Explosion sounds

math.js

@@ -1,4 +1,3 @@
-
 export function index2coords(width, i) {
   return [i % width, Math.floor(i/width)];
 }
@@ -27,6 +26,10 @@ export function wrap(min, x, max) {
   return ((x-min + max-min) % (max-min)) + min;
 }
 
+export function cycle(x, d) {
+  return Math.floor(x / d);
+}
+
 export function within(x, y, tx, ty, r) {
   return Math.abs(x-tx) < r && Math.abs(y-ty) < r;
 }