dr = floor(maxradius * h) - r0 + 1;
for (i=0;i<n;i++) {
- c[i].r = r0 + random() % dr;
+ c[i].r = r0 + ((dr > 0) ? random() % dr : 0);
c[i].x = c[i].r + frand(w - 1 - 2 * c[i].r);
c[i].y = c[i].r + frand(h - 1 - 2 * c[i].r);
c[i].visible = random() & 1;