for rendering if antialiasing is enabled
      if (framebuffer.antialias) {
        const aaColorTextureDescriptor = {
          ...baseDescriptor,
          usage: GPUTextureUsage.RENDER_ATTACHMENT,
          sampleCount: this._getValidSampleCount(framebuffer.antialiasSamples),
        };
        framebuffer.aaColorTexture = this.device.createTexture(aaColorTextureDescriptor);
        framebuffer.aaColorTextureView = framebuffer.aaColorTexture.createView();
      }

      if (framebuffer.useDepth) {
        const depthBaseDescriptor = {
          size: {
            width: framebuffer.width * framebuffer.density,
            height: framebuffer.height * framebuffer.density,
            depthOrArrayLayers: 1,
          },
          format: this._getWebGPUDepthFormat(framebuffer),
        };

        // Create non-multisampled depth texture for texture binding (always needed)
        const depthTextureDescriptor = {
          ...depthBaseDescriptor,
          usage: GPUTextureUsage.RENDER_ATTACHMENT |
                 GPUTextureUsage.TEXTURE_BINDING |
                 (framebuffer._useCanvasFormat ? GPUTextureUsage.COPY_DST : 0),
          sampleCount: 1,
        };
        framebuffer.depthTexture = this.device.createTexture(depthTextureDescriptor);
        framebuffer.depthTextureView = framebuffer.depthTexture.createView();

        // Create multisampled depth texture for rendering if antialiasing is enabled
        if (framebuffer.antialias) {
          const aaDepthTextureDescriptor = {
            ...depthBaseDescriptor,
            usage: GPUTextureUsage.RENDER_ATTACHMENT,
            sampleCount: this._getValidSampleCount(framebuffer.antialiasSamples),
          };
          framebuffer.aaDepthTexture = this.device.createTexture(aaDepthTextureDescriptor);
          framebuffer.aaDepthTextureView = framebuffer.aaDepthTexture.createView();
        }
      }

      // Clear the framebuffer textures after creation
      this._clearFramebufferTextures(framebuffer);
    }

    _clearFramebufferTextures(framebuffer) {
      this._finishActiveRenderPass();
      const commandEncoder = this.device.createCommandEncoder();

      // Clear the color texture (and multisampled texture if it exists)
      const colorAttachment = {
        view: framebuffer.aaColorTexture
          ? framebuffer.aaColorTextureView
          : framebuffer.colorTextureView,
        loadOp: "clear",
        storeOp: "store",
        clearValue: { r: 0, g: 0, b: 0, a: 0 },
        resolveTarget: framebuffer.aaColorTexture
          ? framebuffer.colorTextureView
          : undefined,
      };

      // Clear the depth texture if it exists
      const depthTexture = framebuffer.aaDepthTexture || framebuffer.depthTexture;
      const depthStencilAttachment = depthTexture ? {
        view: framebuffer.aaDepthTexture
          ? framebuffer.aaDepthTextureView
          : framebuffer.depthTextureView,
        depthLoadOp: "clear",
        depthStoreOp: "store",
        depthClearValue: 1.0,
        stencilLoadOp: "clear",
        stencilStoreOp: "store",
        depthReadOnly: false,
        stencilReadOnly: false,
      } : undefined;

      const renderPassDescriptor = {
        colorAttachments: [colorAttachment],
        depthStencilAttachment: depthStencilAttachment,
      };

      const passEncoder = commandEncoder.beginRenderPass(renderPassDescriptor);
      passEncoder.end();

      this._pendingCommandEncoders.push(commandEncoder.finish());
      this._hasPendingDraws = true;
    }

    _getFramebufferColorTextureView(framebuffer) {
      if (framebuffer.colorTexture) {
        return framebuffer.colorTextureView;
      }
      return null;
    }

    createFramebufferTextureHandle(framebufferTexture) {
      const src = framebufferTexture;
      let renderer = this;
      return {
        get view() {
          return renderer._getFramebufferColorTextureView(src.framebuffer);
        },
        get gpuTexture() {
          return src.framebuffer.colorTexture;
        }
      };
    }

    // Maps a plain JS value to the WGSL type string that represents it in a struct.
    _jsValueToWgslType(value) {
      if (typeof value === 'number') return 'f32';
      // Duck typing instead of instanceof to avoid importing a separate
      // copy of the Color/Vector classes
      if (value?.isVector) {
        if (value.dimensions === 2) return 'vec2f';
        if (value.dimensions === 3) return 'vec3f';
        if (value.dimensions === 4) return 'vec4f';
        throw new Error(`Unsupported vector dimension ${value.dimensions} for struct storage field`);
      }
      if (value?.isColor) {
        return 'vec4f';
      }
      if (Array.isArray(value)) {
        if (value.length === 2) return 'vec2f';
        if (value.length === 3) return 'vec3f';
        if (value.length === 4) return 'vec4f';
        throw new Error(`Unsupported array length ${value.length} for struct storage field`);
      }
      throw new Error(`Unsupported value type ${typeof value} for struct storage field`);
    }

    // Infers a struct schema from the first element of a struct array.
    //
    // Returns { fields, stride, structBody } where:
    //   fields: field has the _packField interface (baseType, size, offset, packInPlace) plus:
    //     name: string - JS property name
    //     dim:  number - float component count, used when creating StrandsNodes
    //   structBody: everything inside the  { ... } of a WGSL struct definition
    //   stride: how many bytes are reserved for this struct in the buffer
    _inferStructSchema(firstElement) {
      const entries = Object.entries(firstElement);

      if (!p5.disableFriendlyErrors) {
        for (const [name, value] of entries) {
          if (
            value !== null &&
            typeof value === 'object' &&
            !Array.isArray(value) &&
            // Duck typing instead of instanceof to avoid importing a separate
            // copy of the Color/Vector classes
            !value?.isVector &&
            !value?.isColor
          ) {
            p5._friendlyError(
              `The "${name}" property in your storage data contains a nested object. ` +
              `Make sure you only use properties with numbers, arrays of numbers, or p5.Vector.`,
              'createStorage'
            );
          }
        }
      }

      const fieldLines = entries.map(([name, value]) =>
        `  ${name}: ${this._jsValueToWgslType(value)},`
      ).join('\n');
      const structBody = `{\n${fieldLines}\n}`;
      const elements = this._parseStruct(`struct _Tmp ${structBody}`, '_Tmp');

      let maxEnd = 0;
      let maxAlign = 1;
      const fields = entries.map(([name, value]) => {
        const el = elements[name];
        maxEnd = Math.max(maxEnd, el.offsetEnd);
        // Alignment for scalars/vectors: <=4 -> 4, <=8 -> 8, else 16
        const align = el.size <= 4 ? 4 : el.size <= 8 ? 8 : 16;
        maxAlign = Math.max(maxAlign, align);
        // Track original JS type for reconstruction during readback
        const kind = value?.isVector ? 'vector'
          : value?.isColor ? 'color'
          : undefined;
        return {
          name,
          baseType: el.baseType,
          size: el.size,
          offset: el.offset,
          packInPlace: el.packInPlace ?? false,
          dim: el.size / 4,
          kind,
        };
      });

      const stride = Math.ceil(maxEnd / maxAlign) * maxAlign;
      return { fields, stride, structBody };
    }

    // Packs an array of plain objects into a Float32Array using the given struct schema.
    // Reuses _packField so layout rules match uniform packing exactly.
    _packStructArray(data, schema) {
      const { fields, stride } = schema;
      const totalBytes = Math.max(data.length * stride, 16);
      const alignedBytes = Math.ceil(totalBytes / 16) * 16;
      const buffer = new ArrayBuffer(alignedBytes);
      const floatView = new Float32Array(buffer);
      const dataView = new DataView(buffer);
      for (let i = 0; i < data.length; i++) {
        const item = data[i];
        const baseOffset = i * stride;
        for (const field of fields) {
          this._packField(field, item[field.name], floatView, dataView, baseOffset);
        }
      }
      return floatView;
    }

    // Inverse of _packStructArray reads packed buffer back into plain JS objects
    // using the same schema layout - fields, stride and offsets
    _unpackStructArray(floatView, schema) {
      const { fields, stride } = schema;
      const dataView = new DataView(floatView.buffer);
      const count = Math.floor(floatView.byteLength / stride);
      const result = [];

      for (let i = 0; i < count; i++) {
        const item = {};
        const baseOffset = i * stride;
        for (const field of fields) {
          const byteOffset = baseOffset + field.offset;
          const n = field.size / 4;

          if (field.baseType === 'u32') {
            if (n === 1) {
              item[field.name] = dataView.getUint32(byteOffset, true);
            } else {
              item[field.name] = Array.from({ length: n }, (_, j) =>
                dataView.getUint32(byteOffset + j * 4, true)
              );
            }
          } else if (field.baseType === 'i32') {
            if (n === 1) {
              item[field.name] = dataView.getInt32(byteOffset, true);
            } else {
              item[field.name] = Array.from({ length: n }, (_, j) =>
                dataView.getInt32(byteOffset + j * 4, true)
              );
            }
          } else {
            const idx = byteOffset / 4;
            if (n === 1) {
              item[field.name] = floatView[idx];
            } else {
              const values = Array.from(floatView.slice(idx, idx + n));
              if (field.kind === 'vector') {
                item[field.name] = this._pInst.createVector(...values);
              } else if (field.kind === 'color') {
                // Color was packed as normalized RGBA [0-1] via _getRGBA([1,1,1,1])
                // Scale back to the current colorMode range
                const maxes = this.states.colorMaxes[this.states.colorMode];
                item[field.name] = this._pInst.color(
                  values[0] * maxes[0], values[1] * maxes[1],
                  values[2] * maxes[2], values[3] * maxes[3]
                );
              } else {
                item[field.name] = values;
              }
            }
          }
        }
        result.push(item);
      }

      return result;
    }

    createStorage(dataOrCount) {
      const device = this.device;

      // Struct array: an array of plain objects
      if (Array.isArray(dataOrCount) && dataOrCount.length > 0 &&
          typeof dataOrCount[0] === 'object' && !Array.isArray(dataOrCount[0])) {
        if (!p5.disableFriendlyErrors && dataOrCount.length > 1) {
          const firstKeys = Object.keys(dataOrCount[0]);
          let warned = false;
          for (let i = 1; i < dataOrCount.length; i++) {
            const el = dataOrCount[i];
            const elKeys = Object.keys(el);
            const sameKeys = firstKeys.length === elKeys.length &&
              firstKeys.every((k, j) => k === elKeys[j]);
            if (!sameKeys) {
              p5._friendlyError(
                `Element ${i} has different fields than element 0. ` +
                `All elements should have the same properties.`,
                'createStorage'
              );
              break;
            }
            for (const key of firstKeys) {
              const firstType = this._jsValueToWgslType(dataOrCount[0][key]);
              const elType = this._jsValueToWgslType(el[key]);
              if (firstType !== elType) {
                p5._friendlyError(
                  `The "${key}" property of element ${i} has type ${elType} ` +
                  `but element 0 has type ${firstType}. Proporties should have the same type across all elements.`,
                  'createStorage'
                );
                warned = true;
                break;
              }
            }
            if (warned) break;
          }
        }
        const schema = this._inferStructSchema(dataOrCount[0]);
        const packed = this._packStructArray(dataOrCount, schema);
        const size = packed.byteLength;
        const buffer = device.createBuffer({
          size,
          usage: GPUBufferUsage.STORAGE | GPUBufferUsage.COPY_DST | GPUBufferUsage.COPY_SRC,
          mappedAtCreation: true,
        });
        new Float32Array(buffer.getMappedRange()).set(packed);
        buffer.unmap();
        const storageBuffer = new StorageBuffer(buffer, size, this, schema);
        this._storageBuffers.add(storageBuffer);
        return storageBuffer;
      }

      // Determine buffer size and initial data
      let size, initialData;
      if (typeof dataOrCount === 'number') {
        // createStorage(count) - zero-initialized
        size = dataOrCount * 4; // floats are 4 bytes
        initialData = new Float32Array(dataOrCount);
      } else {
        // createStorage(array) - from data
        if (dataOrCount instanceof Float32Array) {
          initialData = dataOrCount;
        } else if (Array.isArray(dataOrCount)) {
          initialData = new Float32Array(dataOrCount);
        } else {
          throw new Error('createStorage expects a number or array/Float32Array');
        }
        size = initialData.byteLength;
      }

      // Align to 16 bytes (WGSL storage buffer alignment requirement)
      size = Math.ceil(size / 16) * 16;

      // Create storage buffer with STORAGE | COPY_DST | COPY_SRC usage
      const buffer = device.createBuffer({
        size,
        usage: GPUBufferUsage.STORAGE | GPUBufferUsage.COPY_DST | GPUBufferUsage.COPY_SRC,
        mappedAtCreation: initialData.length > 0
      });

      // Write initial data if provided
      if (initialData.length > 0) {
        const mapping = new Float32Array(buffer.getMappedRange());
        mapping.set(initialData);
        buffer.unmap();
      }

      const storageBuffer = new StorageBuffer(buffer, size, this);

      // Track for cleanup
      this._storageBuffers.add(storageBuffer);

      return storageBuffer;
    }

    _getWebGPUColorFormat(framebuffer) {
      if (framebuffer.format === constants.FLOAT) {
        return framebuffer.channels === RGBA ? 'rgba32float' : 'rgba32float';
      } else if (framebuffer.format === constants.HALF_FLOAT) {
        return framebuffer.channels === RGBA ? 'rgba16float' : 'rgba16float';
      } else {
        // Framebuffer with _useCanvasFormat should match canvas presentation format
        if (framebuffer._useCanvasFormat) {
          return this.presentationFormat;
        }
        // Other framebuffers use standard RGBA format
        return framebuffer.channels === RGBA ? 'rgba8unorm' : 'rgba8unorm';
      }
    }

    _getWebGPUDepthFormat(framebuffer) {
      if (framebuffer._useCanvasFormat) {
        return this.depthFormat;
      }
      if (framebuffer.useStencil) {
        return framebuffer.depthFormat === constants.FLOAT ? 'depth32float-stencil8' : 'depth24plus-stencil8';
      } else {
        return framebuffer.depthFormat === constants.FLOAT ? 'depth32float' : 'depth24plus';
      }
    }

    _deleteFramebufferTexture(texture) {
      this.flushDraw();
      const handle = texture.rawTexture();
      if (handle.texture && handle.texture.destroy) {
        const tex = handle.texture;
        this._postSubmitCallbacks.push(() => tex.destroy());
      }
      this.textures.delete(texture);
    }

    deleteFramebufferTextures(framebuffer) {
      this._deleteFramebufferTexture(framebuffer.color)
      if (framebuffer.depth) this._deleteFramebufferTexture(framebuffer.depth);
    }

    deleteFramebufferResources(framebuffer) {
      this.flushDraw();
      if (framebuffer.colorTexture && framebuffer.colorTexture.destroy) {
        const tex = framebuffer.colorTexture;
        this._postSubmitCallbacks.push(() => tex.destroy());
      }
      if (framebuffer.depthTexture && framebuffer.depthTexture.destroy) {
        const tex = framebuffer.depthTexture;
        this._postSubmitCallbacks.push(() => tex.destroy());
      }
      if (framebuffer.aaDepthTexture && framebuffer.aaDepthTexture.destroy) {
        const tex = framebuffer.aaDepthTexture;
        this._postSubmitCallbacks.push(() => tex.destroy());
      }
    }

    getFramebufferToBind(framebuffer) {
    }

    updateFramebufferTexture(framebuffer, property) {
      // No-op for WebGPU since antialiasing is handled at pipeline level
    }

    bindFramebuffer(framebuffer) {}

    framebufferYScale() {
      return 1;
    }

    async readFramebufferPixels(framebuffer) {
      this.flushDraw();
      // await this.finishDraw();
      // Ensure all pending GPU work is complete before reading pixels
      // await this.queue.onSubmittedWorkDone();

      const width = framebuffer.width * framebuffer.density;
      const height = framebuffer.height * framebuffer.density;
      const bytesPerPixel = 4;
      const unalignedBytesPerRow = width * bytesPerPixel;
      const alignedBytesPerRow = this._alignBytesPerRow(unalignedBytesPerRow);
      const bufferSize = alignedBytesPerRow * height;

      // const stagingBuffer = this._ensurePixelReadBuffer(bufferSize);
      const stagingBuffer = this.device.createBuffer({
        size: bufferSize,
        usage: GPUBufferUsage.COPY_DST | GPUBufferUsage.MAP_READ,
      });

      const commandEncoder = this.device.createCommandEncoder();
      commandEncoder.copyTextureToBuffer(
        {
          texture: framebuffer.colorTexture,
          origin: { x: 0, y: 0, z: 0 },
          mipLevel: 0,
          aspect: 'all'
        },
        { buffer: stagingBuffer, bytesPerRow: alignedBytesPerRow, rowsPerImage: height },
        { width, height, depthOrArrayLayers: 1 }
      );

      this.device.queue.submit([commandEncoder.finish()]);

      // Wait for the copy operation to complete
      // await this.queue.onSubmittedWorkDone();

      await stagingBuffer.mapAsync(GPUMapMode.READ, 0, bufferSize);
      const mappedRange = stagingBuffer.getMappedRange(0, bufferSize);

      // If alignment was needed, extract the actual pixel data
      let result;
      if (alignedBytesPerRow === unalignedBytesPerRow) {
        result = new Uint8Array(mappedRange.slice(0, width * height * bytesPerPixel));
        stagingBuffer.unmap();
      } else {
        // Need to extract pixel data from aligned buffer
        result = new Uint8Array(width * height * bytesPerPixel);
        const mappedData = new Uint8Array(mappedRange);
        for (let y = 0; y < height; y++) {
          const srcOffset = y * alignedBytesPerRow;
          const dstOffset = y * unalignedBytesPerRow;
          result.set(mappedData.subarray(srcOffset, srcOffset + unalignedBytesPerRow), dstOffset);
        }
        stagingBuffer.unmap();
      }

      this._ensurePixelsAreRGBA(framebuffer, result);

      return result;
    }

    async readFramebufferPixel(framebuffer, x, y) {
      this.flushDraw();
      // await this.finishDraw();
      // Ensure all pending GPU work is complete before reading pixels
      // await this.queue.onSubmittedWorkDone();

      const bytesPerPixel = 4;
      const alignedBytesPerRow = this._alignBytesPerRow(bytesPerPixel);
      const bufferSize = alignedBytesPerRow;

      const stagingBuffer = this._ensurePixelReadBuffer(bufferSize);

      const commandEncoder = this.device.createCommandEncoder();
      commandEncoder.copyTextureToBuffer(
        {
          texture: framebuffer.colorTexture,
          origin: { x, y, z: 0 }
        },
        { buffer: stagingBuffer, bytesPerRow: alignedBytesPerRow },
        { width: 1, height: 1, depthOrArrayLayers: 1 }
      );

      this.device.queue.submit([commandEncoder.finish()]);

      await stagingBuffer.mapAsync(GPUMapMode.READ, 0, bufferSize);
      const mappedRange = stagingBuffer.getMappedRange(0, bufferSize);
      const pixelData = new Uint8Array(mappedRange);
      const result = [pixelData[0], pixelData[1], pixelData[2], pixelData[3]];


      this._ensurePixelsAreRGBA(framebuffer, result);

      stagingBuffer.unmap();
      return result;
    }

    async readFramebufferRegion(framebuffer, x, y, w, h) {
      this.flushDraw();
      // await this.finishDraw();
      // const wasActive = this.activeFramebuffer() === framebuffer;
      // if (wasActive) {
        // framebuffer.end();
        // this.flushDraw()
      // }
      // Ensure all pending GPU work is complete before reading pixels
      // await this.queue.onSubmittedWorkDone();

      const width = w * framebuffer.density;
      const height = h * framebuffer.density;
      const bytesPerPixel = 4;
      const unalignedBytesPerRow = width * bytesPerPixel;
      const alignedBytesPerRow = this._alignBytesPerRow(unalignedBytesPerRow);
      const bufferSize = alignedBytesPerRow * height;

      const stagingBuffer = this._ensurePixelReadBuffer(bufferSize);

      const commandEncoder = this.device.createCommandEncoder();
      commandEncoder.copyTextureToBuffer(
        {
          texture: framebuffer.colorTexture,
          mipLevel: 0,
          origin: { x: x * framebuffer.density, y: y * framebuffer.density, z: 0 }
        },
        { buffer: stagingBuffer, bytesPerRow: alignedBytesPerRow },
        { width, height, depthOrArrayLayers: 1 }
      );

      this.device.queue.submit([commandEncoder.finish()]);

      await stagingBuffer.mapAsync(GPUMapMode.READ, 0, bufferSize);
      const mappedRange = stagingBuffer.getMappedRange(0, bufferSize);

      let pixelData;
      if (alignedBytesPerRow === unalignedBytesPerRow) {
        pixelData = new Uint8Array(mappedRange.slice(0, width * height * bytesPerPixel));
      } else {
        // Need to extract pixel data from aligned buffer
        pixelData = new Uint8Array(width * height * bytesPerPixel);
        const mappedData = new Uint8Array(mappedRange);
        for (let y = 0; y < height; y++) {
          const srcOffset = y * alignedBytesPerRow;
          const dstOffset = y * unalignedBytesPerRow;
          pixelData.set(mappedData.subarray(srcOffset, srcOffset + unalignedBytesPerRow), dstOffset);
        }
      }
      this._ensurePixelsAreRGBA(framebuffer, pixelData);

      // WebGPU doesn't need vertical flipping unlike WebGL
      const region = new Image(width, height);
      region.imageData = region.canvas.getContext('2d').createImageData(width, height);
      region.imageData.data.set(pixelData);
      region.pixels = region.imageData.data;
      region.updatePixels();

      if (framebuffer.density !== 1) {
        region.pixelDensity(framebuffer.density);
      }

      stagingBuffer.unmap();
      // if (wasActive) framebuffer.begin();
      return region;
    }

    updateFramebufferPixels(framebuffer) {
      const width = framebuffer.width * framebuffer.density;
      const height = framebuffer.height * framebuffer.density;
      const bytesPerPixel = 4;

      const expectedLength = width * height * bytesPerPixel;
      if (!framebuffer.pixels || framebuffer.pixels.length !== expectedLength) {
        throw new Error(
          'The pixels array has not been set correctly. Please call loadPixels() before updatePixels().'
        );
      }

      this.device.queue.writeTexture(
        { texture: framebuffer.colorTexture },
        framebuffer.pixels,
        {
          bytesPerRow: width * bytesPerPixel,
          rowsPerImage: height
        },
        { width, height, depthOrArrayLayers: 1 }
      );
    }

    //////////////////////////////////////////////
    // Main canvas pixel methods
    //////////////////////////////////////////////

    _ensurePixelsAreRGBA(framebuffer, result) {
      // Convert BGRA to RGBA if reading from canvas-format framebuffer on BGRA systems
      if (framebuffer._useCanvasFormat && this.presentationFormat === 'bgra8unorm') {
        this._convertBGRtoRGB(result);
      }
    }

    _convertBGRtoRGB(pixelData) {
      for (let i = 0; i < pixelData.length; i += 4) {
        const temp = pixelData[i];
        pixelData[i] = pixelData[i + 2];
        pixelData[i + 2] = temp;
      }
    }

    async loadPixels() {
      this._promoteToFramebuffer();
      await this.mainFramebuffer.loadPixels();
      this.pixels = this.mainFramebuffer.pixels.slice();
    }

    async get(x, y, w, h) {
      this._promoteToFramebuffer();
      return this.mainFramebuffer.get(x, y, w, h);
    }

    filter(...args) {
      // If no custom framebuffer is active, promote to mainFramebuffer
      if (!this.activeFramebuffer()) {
        this._promoteToFramebuffer();
      }

      return super.filter(...args);
    }


    baseFilterShader() {
      if (!this._baseFilterShader) {
        this._baseFilterShader = new Shader(
          this,
          baseFilterVertexShader,
          baseFilterFragmentShader,
          {
            vertex: {},
            fragment: {
              "vec4<f32> getColor": `(inputs: FilterInputs, canvasContent: texture_2d<f32>, canvasContent_sampler: sampler) -> vec4<f32> {
                return textureSample(tex, tex_sampler, inputs.texCoord);
              }`,
            },
            hookAliases: {
              'getColor': ['filterColor'],
            },
          }
        );
      }
      return this._baseFilterShader;
    }

    baseComputeShader() {
      if (!this._baseComputeShader) {
        this._baseComputeShader = new Shader(
          this,
          baseComputeShader,
          {
            compute: {
              'void iteration': '(index: vec3<i32>) {}',
            },
          }
        );
      }
      return this._baseComputeShader;
    }

    /*
     * WebGPU-specific implementation of imageLight shader creation
     */
    _createImageLightShader(type) {
      if (type === 'diffused') {
        return this._pInst.createShader(
          imageLightVertexShader,
          imageLightDiffusedFragmentShader
        );
      } else if (type === 'specular') {
        return this._pInst.createShader(
          imageLightVertexShader,
          imageLightSpecularFragmentShader
        );
      }
      throw new Error(`Unknown imageLight shader type: ${type}`);
    }

    /*
     * WebGPU-specific implementation of mipmap texture creation
     */
    _createMipmapTexture(levels) {
      return new MipmapTexture(this, levels, {});
    }

    /*
     * Prepare WebGPU texture to accumulate mip levels directly
     */
    _prepareMipmapData(size, mipLevels) {
      // Create WebGPU texture with mipmaps upfront
      const textureDescriptor = {
        size: {
          width: size,
          height: size,
          depthOrArrayLayers: 1,
        },
        mipLevelCount: mipLevels,
        format: 'rgba8unorm',
        usage: GPUTextureUsage.TEXTURE_BINDING | GPUTextureUsage.COPY_DST | GPUTextureUsage.RENDER_ATTACHMENT,
      };

      const gpuTexture = this.device.createTexture(textureDescriptor);

      return {
        gpuTexture,
        size,
        mipLevels,
        format: 'rgba8unorm'
      };
    }

    /*
     * Copy framebuffer content directly to WebGPU texture mip level
     */
    _accumulateMipLevel(framebuffer, mipmapData, mipLevel, width, height) {
      this.flushDraw();
      // Copy from framebuffer texture to the mip level
      const commandEncoder = this.device.createCommandEncoder();

      // Get the underlying WebGPU texture from the framebuffer
      const sourceTexture = framebuffer.color.rawTexture().texture;

      commandEncoder.copyTextureToTexture(
        {
          texture: sourceTexture,
          origin: { x: 0, y: 0, z: 0 },
        },
        {
          texture: mipmapData.gpuTexture,
          mipLevel: mipLevel,
          origin: { x: 0, y: 0, z: 0 },
        },
        {
          width: width,
          height: height,
          depthOrArrayLayers: 1,
        }
      );

      this.device.queue.submit([commandEncoder.finish()]);
    }

    /*
     * Create final MipmapTexture from WebGPU texture
     */
    _finalizeMipmapTexture(mipmapData) {
      // Create a MipmapTexture that wraps the pre-built WebGPU texture
      return new MipmapTexture(this, mipmapData, {});
    }

    createMipmapTextureHandle({ gpuTexture, format, dataType, width, height }) {
      // WebGPU always uses pre-built GPU textures for mipmaps
      return {
        texture: gpuTexture,
        view: gpuTexture.createView(),
        glFormat: format || 'rgba8unorm',
        glDataType: dataType || 'uint8'
      };
    }

    compute(shader, x, y = 1, z = 1) {
      if (shader.shaderType !== 'compute') {
        throw new Error('compute() can only be called with a compute shader');
      }

      this._finishActiveRenderPass();

      // Ensure shader is initialized and finalized
      if (!shader._compiled) {
        shader.init();
      }

      // Set default uniforms
      shader.setDefaultUniforms();
      shader.setUniform('uTotalCount', [x, y, z]);

      // Calculate optimal workgroup size (8x8x1 = 64 threads per workgroup)
      const WORKGROUP_SIZE_X = 8;
      const WORKGROUP_SIZE_Y = 8;
      const WORKGROUP_SIZE_Z = 1;

      // auto spreading: if any dimension is too large or for performance optimization,
      // spread total iteration count across dimensions
      const totalIterations = x * y * z;
      const MAX_THREADS_PER_DIM = 65535 * 8;

      let px = x;
      let py = y;
      let pz = z;

      // we spread if we exceed GPU limits OR if it involves a large 1D dispatch
      const exceedsLimits = x > MAX_THREADS_PER_DIM || y > MAX_THREADS_PER_DIM || z > MAX_THREADS_PER_DIM;
      const isLarge1D = totalIterations > 1024 && y === 1 && z === 1;

      if (exceedsLimits || isLarge1D) {
        // Always use 2D square spreading (√N × √N).
        // Benchmarks showed 2D square equals or outperforms 3D cube at every
        // scale tested, with simpler index reconstruction in the shader.
        px = Math.ceil(Math.sqrt(totalIterations));
        py = Math.ceil(totalIterations / px);
        pz = 1;
      }

      shader.setUniform('uPhysicalCount', [px, py, pz]);

      const workgroupCountX = Math.ceil(px / WORKGROUP_SIZE_X);
      const workgroupCountY = Math.ceil(py / WORKGROUP_SIZE_Y);
      const workgroupCountZ = Math.ceil(pz / WORKGROUP_SIZE_Z);

      const commandEncoder = this.device.createCommandEncoder();
      const passEncoder = commandEncoder.beginComputePass();
      this.setupShaderBindGroups(shader, passEncoder, {
        compute: true,
        workgroupSize: [WORKGROUP_SIZE_X, WORKGROUP_SIZE_Y, WORKGROUP_SIZE_Z],
      });

      // Dispatch compute workgroups
      passEncoder.dispatchWorkgroups(workgroupCountX, workgroupCountY, workgroupCountZ);

      passEncoder.end();
      this.device.queue.submit([commandEncoder.finish()]);
    }
  }

  p5.RendererWebGPU = RendererWebGPU;

  p5.renderers[constants.WEBGPU] = p5.RendererWebGPU;

  // TODO: move this and the duplicate in the WebGL renderer to another file
  fn.setAttributes = async function (key, value) {
    return this._renderer._setAttributes(key, value);
  }

}

export default rendererWebGPU;

if (typeof p5 !== "undefined") {
  rendererWebGPU(p5, p5.prototype);
}
