//This is pretty stand-alone code to dump the current OpenGL buffer to a PPM.
//You need to provide proper width and height of the image you want
//to capture. (Here its just been set to 480x480).

void monitor::windowDump(void){
  int i,j;
  FILE *fptr;
  static int counter = 0; //this supports animation sequences
  char fname[32];
  unsigned char *image;
  int width=480, height=480, stereo=0;

  //Allocate our buffer for the image
  image = (unsigned char *) malloc(3*width*height*sizeof(char));
  if (image == NULL){
    fprintf(stderr,"Failed to allocate memory for image\n");
    return;
  }

  glPixelStorei(GL_PACK_ALIGNMENT,1);

  //Open the file
  if (stereo)
    sprintf(fname,"L_%04d.raw",counter);
  else
    sprintf(fname,"C_%04d.ppm",counter);
  if ((fptr = fopen(fname,"w")) == NULL) {
    fprintf(stderr,"Failed to open file for window dump\n");
    return;
  }

  // Copy the image into our buffer
  glReadBuffer(GL_BACK_RIGHT);
  glReadPixels(0,0,width,height,GL_RGB,GL_UNSIGNED_BYTE,image);

  //Write the raw file
  fprintf(fptr,"P6\n%d %d\n255\n",width,height);
  for (j=height-1;j>=0;j--) {
    for (i=0;i<width;i++) {
      fputc(image[3*j*width+3*i+0],fptr);
      fputc(image[3*j*width+3*i+1],fptr);
      fputc(image[3*j*width+3*i+2],fptr);
    }
  }
  fclose(fptr);


  // Clean up
  counter++;
  free(image);
  return;
}