From cbefaf0dd1709057c0a3ddde251cc537d0560d33 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=BCrg=20Lehni?= <juerg@scratchdisk.com>
Date: Wed, 27 Nov 2013 00:03:03 +0100
Subject: [PATCH] Fix handling of internally cached _angle in Point.

Closes #344.
---
 src/basic/Point.js | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/basic/Point.js b/src/basic/Point.js
index c555a9d8..0a4bef8a 100644
--- a/src/basic/Point.js
+++ b/src/basic/Point.js
@@ -541,6 +541,10 @@ var Point = Base.extend(/** @lends Point# */{
 	},
 
 	setAngle: function(angle) {
+		// We store a reference to _angle internally so we still preserve it
+		// when the vector's length is set to zero, and then anything else.
+		// Note that we cannot rely on it if x and y are something else than 0,
+		// since updating x / y does not automatically change _angle!
 		angle = this._angle = angle * Math.PI / 180;
 		if (!this.isZero()) {
 			var length = this.getLength();
@@ -573,9 +577,13 @@ var Point = Base.extend(/** @lends Point# */{
 	getAngleInRadians: function(/* point */) {
 		// Hide parameters from Bootstrap so it injects bean too
 		if (arguments[0] === undefined) {
-			if (this._angle == null)
-				this._angle = Math.atan2(this.y, this.x);
-			return this._angle;
+			return this.isZero()
+					// Return the preseved angle in case the vector has no
+					// length, and update the internal _angle in case the
+					// vector has a length. See #setAngle() for more
+					// explanations.
+					? this._angle || 0
+					: this._angle = Math.atan2(this.y, this.x);
 		} else {
 			var point = Point.read(arguments),
 				div = this.getLength() * point.getLength();