Add scr directory

src/vec2.js

@@ -0,0 +1,64 @@
+function Vec2(x, y) {
+  this.x = x || 0;
+  this.y = y || 0;
+  return this;
+}
+
+Vec2.prototype.add = function(v) {
+  this.x += v.x;
+  this.y += v.y;
+  return this;
+};
+
+Vec2.prototype.subtract = function(v) {
+  this.x -= v.x;
+  this.y -= v.y;
+  return this;
+};
+
+Vec2.prototype.scale = function(s) {
+  this.x = this.x * s;
+  this.y = this.y * s;
+  return this;
+};
+
+Vec2.prototype.scaleTo = function(s) {
+  var length = this.length();
+  this.x = this.x * s / length;
+  this.y = this.y * s / length;
+  return this;
+};
+
+Vec2.prototype.normalize = function() {
+  var length = this.length();
+  this.x = this.x / length;
+  this.y = this.y / length;
+  return this;
+};
+
+Vec2.prototype.length = function() {
+  return Math.sqrt(this.x * this.x + this.y * this.y);
+};
+
+Vec2.prototype.truncate = function(max) {
+  var length = this.length();
+  if (length > max) {
+    this.x = this.x * max / length;
+    this.y = this.y * max / length;
+  }
+  return this;
+};
+
+Vec2.prototype.dot = function(v) {
+  return this.x * v.x + this.y * v.y;
+};
+
+Vec2.prototype.clone = function() {
+  return new Vec2(this.x, this.y);
+};
+
+Vec2.prototype.turn = function(a) {
+  this.x = this.x * Math.cos(a) - this.y * Math.sin(a),
+  this.y = this.x * Math.sin(a) + this.y * Math.cos(a)
+  return this;
+};