/* Generate a large nonrepeating image by summing small repeating elements.
 *
 * Because the sizes of the small repeating elements are three
 * successive Fibonacci numbers, they are relatively prime, and their
 * ratios don’t closely approximate simpler ratios.  Nevertheless, the
 * picture has quite a bit of visible regularity, because e.g. every
 * 104 pixels the 8 and 13 cycles coincide, and every 168 pixels the 8
 * and 21 cycles coincide.
 */
#include "ppmp6.h"

enum { ww = 256, hh = 256 };
ppm_p6_color image[ww][hh];

void tile_points(ppm_p6_color color, int dx, int dy)
{
  for (int y = 0; y < hh; y += dy) {
    for (int x = 0; x < ww; x += dx) {
      image[y][x].r += color.r;
      image[y][x].g += color.g;
      image[y][x].b += color.b;
    }
  }
}

int main(int argc, char **argv)
{
  ppm_p6_color red = { 128, 0, 0 };
  tile_points(red, 8, 21);
  ppm_p6_color green = { 0, 128, 0 };
  tile_points(green, 13, 13);
  ppm_p6_color cerulean = { 64, 64, 255 };
  tile_points(cerulean, 21, 8);

  ppm_p6_output_image(image[0], ww, hh);
  return 0;
}