/* Copyright (c) 2022, NVIDIA CORPORATION. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *  * Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *  * Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *  * Neither the name of NVIDIA CORPORATION nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "render_particles.h"

#define HELPERGL_EXTERN_GL_FUNC_IMPLEMENTATION

// includes for OpenGL
#include <helper_gl.h>

// includes
#include <assert.h>
#include <cuda_gl_interop.h>
#include <cuda_runtime.h>
#include <helper_cuda.h>
#include <math.h>

#define GL_POINT_SPRITE_ARB             0x8861
#define GL_COORD_REPLACE_ARB            0x8862
#define GL_VERTEX_PROGRAM_POINT_SIZE_NV 0x8642

ParticleRenderer::ParticleRenderer()
    : m_pos(0)
    , m_numParticles(0)
    , m_pointSize(1.0f)
    , m_spriteSize(2.0f)
    , m_vertexShader(0)
    , m_vertexShaderPoints(0)
    , m_pixelShader(0)
    , m_programPoints(0)
    , m_programSprites(0)
    , m_texture(0)
    , m_pbo(0)
    , m_vboColor(0)
    , m_bFp64Positions(false)
{
    _initGL();
}

ParticleRenderer::~ParticleRenderer() { m_pos = 0; }

void ParticleRenderer::resetPBO() { glDeleteBuffers(1, (GLuint *)&m_pbo); }

void ParticleRenderer::setPositions(float *pos, int numParticles)
{
    m_pos          = pos;
    m_numParticles = numParticles;

    if (!m_pbo) {
        glGenBuffers(1, (GLuint *)&m_pbo);
    }

    glBindBuffer(GL_ARRAY_BUFFER, m_pbo);
    glBufferData(GL_ARRAY_BUFFER, numParticles * 4 * sizeof(float), pos, GL_STATIC_DRAW);
    glBindBuffer(GL_ARRAY_BUFFER, 0);
    SDK_CHECK_ERROR_GL();
}

void ParticleRenderer::setPositions(double *pos, int numParticles)
{
    m_bFp64Positions = true;
    m_pos_fp64       = pos;
    m_numParticles   = numParticles;

    if (!m_pbo) {
        glGenBuffers(1, (GLuint *)&m_pbo);
    }

    glBindBuffer(GL_ARRAY_BUFFER, m_pbo);
    glBufferData(GL_ARRAY_BUFFER, numParticles * 4 * sizeof(double), pos, GL_STATIC_DRAW);
    glBindBuffer(GL_ARRAY_BUFFER, 0);
    SDK_CHECK_ERROR_GL();
}

void ParticleRenderer::setColors(float *color, int numParticles)
{
    glBindBuffer(GL_ARRAY_BUFFER, m_vboColor);
    glBufferData(GL_ARRAY_BUFFER, numParticles * 4 * sizeof(float), color, GL_STATIC_DRAW);
    glBindBuffer(GL_ARRAY_BUFFER, 0);
}

void ParticleRenderer::setBaseColor(float color[4])
{
    for (int i = 0; i < 4; i++)
        m_baseColor[i] = color[i];
}

void ParticleRenderer::setPBO(unsigned int pbo, int numParticles, bool fp64)
{
    m_pbo          = pbo;
    m_numParticles = numParticles;

    if (fp64)
        m_bFp64Positions = true;
}

void ParticleRenderer::_drawPoints(bool color)
{
    if (!m_pbo) {
        glBegin(GL_POINTS);
        {
            int k = 0;

            for (int i = 0; i < m_numParticles; ++i) {
                if (m_bFp64Positions)
                    glVertex3dv(&m_pos_fp64[k]);
                else {
                    glVertex3fv(&m_pos[k]);
                }

                k += 4;
            }
        }
        glEnd();
    }
    else {
        glEnableClientState(GL_VERTEX_ARRAY);

        glBindBuffer(GL_ARRAY_BUFFER, m_pbo);

        if (m_bFp64Positions)
            glVertexPointer(4, GL_DOUBLE, 0, 0);
        else
            glVertexPointer(4, GL_FLOAT, 0, 0);

        if (color) {
            glEnableClientState(GL_COLOR_ARRAY);
            glBindBuffer(GL_ARRAY_BUFFER, m_vboColor);
            // glActiveTexture(GL_TEXTURE1);
            // glTexCoordPointer(4, GL_FLOAT, 0, 0);
            glColorPointer(4, GL_FLOAT, 0, 0);
        }

        glDrawArrays(GL_POINTS, 0, m_numParticles);
        glBindBuffer(GL_ARRAY_BUFFER, 0);
        glDisableClientState(GL_VERTEX_ARRAY);
        glDisableClientState(GL_COLOR_ARRAY);
    }
}

void ParticleRenderer::display(DisplayMode mode /* = PARTICLE_POINTS */)
{
    switch (mode) {
    case PARTICLE_POINTS:
        glColor3f(1, 1, 1);
        glPointSize(m_pointSize);
        glUseProgram(m_programPoints);
        _drawPoints();
        glUseProgram(0);
        break;

    case PARTICLE_SPRITES:
    default: {
        // setup point sprites
        glEnable(GL_POINT_SPRITE_ARB);
        glTexEnvi(GL_POINT_SPRITE_ARB, GL_COORD_REPLACE_ARB, GL_TRUE);
        glEnable(GL_VERTEX_PROGRAM_POINT_SIZE_NV);
        glPointSize(m_spriteSize);
        glBlendFunc(GL_SRC_ALPHA, GL_ONE);
        glEnable(GL_BLEND);
        glDepthMask(GL_FALSE);

        glUseProgram(m_programSprites);
        GLuint texLoc = glGetUniformLocation(m_programSprites, "splatTexture");
        glUniform1i(texLoc, 0);

        glActiveTexture(GL_TEXTURE0);
        glBindTexture(GL_TEXTURE_2D, m_texture);

        glColor3f(1, 1, 1);
        glSecondaryColor3fv(m_baseColor);

        _drawPoints();

        glUseProgram(0);

        glDisable(GL_POINT_SPRITE_ARB);
        glDisable(GL_BLEND);
        glDepthMask(GL_TRUE);
    }

    break;

    case PARTICLE_SPRITES_COLOR: {
        // setup point sprites
        glEnable(GL_POINT_SPRITE_ARB);
        glTexEnvi(GL_POINT_SPRITE_ARB, GL_COORD_REPLACE_ARB, GL_TRUE);
        glEnable(GL_VERTEX_PROGRAM_POINT_SIZE_NV);
        glPointSize(m_spriteSize);
        glBlendFunc(GL_SRC_ALPHA, GL_ONE);
        glEnable(GL_BLEND);
        glDepthMask(GL_FALSE);

        glUseProgram(m_programSprites);
        GLuint texLoc = glGetUniformLocation(m_programSprites, "splatTexture");
        glUniform1i(texLoc, 0);

        glActiveTexture(GL_TEXTURE0);
        glBindTexture(GL_TEXTURE_2D, m_texture);

        glColor3f(1, 1, 1);
        glSecondaryColor3fv(m_baseColor);

        _drawPoints(true);

        glUseProgram(0);

        glDisable(GL_POINT_SPRITE_ARB);
        glDisable(GL_BLEND);
        glDepthMask(GL_TRUE);
    }

    break;
    }

    SDK_CHECK_ERROR_GL();
}

const char vertexShaderPoints[] = {"void main()                                                            \n"
                                   "{                                                                      \n"
                                   "    vec4 vert = vec4(gl_Vertex.xyz, 1.0);  			       "
                                   " "
                                   "              \n"
                                   "    gl_Position = gl_ProjectionMatrix * gl_ModelViewMatrix * vert;        "
                                   "                   \n"
                                   "    gl_FrontColor = gl_Color;                                          \n"
                                   "}                                                                      "
                                   "\n"};

const char vertexShader[] = {"void main()                                                            \n"
                             "{                                                                      \n"
                             "    float pointSize = 500.0 * gl_Point.size;                           \n"
                             "    vec4 vert = gl_Vertex;						"
                             "						\n"
                             "    vert.w = 1.0;							"
                             "	"
                             "						\n"
                             "    vec3 pos_eye = vec3 (gl_ModelViewMatrix * vert);                   \n"
                             "    gl_PointSize = max(1.0, pointSize / (1.0 - pos_eye.z));            \n"
                             "    gl_TexCoord[0] = gl_MultiTexCoord0;                                \n"
                             //"    gl_TexCoord[1] = gl_MultiTexCoord1; \n"
                             "    gl_Position = gl_ProjectionMatrix * gl_ModelViewMatrix * vert;     \n"
                             "    gl_FrontColor = gl_Color;                                          \n"
                             "    gl_FrontSecondaryColor = gl_SecondaryColor;                        \n"
                             "}                                                                      "
                             "\n"};

const char pixelShader[] = {"uniform sampler2D splatTexture;                                        \n"

                            "void main()                                                            \n"
                            "{                                                                      \n"
                            "    vec4 color2 = gl_SecondaryColor;                                   \n"
                            "    vec4 color = (0.6 + 0.4 * gl_Color) * texture2D(splatTexture, "
                            "gl_TexCoord[0].st); \n"
                            "    gl_FragColor =                                                     \n"
                            "         color * color2;\n" // mix(vec4(0.1, 0.0, 0.0, color.w), color2,
                                                         // color.w);\n"
                            "}                                                                      "
                            "\n"};

void ParticleRenderer::_initGL()
{
    m_vertexShader       = glCreateShader(GL_VERTEX_SHADER);
    m_vertexShaderPoints = glCreateShader(GL_VERTEX_SHADER);
    m_pixelShader        = glCreateShader(GL_FRAGMENT_SHADER);

    const char *v = vertexShader;
    const char *p = pixelShader;
    glShaderSource(m_vertexShader, 1, &v, 0);
    glShaderSource(m_pixelShader, 1, &p, 0);
    const char *vp = vertexShaderPoints;
    glShaderSource(m_vertexShaderPoints, 1, &vp, 0);

    glCompileShader(m_vertexShader);
    glCompileShader(m_vertexShaderPoints);
    glCompileShader(m_pixelShader);

    m_programSprites = glCreateProgram();
    glAttachShader(m_programSprites, m_vertexShader);
    glAttachShader(m_programSprites, m_pixelShader);
    glLinkProgram(m_programSprites);

    m_programPoints = glCreateProgram();
    glAttachShader(m_programPoints, m_vertexShaderPoints);
    glLinkProgram(m_programPoints);

    _createTexture(32);

    glGenBuffers(1, (GLuint *)&m_vboColor);
    glBindBuffer(GL_ARRAY_BUFFER, m_vboColor);
    glBufferData(GL_ARRAY_BUFFER, m_numParticles * 4 * sizeof(float), 0, GL_STATIC_DRAW);
    glBindBuffer(GL_ARRAY_BUFFER, 0);
}

//------------------------------------------------------------------------------
// Function           : EvalHermite
// Description      :
//------------------------------------------------------------------------------
/**
 * EvalHermite(float pA, float pB, float vA, float vB, float u)
 * @brief Evaluates Hermite basis functions for the specified coefficients.
 */
inline float evalHermite(float pA, float pB, float vA, float vB, float u)
{
    float u2 = (u * u), u3 = u2 * u;
    float B0 = 2 * u3 - 3 * u2 + 1;
    float B1 = -2 * u3 + 3 * u2;
    float B2 = u3 - 2 * u2 + u;
    float B3 = u3 - u;
    return (B0 * pA + B1 * pB + B2 * vA + B3 * vB);
}

unsigned char *createGaussianMap(int N)
{
    float         *M = new float[2 * N * N];
    unsigned char *B = new unsigned char[4 * N * N];
    float          X, Y, Y2, Dist;
    float          Incr = 2.0f / N;
    int            i    = 0;
    int            j    = 0;
    Y                   = -1.0f;

    // float mmax = 0;
    for (int y = 0; y < N; y++, Y += Incr) {
        Y2 = Y * Y;
        X  = -1.0f;

        for (int x = 0; x < N; x++, X += Incr, i += 2, j += 4) {
            Dist = (float)sqrtf(X * X + Y2);

            if (Dist > 1)
                Dist = 1;

            M[i + 1] = M[i] = evalHermite(1.0f, 0, 0, 0, Dist);
            B[j + 3] = B[j + 2] = B[j + 1] = B[j] = (unsigned char)(M[i] * 255);
        }
    }

    delete[] M;
    return (B);
}

void ParticleRenderer::_createTexture(int resolution)
{
    unsigned char *data = createGaussianMap(resolution);
    glGenTextures(1, (GLuint *)&m_texture);
    glBindTexture(GL_TEXTURE_2D, m_texture);
    glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP_SGIS, GL_TRUE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, resolution, resolution, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
}
