cuda-samples/Samples/0_Introduction/simpleCUDA2GL/main.cpp

/* 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.
 */

// USE_TEXSUBIMAGE2D uses glTexSubImage2D() to update the final result
// commenting it will make the sample use the other way :
// map a texture in CUDA and blit the result into it
#define USE_TEXSUBIMAGE2D

#if defined(WIN32) || defined(_WIN32) || defined(WIN64) || defined(_WIN64)
#define WINDOWS_LEAN_AND_MEAN
#define NOMINMAX
#include <windows.h>
#pragma warning(disable : 4996)
#endif

// OpenGL Graphics includes
#include <helper_gl.h>
#if defined(__APPLE__) || defined(MACOSX)
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
#include <GLUT/glut.h>
// Sorry for Apple : unsigned int sampler is not available to you, yet...
// Let's switch to the use of PBO and glTexSubImage
#define USE_TEXSUBIMAGE2D
#else
#include <GL/freeglut.h>
#endif

// CUDA includes
#include <cuda_runtime.h>
#include <cuda_gl_interop.h>

// CUDA utilities and system includes
#include <helper_cuda.h>
#include <helper_functions.h>
#include <rendercheck_gl.h>

// Shared Library Test Functions
#define MAX_EPSILON 10
#define REFRESH_DELAY 10  // ms

const char *sSDKname = "simpleCUDA2GL";

unsigned int g_TotalErrors = 0;

// CheckFBO/BackBuffer class objects
CheckRender *g_CheckRender = NULL;

////////////////////////////////////////////////////////////////////////////////
// constants / global variables
unsigned int window_width = 512;
unsigned int window_height = 512;
unsigned int image_width = 512;
unsigned int image_height = 512;
int iGLUTWindowHandle = 0;  // handle to the GLUT window

// pbo and fbo variables
#ifdef USE_TEXSUBIMAGE2D
GLuint pbo_dest;
struct cudaGraphicsResource *cuda_pbo_dest_resource;
#else
unsigned int *cuda_dest_resource;
GLuint shDrawTex;  // draws a texture
struct cudaGraphicsResource *cuda_tex_result_resource;
#endif

GLuint fbo_source;
struct cudaGraphicsResource *cuda_tex_screen_resource;

unsigned int size_tex_data;
unsigned int num_texels;
unsigned int num_values;

// (offscreen) render target fbo variables
GLuint tex_screen;      // where we render the image
GLuint tex_cudaResult;  // where we will copy the CUDA result

char *ref_file = NULL;
bool enable_cuda = true;

int *pArgc = NULL;
char **pArgv = NULL;

// Timer
static int fpsCount = 0;
static int fpsLimit = 1;
StopWatchInterface *timer = NULL;

#ifndef USE_TEXTURE_RGBA8UI
#pragma message("Note: Using Texture fmt GL_RGBA16F_ARB")
#else
// NOTE: the current issue with regular RGBA8 internal format of textures
// is that HW stores them as BGRA8. Therefore CUDA will see BGRA where users
// expected RGBA8. To prevent this issue, the driver team decided to prevent
// this to happen
// instead, use RGBA8UI which required the additional work of scaling the
// fragment shader
// output from 0-1 to 0-255. This is why we have some GLSL code, in this case
#pragma message("Note: Using Texture RGBA8UI + GLSL for rendering")
#endif
GLuint shDraw;

////////////////////////////////////////////////////////////////////////////////
extern "C" void launch_cudaProcess(dim3 grid, dim3 block, int sbytes,
                                   unsigned int *g_odata, int imgw);

// Forward declarations
void runStdProgram(int argc, char **argv);
void FreeResource();
void Cleanup(int iExitCode);

// GL functionality
bool initGL(int *argc, char **argv);

#ifdef USE_TEXSUBIMAGE2D
void createPBO(GLuint *pbo, struct cudaGraphicsResource **pbo_resource);
void deletePBO(GLuint *pbo);
#endif

void createTextureDst(GLuint *tex_cudaResult, unsigned int size_x,
                      unsigned int size_y);
void deleteTexture(GLuint *tex);

// rendering callbacks
void display();
void idle();
void keyboard(unsigned char key, int x, int y);
void reshape(int w, int h);
void mainMenu(int i);

#ifdef USE_TEXSUBIMAGE2D
////////////////////////////////////////////////////////////////////////////////
//! Create PBO
////////////////////////////////////////////////////////////////////////////////
void createPBO(GLuint *pbo, struct cudaGraphicsResource **pbo_resource) {
  // set up vertex data parameter
  num_texels = image_width * image_height;
  num_values = num_texels * 4;
  size_tex_data = sizeof(GLubyte) * num_values;
  void *data = malloc(size_tex_data);

  // create buffer object
  glGenBuffers(1, pbo);
  glBindBuffer(GL_ARRAY_BUFFER, *pbo);
  glBufferData(GL_ARRAY_BUFFER, size_tex_data, data, GL_DYNAMIC_DRAW);
  free(data);

  glBindBuffer(GL_ARRAY_BUFFER, 0);

  // register this buffer object with CUDA
  checkCudaErrors(cudaGraphicsGLRegisterBuffer(pbo_resource, *pbo,
                                               cudaGraphicsMapFlagsNone));

  SDK_CHECK_ERROR_GL();
}

void deletePBO(GLuint *pbo) {
  glDeleteBuffers(1, pbo);
  SDK_CHECK_ERROR_GL();
  *pbo = 0;
}
#endif

const GLenum fbo_targets[] = {
    GL_COLOR_ATTACHMENT0_EXT, GL_COLOR_ATTACHMENT1_EXT,
    GL_COLOR_ATTACHMENT2_EXT, GL_COLOR_ATTACHMENT3_EXT};

#ifndef USE_TEXSUBIMAGE2D
static const char *glsl_drawtex_vertshader_src =
    "void main(void)\n"
    "{\n"
    "	gl_Position = gl_Vertex;\n"
    "	gl_TexCoord[0].xy = gl_MultiTexCoord0.xy;\n"
    "}\n";

static const char *glsl_drawtex_fragshader_src =
    "#version 130\n"
    "uniform usampler2D texImage;\n"
    "void main()\n"
    "{\n"
    "   vec4 c = texture(texImage, gl_TexCoord[0].xy);\n"
    "	gl_FragColor = c / 255.0;\n"
    "}\n";
#endif

static const char *glsl_draw_fragshader_src =
// WARNING: seems like the gl_FragColor doesn't want to output >1 colors...
// you need version 1.3 so you can define a uvec4 output...
// but MacOSX complains about not supporting 1.3 !!
// for now, the mode where we use RGBA8UI may not work properly for Apple : only
// RGBA16F works (default)
#if defined(__APPLE__) || defined(MACOSX)
    "void main()\n"
    "{"
    "  gl_FragColor = vec4(gl_Color * 255.0);\n"
    "}\n";
#else
    "#version 130\n"
    "out uvec4 FragColor;\n"
    "void main()\n"
    "{"
    "  FragColor = uvec4(gl_Color.xyz * 255.0, 255.0);\n"
    "}\n";
#endif

// copy image and process using CUDA
void generateCUDAImage() {
  // run the Cuda kernel
  unsigned int *out_data;

#ifdef USE_TEXSUBIMAGE2D
  checkCudaErrors(cudaGraphicsMapResources(1, &cuda_pbo_dest_resource, 0));
  size_t num_bytes;
  checkCudaErrors(cudaGraphicsResourceGetMappedPointer(
      (void **)&out_data, &num_bytes, cuda_pbo_dest_resource));
// printf("CUDA mapped pointer of pbo_out: May access %ld bytes, expected %d\n",
// num_bytes, size_tex_data);
#else
  out_data = cuda_dest_resource;
#endif
  // calculate grid size
  dim3 block(16, 16, 1);
  // dim3 block(16, 16, 1);
  dim3 grid(image_width / block.x, image_height / block.y, 1);
  // execute CUDA kernel
  launch_cudaProcess(grid, block, 0, out_data, image_width);

// CUDA generated data in cuda memory or in a mapped PBO made of BGRA 8 bits
// 2 solutions, here :
// - use glTexSubImage2D(), there is the potential to loose performance in
// possible hidden conversion
// - map the texture and blit the result thanks to CUDA API
#ifdef USE_TEXSUBIMAGE2D
  checkCudaErrors(cudaGraphicsUnmapResources(1, &cuda_pbo_dest_resource, 0));
  glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, pbo_dest);

  glBindTexture(GL_TEXTURE_2D, tex_cudaResult);
  glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, image_width, image_height, GL_RGBA,
                  GL_UNSIGNED_BYTE, NULL);
  SDK_CHECK_ERROR_GL();
  glBindBuffer(GL_PIXEL_PACK_BUFFER_ARB, 0);
  glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, 0);
#else
  // We want to copy cuda_dest_resource data to the texture
  // map buffer objects to get CUDA device pointers
  cudaArray *texture_ptr;
  checkCudaErrors(cudaGraphicsMapResources(1, &cuda_tex_result_resource, 0));
  checkCudaErrors(cudaGraphicsSubResourceGetMappedArray(
      &texture_ptr, cuda_tex_result_resource, 0, 0));

  int num_texels = image_width * image_height;
  int num_values = num_texels * 4;
  int size_tex_data = sizeof(GLubyte) * num_values;
  checkCudaErrors(cudaMemcpyToArray(texture_ptr, 0, 0, cuda_dest_resource,
                                    size_tex_data, cudaMemcpyDeviceToDevice));

  checkCudaErrors(cudaGraphicsUnmapResources(1, &cuda_tex_result_resource, 0));
#endif
}

// display image to the screen as textured quad
void displayImage(GLuint texture) {
  glBindTexture(GL_TEXTURE_2D, texture);
  glEnable(GL_TEXTURE_2D);
  glDisable(GL_DEPTH_TEST);
  glDisable(GL_LIGHTING);
  glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);

  glMatrixMode(GL_PROJECTION);
  glPushMatrix();
  glLoadIdentity();
  glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);

  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();

  glViewport(0, 0, window_width, window_height);

// if the texture is a 8 bits UI, scale the fetch with a GLSL shader
#ifndef USE_TEXSUBIMAGE2D
  glUseProgram(shDrawTex);
  GLint id = glGetUniformLocation(shDrawTex, "texImage");
  glUniform1i(id, 0);  // texture unit 0 to "texImage"
  SDK_CHECK_ERROR_GL();
#endif

  glBegin(GL_QUADS);
  glTexCoord2f(0.0, 0.0);
  glVertex3f(-1.0, -1.0, 0.5);
  glTexCoord2f(1.0, 0.0);
  glVertex3f(1.0, -1.0, 0.5);
  glTexCoord2f(1.0, 1.0);
  glVertex3f(1.0, 1.0, 0.5);
  glTexCoord2f(0.0, 1.0);
  glVertex3f(-1.0, 1.0, 0.5);
  glEnd();

  glMatrixMode(GL_PROJECTION);
  glPopMatrix();

  glDisable(GL_TEXTURE_2D);

#ifndef USE_TEXSUBIMAGE2D
  glUseProgram(0);
#endif
  SDK_CHECK_ERROR_GL();
}

////////////////////////////////////////////////////////////////////////////////
//! Display callback
////////////////////////////////////////////////////////////////////////////////
void display() {
  sdkStartTimer(&timer);

  if (enable_cuda) {
    generateCUDAImage();
    displayImage(tex_cudaResult);
  }

  // NOTE: I needed to add this call so the timing is consistent.
  // Need to investigate why
  cudaDeviceSynchronize();
  sdkStopTimer(&timer);

  // flip backbuffer
  glutSwapBuffers();

  // If specified, Check rendering against reference,
  if (ref_file && g_CheckRender && g_CheckRender->IsQAReadback()) {
    static int pass = 0;

    if (pass > 0) {
      g_CheckRender->readback(window_width, window_height);
      char currentOutputPPM[256];
      sprintf(currentOutputPPM, "kilt.ppm");
      g_CheckRender->savePPM(currentOutputPPM, true, NULL);

      if (!g_CheckRender->PPMvsPPM(currentOutputPPM,
                                   sdkFindFilePath(ref_file, pArgv[0]),
                                   MAX_EPSILON, 0.30f)) {
        g_TotalErrors++;
      }

      Cleanup((g_TotalErrors == 0) ? EXIT_SUCCESS : EXIT_FAILURE);
    }

    pass++;
  }

  // Update fps counter, fps/title display and log
  if (++fpsCount == fpsLimit) {
    char cTitle[256];
    float fps = 1000.0f / sdkGetAverageTimerValue(&timer);
    sprintf(cTitle, "CUDA GL Post Processing (%d x %d): %.1f fps", window_width,
            window_height, fps);
    glutSetWindowTitle(cTitle);
    // printf("%s\n", cTitle);
    fpsCount = 0;
    fpsLimit = (int)((fps > 1.0f) ? fps : 1.0f);
    sdkResetTimer(&timer);
  }
}

void timerEvent(int value) {
  glutPostRedisplay();
  glutTimerFunc(REFRESH_DELAY, timerEvent, 0);
}

////////////////////////////////////////////////////////////////////////////////
//! Keyboard events handler
////////////////////////////////////////////////////////////////////////////////
void keyboard(unsigned char key, int /*x*/, int /*y*/) {
  switch (key) {
    case (27):
      Cleanup(EXIT_SUCCESS);
      break;

    case ' ':
      enable_cuda ^= 1;
#ifdef USE_TEXTURE_RGBA8UI

      if (enable_cuda) {
        glClearColorIuiEXT(128, 128, 128, 255);
      } else {
        glClearColor(0.5, 0.5, 0.5, 1.0);
      }

#endif
      break;
  }
}

void reshape(int w, int h) {
  window_width = w;
  window_height = h;
}

void mainMenu(int i) { keyboard((unsigned char)i, 0, 0); }

////////////////////////////////////////////////////////////////////////////////
//!
////////////////////////////////////////////////////////////////////////////////
void createTextureDst(GLuint *tex_cudaResult, unsigned int size_x,
                      unsigned int size_y) {
  // create a texture
  glGenTextures(1, tex_cudaResult);
  glBindTexture(GL_TEXTURE_2D, *tex_cudaResult);

  // set basic parameters
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

#ifdef USE_TEXSUBIMAGE2D
  glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, size_x, size_y, 0, GL_RGBA,
               GL_UNSIGNED_BYTE, NULL);
  SDK_CHECK_ERROR_GL();
#else
  glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8UI_EXT, size_x, size_y, 0,
               GL_RGBA_INTEGER_EXT, GL_UNSIGNED_BYTE, NULL);
  SDK_CHECK_ERROR_GL();
  // register this texture with CUDA
  checkCudaErrors(cudaGraphicsGLRegisterImage(
      &cuda_tex_result_resource, *tex_cudaResult, GL_TEXTURE_2D,
      cudaGraphicsMapFlagsWriteDiscard));
#endif
}

////////////////////////////////////////////////////////////////////////////////
//!
////////////////////////////////////////////////////////////////////////////////
void deleteTexture(GLuint *tex) {
  glDeleteTextures(1, tex);
  SDK_CHECK_ERROR_GL();

  *tex = 0;
}

////////////////////////////////////////////////////////////////////////////////
// Program main
////////////////////////////////////////////////////////////////////////////////
int main(int argc, char **argv) {
#if defined(__linux__)
  char *Xstatus = getenv("DISPLAY");
  if (Xstatus == NULL) {
    printf("Waiving execution as X server is not running\n");
    exit(EXIT_WAIVED);
  }
  setenv("DISPLAY", ":0", 0);
#endif

  printf("%s Starting...\n\n", argv[0]);

  if (checkCmdLineFlag(argc, (const char **)argv, "file")) {
    getCmdLineArgumentString(argc, (const char **)argv, "file", &ref_file);
  }

  pArgc = &argc;
  pArgv = argv;

  // use command-line specified CUDA device, otherwise use device with highest
  // Gflops/s
  if (checkCmdLineFlag(argc, (const char **)argv, "device")) {
    printf("[%s]\n", argv[0]);
    printf("   Does not explicitly support -device=n\n");
    printf(
        "   This sample requires OpenGL.  Only -file=<reference> are "
        "supported\n");
    printf("exiting...\n");
    exit(EXIT_WAIVED);
  }

  if (ref_file) {
    printf("(Test with OpenGL verification)\n");
    runStdProgram(argc, argv);
  } else {
    printf("(Interactive OpenGL Demo)\n");
    runStdProgram(argc, argv);
  }

  exit(EXIT_SUCCESS);
}

////////////////////////////////////////////////////////////////////////////////
//!
////////////////////////////////////////////////////////////////////////////////
void FreeResource() {
  sdkDeleteTimer(&timer);

// unregister this buffer object with CUDA
//    checkCudaErrors(cudaGraphicsUnregisterResource(cuda_tex_screen_resource));
#ifdef USE_TEXSUBIMAGE2D
  checkCudaErrors(cudaGraphicsUnregisterResource(cuda_pbo_dest_resource));
  deletePBO(&pbo_dest);
#else
  cudaFree(cuda_dest_resource);
#endif
  deleteTexture(&tex_screen);
  deleteTexture(&tex_cudaResult);

  if (iGLUTWindowHandle) {
    glutDestroyWindow(iGLUTWindowHandle);
  }

  // finalize logs and leave
  printf("simpleCUDA2GL Exiting...\n");
}

void Cleanup(int iExitCode) {
  FreeResource();
  printf("PPM Images are %s\n",
         (iExitCode == EXIT_SUCCESS) ? "Matching" : "Not Matching");
  exit(iExitCode);
}

////////////////////////////////////////////////////////////////////////////////
//!
////////////////////////////////////////////////////////////////////////////////
GLuint compileGLSLprogram(const char *vertex_shader_src,
                          const char *fragment_shader_src) {
  GLuint v, f, p = 0;

  p = glCreateProgram();

  if (vertex_shader_src) {
    v = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(v, 1, &vertex_shader_src, NULL);
    glCompileShader(v);

    // check if shader compiled
    GLint compiled = 0;
    glGetShaderiv(v, GL_COMPILE_STATUS, &compiled);

    if (!compiled) {
      //#ifdef NV_REPORT_COMPILE_ERRORS
      char temp[256] = "";
      glGetShaderInfoLog(v, 256, NULL, temp);
      printf("Vtx Compile failed:\n%s\n", temp);
      //#endif
      glDeleteShader(v);
      return 0;
    } else {
      glAttachShader(p, v);
    }
  }

  if (fragment_shader_src) {
    f = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(f, 1, &fragment_shader_src, NULL);
    glCompileShader(f);

    // check if shader compiled
    GLint compiled = 0;
    glGetShaderiv(f, GL_COMPILE_STATUS, &compiled);

    if (!compiled) {
      //#ifdef NV_REPORT_COMPILE_ERRORS
      char temp[256] = "";
      glGetShaderInfoLog(f, 256, NULL, temp);
      printf("frag Compile failed:\n%s\n", temp);
      //#endif
      glDeleteShader(f);
      return 0;
    } else {
      glAttachShader(p, f);
    }
  }

  glLinkProgram(p);

  int infologLength = 0;
  int charsWritten = 0;

  glGetProgramiv(p, GL_INFO_LOG_LENGTH, (GLint *)&infologLength);

  if (infologLength > 0) {
    char *infoLog = (char *)malloc(infologLength);
    glGetProgramInfoLog(p, infologLength, (GLsizei *)&charsWritten, infoLog);
    printf("Shader compilation error: %s\n", infoLog);
    free(infoLog);
  }

  return p;
}

////////////////////////////////////////////////////////////////////////////////
//! Allocate the "render target" of CUDA
////////////////////////////////////////////////////////////////////////////////
#ifndef USE_TEXSUBIMAGE2D
void initCUDABuffers() {
  // set up vertex data parameter
  num_texels = image_width * image_height;
  num_values = num_texels * 4;
  size_tex_data = sizeof(GLubyte) * num_values;
  checkCudaErrors(cudaMalloc((void **)&cuda_dest_resource, size_tex_data));
  // checkCudaErrors(cudaHostAlloc((void**)&cuda_dest_resource, size_tex_data,
  // ));
}
#endif

////////////////////////////////////////////////////////////////////////////////
//!
////////////////////////////////////////////////////////////////////////////////
void initGLBuffers() {
// create pbo
#ifdef USE_TEXSUBIMAGE2D
  createPBO(&pbo_dest, &cuda_pbo_dest_resource);
#endif
  // create texture that will receive the result of CUDA
  createTextureDst(&tex_cudaResult, image_width, image_height);
  // load shader programs
  shDraw = compileGLSLprogram(NULL, glsl_draw_fragshader_src);

#ifndef USE_TEXSUBIMAGE2D
  shDrawTex = compileGLSLprogram(glsl_drawtex_vertshader_src,
                                 glsl_drawtex_fragshader_src);
#endif
  SDK_CHECK_ERROR_GL();
}

////////////////////////////////////////////////////////////////////////////////
//! Run standard demo loop with or without GL verification
////////////////////////////////////////////////////////////////////////////////
void runStdProgram(int argc, char **argv) {
  // First initialize OpenGL context, so we can properly set the GL for CUDA.
  // This is necessary in order to achieve optimal performance with OpenGL/CUDA
  // interop.
  if (false == initGL(&argc, argv)) {
    return;
  }

  // Now initialize CUDA context (GL context has been created already)
  findCudaDevice(argc, (const char **)argv);

  sdkCreateTimer(&timer);
  sdkResetTimer(&timer);

  // register callbacks
  glutDisplayFunc(display);
  glutKeyboardFunc(keyboard);
  glutReshapeFunc(reshape);
  glutTimerFunc(REFRESH_DELAY, timerEvent, 0);

  // create menu
  glutCreateMenu(mainMenu);
  glutAddMenuEntry("Quit (esc)", '\033');
  glutAttachMenu(GLUT_RIGHT_BUTTON);

  initGLBuffers();
#ifndef USE_TEXSUBIMAGE2D
  initCUDABuffers();
#endif

  // Creating the Auto-Validation Code
  if (ref_file) {
    g_CheckRender = new CheckBackBuffer(window_width, window_height, 4);
    g_CheckRender->setPixelFormat(GL_RGBA);
    g_CheckRender->setExecPath(argv[0]);
    g_CheckRender->EnableQAReadback(true);
  }

  printf(
      "\n"
      "\tControls\n"
      "\t(right click mouse button for Menu)\n"
      "\t[esc] - Quit\n\n");

  // start rendering mainloop
  glutMainLoop();

  // Normally unused return path
  Cleanup(EXIT_SUCCESS);
}

////////////////////////////////////////////////////////////////////////////////
//! Initialize GL
////////////////////////////////////////////////////////////////////////////////
bool initGL(int *argc, char **argv) {
  // Create GL context
  glutInit(argc, argv);
  glutInitDisplayMode(GLUT_RGBA | GLUT_ALPHA | GLUT_DOUBLE | GLUT_DEPTH);
  glutInitWindowSize(window_width, window_height);
  iGLUTWindowHandle = glutCreateWindow("CUDA OpenGL post-processing");

  // initialize necessary OpenGL extensions
  if (!isGLVersionSupported(2, 0) ||
      !areGLExtensionsSupported("GL_ARB_pixel_buffer_object "
                                "GL_EXT_framebuffer_object")) {
    printf("ERROR: Support for necessary OpenGL extensions missing.");
    fflush(stderr);
    return false;
  }

// default initialization
#ifndef USE_TEXTURE_RGBA8UI
  glClearColor(0.5, 0.5, 0.5, 1.0);
#else
  glClearColorIuiEXT(128, 128, 128, 255);
#endif
  glDisable(GL_DEPTH_TEST);

  // viewport
  glViewport(0, 0, window_width, window_height);

  // projection
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  gluPerspective(60.0, (GLfloat)window_width / (GLfloat)window_height, 0.1f,
                 10.0f);

  glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);

  glEnable(GL_LIGHT0);
  float red[] = {1.0f, 0.1f, 0.1f, 1.0f};
  float white[] = {1.0f, 1.0f, 1.0f, 1.0f};
  glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, red);
  glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, white);
  glMaterialf(GL_FRONT_AND_BACK, GL_SHININESS, 60.0f);

  SDK_CHECK_ERROR_GL();

  return true;
}