From 8832441dd75848cac5c105097396ffb34343c5cb Mon Sep 17 00:00:00 2001
From: Matt Turner <mattst88@gmail.com>
Date: Wed, 10 Oct 2012 18:16:20 -0700
Subject: Do angle addition

---
 data/angle_addition.vert | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/data/angle_addition.vert b/data/angle_addition.vert
index f410305..72d745e 100644
--- a/data/angle_addition.vert
+++ b/data/angle_addition.vert
@@ -5,8 +5,10 @@ uniform float rotation_angle;
 
 void main()
 {
-  gl_Position.x = z.x;
-  gl_Position.y = z.y;
+  float x = z.x * cos(z.y);
+  float y = z.x * sin(z.y);
+  gl_Position.x = x * cos(rotation_angle) - y * sin(rotation_angle);
+  gl_Position.y = x * sin(rotation_angle) + y * cos(rotation_angle);
   gl_Position.z = 0.;
   gl_Position.w = 1.;
   gl_PointSize = 32.;
-- 
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