From b3b495e53cf38a90e33c1bb5cbc07fe52502aa25 Mon Sep 17 00:00:00 2001
From: Richard Davey <rdavey@gmail.com>
Date: Wed, 29 Mar 2017 15:05:29 +0100
Subject: [PATCH] Added Rectangle.PerimeterPoint method for getting the point
 on the perimeter of a rectangle based on the given angle.

---
 v3/src/geom/rectangle/PerimeterPoint.js | 66 +++++++++++++++++++++++++
 v3/src/geom/rectangle/index.js          |  1 +
 2 files changed, 67 insertions(+)
 create mode 100644 v3/src/geom/rectangle/PerimeterPoint.js

diff --git a/v3/src/geom/rectangle/PerimeterPoint.js b/v3/src/geom/rectangle/PerimeterPoint.js
new file mode 100644
index 000000000..b9a3ad6a7
--- /dev/null
+++ b/v3/src/geom/rectangle/PerimeterPoint.js
@@ -0,0 +1,66 @@
+var MATH_CONST = require('../../math/const');
+
+//  deg = degrees
+
+var PerimeterPoint = function (rect, deg, out)
+{
+    if (out === undefined) { out = { x: 0, y: 0 }; }
+
+    var theta = deg * MATH_CONST.DEG_TO_RAD;
+
+    while (theta < -Math.PI)
+    {
+        theta += MATH_CONST.PI2;
+    }
+
+    while (theta > Math.PI)
+    {
+        theta -= MATH_CONST.PI2;
+    }
+
+    var rectAtan = Math.atan2(rect.height, rect.width);
+    var tanTheta = Math.tan(theta);
+    var thetaBounds = Math.PI - rectAtan;
+    var region;
+    var xFactor = 1;
+    var yFactor = 1;
+
+    if (theta > -rectAtan && theta <= rectAtan)
+    {
+        region = 1;
+        yFactor = -1;
+    }
+    else if (theta > rectAtan && theta <= thetaBounds)
+    {
+        region = 2;
+        yFactor = -1;
+    }
+    else if (theta > thetaBounds || theta <= -thetaBounds)
+    {
+        region = 3;
+        xFactor = -1;
+    }
+    else
+    {
+        region = 4;
+        xFactor = -1;
+    }
+
+    out.x = rect.x + (rect.width / 2);
+    out.y = rect.y + (rect.height / 2);
+
+    if (region === 1 || region === 3)
+    {
+        out.x += xFactor * (rect.width / 2);                                     // "Z0"
+        out.y += yFactor * (rect.width / 2) * tanTheta;
+    }
+    else
+    {
+        out.x += xFactor * (rect.height / (2 * tanTheta));                        // "Z1"
+        out.y += yFactor * (rect.height / 2);
+    }
+
+    return out;
+};
+
+module.exports = PerimeterPoint;
diff --git a/v3/src/geom/rectangle/index.js b/v3/src/geom/rectangle/index.js
index 6800bc8bd..12c0ddcbc 100644
--- a/v3/src/geom/rectangle/index.js
+++ b/v3/src/geom/rectangle/index.js
@@ -27,6 +27,7 @@ Rectangle.Offset = require('./Offset');
 Rectangle.OffsetPoint = require('./OffsetPoint');
 Rectangle.Overlaps = require('./Overlaps');
 Rectangle.Perimeter = require('./Perimeter');
+Rectangle.PerimeterPoint = require('./PerimeterPoint');
 Rectangle.Random = require('./Random');
 Rectangle.Scale = require('./Scale');
 Rectangle.Union = require('./Union');