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 * Redistribution and use in source and binary forms, with or without
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 *  * 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,
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define PI 3.1415926536f

/*
 * Paint a 2D texture with a moving red/green hatch pattern on a
 * strobing blue background.  Note that this kernel reads to and
 * writes from the texture, hence why this texture was not mapped
 * as WriteDiscard.
 */
__global__ void cuda_kernel_texture_2d(unsigned char *surface, int width, int height, size_t pitch, float t)
{
    int    x = blockIdx.x * blockDim.x + threadIdx.x;
    int    y = blockIdx.y * blockDim.y + threadIdx.y;
    float *pixel;

    // in the case where, due to quantization into grids, we have
    // more threads than pixels, skip the threads which don't
    // correspond to valid pixels
    if (x >= width || y >= height)
        return;

    // get a pointer to the pixel at (x,y)
    pixel = (float *)(surface + y * pitch) + 4 * x;

    // populate it
    float value_x = 0.5f + 0.5f * cos(t + 10.0f * ((2.0f * x) / width - 1.0f));
    float value_y = 0.5f + 0.5f * cos(t + 10.0f * ((2.0f * y) / height - 1.0f));
    pixel[0]      = 0.5 * pixel[0] + 0.5 * pow(value_x, 3.0f); // red
    pixel[1]      = 0.5 * pixel[1] + 0.5 * pow(value_y, 3.0f); // green
    pixel[2]      = 0.5f + 0.5f * cos(t);                      // blue
    pixel[3]      = 1;                                         // alpha
}

extern "C" void cuda_texture_2d(void *surface, int width, int height, size_t pitch, float t)
{
    cudaError_t error = cudaSuccess;

    dim3 Db = dim3(16, 16); // block dimensions are fixed to be 256 threads
    dim3 Dg = dim3((width + Db.x - 1) / Db.x, (height + Db.y - 1) / Db.y);

    cuda_kernel_texture_2d<<<Dg, Db>>>((unsigned char *)surface, width, height, pitch, t);

    error = cudaGetLastError();

    if (error != cudaSuccess) {
        printf("cuda_kernel_texture_2d() failed to launch error = %d\n", error);
    }
}
