Added Circle class.

Author: photonstorm

v3/src/geom/circle/Circle.js

@@ -0,0 +1,148 @@
+var Circle = function (x, y, radius)
+{
+    if (x === undefined) { x = 0; }
+    if (y === undefined) { y = 0; }
+    if (radius === undefined) { radius = 0; }
+
+    this.x = x;
+
+    this.y = y;
+
+    this._radius = radius;
+    this._diameter = radius * 2;
+};
+
+Circle.prototype.constructor = Circle;
+
+Circle.prototype = {
+
+    setTo: function (x, y, radius)
+    {
+        this.x = x;
+        this.y = y;
+        this._radius = radius;
+        this._diameter = radius * 2;
+
+        return this;
+    },
+
+    setEmpty: function ()
+    {
+        return this.setTo(0, 0, 0);
+    },
+
+    setPosition: function (x, y)
+    {
+        if (y === undefined) { y = x; }
+
+        this.x = x;
+        this.y = y;
+
+        return this;
+    }
+
+};
+
+Object.defineProperties(Circle.prototype, {
+
+    radius: {
+
+        enumerable: true,
+
+        get: function ()
+        {
+            return this._radius;
+        },
+
+        set: function (value)
+        {
+            this._radius = value;
+            this._diameter = value * 2;
+        }
+
+    },
+
+    diameter: {
+
+        enumerable: true,
+
+        get: function ()
+        {
+            return this._diameter;
+        },
+
+        set: function (value)
+        {
+            this._diameter = value;
+            this._radius = value * 0.5;
+        }
+
+    },
+
+    left: {
+
+        enumerable: true,
+
+        get: function ()
+        {
+            return this.x - this._radius;
+        },
+
+        set: function (value)
+        {
+            this.x = value + this._radius;
+        }
+
+    },
+
+    right: {
+
+        enumerable: true,
+
+        get: function ()
+        {
+            return this.x + this._radius;
+        },
+
+        set: function (value)
+        {
+            this.x = value - this._radius;
+        }
+
+    },
+
+    top: {
+
+        enumerable: true,
+
+        get: function ()
+        {
+            return this.y - this._radius;
+        },
+
+        set: function (value)
+        {
+            this.y = value + this._radius;
+        }
+
+    },
+
+    bottom: {
+
+        enumerable: true,
+
+        get: function ()
+        {
+            return this.y + this._radius;
+        },
+
+        set: function (value)
+        {
+            this.y = value - this._radius;
+        }
+
+    }
+
+});
+
+module.exports = Circle;