Draws a glider flag

glider.c

/*
 * ./this width height topRGB bottomRGB [circleSizeDivFactor=4]
 * ./this 800 600 FFFFFF 000000 | feh -
 */
#include <math.h>
#include <stdio.h>
#include <stdlib.h>

#define PRINT(c) do { printf("%d %d %d ", c >> 16, c >> 8 & 0xFF, c & 0xFF); } while(0)
#define IN_CIRCLE(x, y) ((i - y) * (i - y) + (j - x) * (j - x) <= r*r)

int
main(int argc, char **argv)
{
  int factor = 4;
  if (argc < 5)
    return 1;
  if (argc >= 6)
    factor = atoi(argv[5]);
  int w = atoi(argv[1]),
      h = atoi(argv[2]),
      w3i = w / 3,
      h3i = h / 3,
      r = sqrt(w3i * w3i + h3i * h3i) / factor,
      c01i = h / 6,
      c01j = w / 2,
      c12i = h / 2,
      c12j = w - w / 6,
      c20i = h - h / 6,
      c20j = w / 6,
      c21i = h - h / 6,
      c21j = w / 2,
      c22i = h - h / 6,
      c22j = w - w / 6,
      color1 = strtol(argv[3], 0, 16),
      color2 = strtol(argv[4], 0, 16);
  printf("P3 %d %d 255 ", w, h);
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      int z = h - i;
      if (IN_CIRCLE(c01j, c01i) ||
          (IN_CIRCLE(c20j, c20i) && (z*w) - (j*h) > 0) ||
          ((z*w) - (j*h) <= 0 &&
           !IN_CIRCLE(c12j, c12i) &&
           !IN_CIRCLE(c20j, c20i) &&
           !IN_CIRCLE(c21j, c21i) &&
           !IN_CIRCLE(c22j, c22i)))
        PRINT(color1);
      else
        PRINT(color2);
    }
  }
  return 0;
}