Added ability to get InCenter. translate and rotate Face

Author: photonstorm

src/gameobjects/mesh/Face.js

@@ -5,6 +5,16 @@
  */
 
 var Class = require('../../utils/Class');
+var Vector2 = require('../../math/Vector2');
+
+function GetLength (x1, y1, x2, y2)
+{
+    var x = x1 - x2;
+    var y = y1 - y2;
+    var magnitude = (x * x) + (y * y);
+
+    return Math.sqrt(magnitude);
+}
 
 /**
  * @classdesc
@@ -53,6 +63,127 @@ var Face = new Class({
          * @since 3.50.0
          */
         this.vertex3 = vertex3;
+
+        /**
+         * The face inCenter. Do not access directly, instead use the `getInCenter` method.
+         *
+         * @name Phaser.GameObjects.Face#_inCenter
+         * @type {Phaser.Math.Vector2}
+         * @private
+         * @since 3.50.0
+         */
+        this._inCenter = new Vector2();
+    },
+
+    getInCenter: function ()
+    {
+        var v1 = this.vertex1;
+        var v2 = this.vertex2;
+        var v3 = this.vertex3;
+
+        var d1 = GetLength(v3.x, v3.y, v2.x, v2.y);
+        var d2 = GetLength(v1.x, v1.y, v3.x, v3.y);
+        var d3 = GetLength(v2.x, v2.y, v1.x, v1.y);
+
+        var p = d1 + d2 + d3;
+
+        return this._inCenter.set(
+            (v1.x * d1 + v2.x * d2 + v3.x * d3) / p,
+            (v1.y * d1 + v2.y * d2 + v3.y * d3) / p
+        );
+    },
+
+    translate: function (x, y)
+    {
+        if (y === undefined) { y = 0; }
+
+        var v1 = this.vertex1;
+        var v2 = this.vertex2;
+        var v3 = this.vertex3;
+
+        v1.translate(x, y);
+        v2.translate(x, y);
+        v3.translate(x, y);
+
+        return this;
+    },
+
+    rotate: function (angle, cx, cy)
+    {
+        var x;
+        var y;
+
+        //  No point of rotation? Use the inCenter instead, then.
+        if (cx === undefined && cy === undefined)
+        {
+            var inCenter = this.getInCenter();
+
+            x = inCenter.x;
+            y = inCenter.y;
+        }
+
+        var c = Math.cos(angle);
+        var s = Math.sin(angle);
+
+        var v1 = this.vertex1;
+        var v2 = this.vertex2;
+        var v3 = this.vertex3;
+
+        var tx = v1.x - x;
+        var ty = v1.y - y;
+
+        v1.setPosition(tx * c - ty * s + x, tx * s + ty * c + y);
+
+        tx = v2.x - x;
+        ty = v2.y - y;
+
+        v2.setPosition(tx * c - ty * s + x, tx * s + ty * c + y);
+
+        tx = v3.x - x;
+        ty = v3.y - y;
+
+        v3.setPosition(tx * c - ty * s + x, tx * s + ty * c + y);
+
+        return this;
+    },
+
+    x: {
+
+        get: function ()
+        {
+            return this.getInCenter().x;
+        },
+
+        set: function (value)
+        {
+            var current = this.getInCenter();
+
+            this.translate(value - current.x, 0);
+        }
+
+    },
+
+    y: {
+
+        get: function ()
+        {
+            return this.getInCenter().y;
+        },
+
+        set: function (value)
+        {
+            var current = this.getInCenter();
+
+            this.translate(0, value - current.y);
+        }
+
+    },
+
+    destroy: function ()
+    {
+        this.vertex1 = null;
+        this.vertex2 = null;
+        this.vertex3 = null;
     }
 
 });