#include <npic.h>

void my_draw (Npic_image *np1)
{
    if (NpicImageIsOK (np1, __func__) != NPIC_SUCCESS)
        return;
        
    switch (np1->type) {
    
        case NPIC_IMAGE_2L : {
            Npic_image_2l *p1 = NpicCastImage (np1); 
            int x, y;
        
            for (y = 0; y < p1->ymax; y++)
            for (x = 0; x < p1->xmax; x++)
                p1->pix[y][x] = (x + y) % 16;
            return;
        } 
        
        case NPIC_IMAGE_3L : {
            Npic_image_3l *p1 = NpicCastImage (np1); 
            int x, y, z;
        
            for (z = 0; z < p1->zmax; z++)
            for (y = 0; y < p1->ymax; y++)
            for (x = 0; x < p1->xmax; x++)
                p1->pix[z][y][x] = (x + y + z) % 16;
            return;
        } 
        
        default : 
            np1->gen.ok = NpicError (__func__, NPIC_ERR_UNEX_NPIC, "");
    }
} 

int main ()
{
    Npic_image *np1;
    
    /* Create a 2L image = 2D image with signed long pixels (4 bytes). height 
       is ymax=12, width is xmax=20, external borders are ybor=0, xbor=0. */
    np1 = NpicCreateImage_2l (12, 20, 0, 0);
    if (np1 == NULL) exit (1);
    
    /* Assign values to pixels */
    my_draw (np1);
  
    /* Print image */
    NpicPrintImage (np1);
    
    /* Destroy image */
    NpicDestroyImage (np1);
    exit(0);
}