Added RotateAroundDistance and tidied up other Rotate functions.

Author: photonstorm

v3/src/math/Rotate.js

@@ -1,13 +1,14 @@
 //  p = Point or any object with public x/y properties
-var Rotate = function (p, angle)
+
+var Rotate = function (point, angle)
 {
-    var x = p.x;
-    var y = p.y;
+    var x = point.x;
+    var y = point.y;
 
-    p.x = x * Math.cos(angle) - y * Math.sin(angle);
-    p.y = x * Math.sin(angle) + y * Math.cos(angle);
+    point.x = (x * Math.cos(angle)) - (y * Math.sin(angle));
+    point.y = (x * Math.sin(angle)) + (y * Math.cos(angle));
 
-    return p;
+    return point;
 };
 
 module.exports = Rotate;

v3/src/math/RotateAround.js

@@ -1,16 +1,17 @@
 //  p = Point or any object with public x/y properties
-var RotateAround = function (p, cx, cy, angle)
+
+var RotateAround = function (point, x, y, angle)
 {
     var c = Math.cos(angle);
     var s = Math.sin(angle);
 
-    var x = p.x - cx;
-    var y = p.y - cy;
+    var tx = point.x - x;
+    var ty = point.y - y;
 
-    p.x = x * c - y * s + cx;
-    p.y = x * s + y * c + cy;
+    point.x = tx * c - ty * s + x;
+    point.y = tx * s + ty * c + y;
 
-    return p;
+    return point;
 };
 
 module.exports = RotateAround;

v3/src/math/RotateAroundDistance.js

@@ -0,0 +1,13 @@
+//  p = Point or any object with public x/y properties
+
+var RotateAroundDistance = function (point, x, y, angle, distance)
+{
+    var t = angle + Math.atan2(point.y - y, point.x - x);
+
+    point.x = x + (distance * Math.cos(t));
+    point.y = y + (distance * Math.sin(t));
+
+    return point;
+};
+
+module.exports = RotateAroundDistance;

v3/src/math/index.js

@@ -35,6 +35,7 @@ module.exports = {
     RadToDeg: require('./RadToDeg'),
     Rotate: require('./Rotate'),
     RotateAround: require('./RotateAround'),
+    RotateAroundDistance: require('./RotateAroundDistance'),
     RoundAwayFromZero: require('./RoundAwayFromZero'),
     RoundTo: require('./RoundTo'),
     SinCosTableGenerator: require('./SinCosTableGenerator'),