/* global definitions for constants and global image arrays */

#define ImageWidth  64
#define ImageHeight 64
GLubyte Image[ImageHeight][ImageWidth][4];

#define	stripeImageWidth 32
GLubyte stripeImage[4*stripeImageWidth];

/*************************************************************
void image_set_up(void):
  generate checkerboard and stripe images. 

* Inside init(), call this function and set up texture objects
  for texture mapping.
  (init() is called from main() before calling glutMainLoop().)
***************************************************************/
void image_set_up(void)
{
 int i, j, c; 
 
 /* --- Generate checkerboard image to the image array ---*/
  for (i = 0; i < ImageHeight; i++)
    for (j = 0; j < ImageWidth; j++)
      {
       c = (((i & 0x8) == 0) ^ ((j & 0x8) == 0));

       if (c == 1) /* white */
	{
         c = 255;  
	 Image[i][j][0] = (GLubyte) c;
         Image[i][j][1] = (GLubyte) c;
         Image[i][j][2] = (GLubyte) c;
	}
       else  /* green */
	{
         Image[i][j][0] = (GLubyte) 0;
         Image[i][j][1] = (GLubyte) 150;
         Image[i][j][2] = (GLubyte) 0;
	}

       Image[i][j][3] = (GLubyte) 255;
      }

  glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

/*--- Generate 1D stripe image to array stripeImage[] ---*/
  for (j = 0; j < stripeImageWidth; j++) {
     /* When j <= 4, the color is (255, 0, 0),   i.e., red stripe/line.
        When j > 4,  the color is (255, 255, 0), i.e., yellow remaining texture
      */
    stripeImage[4*j] = (GLubyte)    255;
    stripeImage[4*j+1] = (GLubyte) ((j>4) ? 255 : 0);
    stripeImage[4*j+2] = (GLubyte) 0; 
    stripeImage[4*j+3] = (GLubyte) 255;
  }

  glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
/*----------- End 1D stripe image ----------------*/

/*--- texture mapping set-up is to be done in 
      init() (set up texture objects),
      display() (activate the texture object to be used, etc.)
      and in shaders.
 ---*/

} /* end function */