Don't read Math all the time

[rbdr/r.bdr.sh] / js / animation.js

diff --git a/js/animation.js b/js/animation.js
index 65ee4bdec2b32430d47da8d276b47ec00dbcf591..907df5db1c635442bf43002f352a236ac446b56c 100644 (file)
--- a/js/animation.js
+++ b/js/animation.js
@@ -5,15 +5,17 @@
       fps = 30,
       lastFrame = 0,
       speed = 1,
-      size = 5 + rand(10);
+      size = 5 + rand(10),
+      r = Math.random,
+      pi = Math.PI;
 
-  var clear = !!(Math.random() > 0.5);
-  var changeColor = !!(Math.random() > 0.5);
+  var clear = !!(r() > 0.5);
+  var changeColor = !!(r() > 0.5);
   var items = Array(rand(10) + 6).fill(null).map(() => ({
-    x: rand(100),
-    y: rand(100),
-    angle: Math.random() * 2 * Math.PI,
-    color: Array(3).fill(null).map(() => rand(256))
+    x: rand(64),
+    y: rand(64),
+    angle: r() * 2 * pi,
+    color: Array(3).fill(rand(256))
   }));
   var shapes = [square, circle, heart, chaos, lineChaos];
   var positions = [identity, spin(5), spin(15)];
@@ -21,7 +23,7 @@
   var position = positions[rand(positions.length)];
 
   function rand (x) {
-    return Math.floor(Math.random() * x);
+    return Math.floor(r() * x);
   }
 
   function square(item) {
@@ -34,7 +36,7 @@
 
     var p = position(item);
     context.beginPath();
-    context.arc(p.x, p.y, size / 2, 0, 2 * Math.PI);
+    context.arc(p.x, p.y, size / 2, 0, 2 * pi);
     context.fill();
   }
 
@@ -44,7 +46,7 @@
     context.beginPath();
     context.moveTo(p.x, p.y);
     context.lineTo(p.x * 10 * Math.cos(item.angle), p.y * 10 * Math.sin(item.angle));
-    context.lineTo(rand(100), rand(100));
+    context.lineTo(rand(64), rand(64));
     context.fill();
   }
 
@@ -71,12 +73,12 @@
     context.fillRect(p.x, p.y, size, size);
 
     context.beginPath();
-    context.arc(p.x + size / 2, p.y, size / 2, 0, 2 * Math.PI, false);
+    context.arc(p.x + size / 2, p.y, size / 2, 0, 2 * pi, false);
     context.fill();
     context.closePath();
 
     context.beginPath();
-    context.arc(p.x + size, p.y + size / 2, size / 2, 0, 2 * Math.PI, false);
+    context.arc(p.x + size, p.y + size / 2, size / 2, 0, 2 * pi, false);
     context.fill();
     context.closePath();
   }
@@ -101,11 +103,11 @@
     item.x = item.x + speed * Math.cos(item.angle);
     item.y = item.y + speed * Math.sin(item.angle);
 
-    if (item.x < 0 || item.x > 100) {
+    if (item.x < 0 || item.x > 64) {
       item.angle = Math.atan2(Math.sin(item.angle), -Math.cos(item.angle))
     }
 
-    if (item.y < 0 || item.y > 100) {
+    if (item.y < 0 || item.y > 64) {
       item.angle = Math.atan2(-Math.sin(item.angle), Math.cos(item.angle))
     }
   }
@@ -125,7 +127,7 @@
     var delta = time - lastFrame;
 
     if (delta > 1000 / fps) {
-      clear && context.clearRect(0, 0, 100, 100);
+      clear && context.clearRect(0, 0, 64, 64);
       for (var item of items) {
         context.fillStyle = `rgb(${item.color.join(',')})`;
         draw(item);