From 5cf091656d8f9c1b50d32b1db336dda19c6ba020 Mon Sep 17 00:00:00 2001
From: Mikko Perttunen <cyndis@kapsi.fi>
Date: Sun, 7 Apr 2013 12:55:03 +0300
Subject: [PATCH] Fix projection::perspective.

---
 src/projection.rs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/projection.rs b/src/projection.rs
index f05ef67..d79b1f7 100644
--- a/src/projection.rs
+++ b/src/projection.rs
@@ -8,12 +8,16 @@ use mat::{Mat4, BaseMat4};
 /**
  * Create a perspective projection matrix
  *
+ * Note: the fovy parameter should be specified in degrees.
+ *
  * This is the equivalent of the gluPerspective function, the algorithm of which
  * can be found [here](http://www.opengl.org/wiki/GluPerspective_code).
  */
 #[inline(always)]
 pub fn perspective<T:Copy + Float + Zero + One + FuzzyEq<T> + Add<T,T> + Sub<T,T> + Mul<T,T> + Div<T,T> + Neg<T>>(fovy: T, aspectRatio: T, near: T, far: T) -> Mat4<T> {
-    let ymax = near * tan(radians(fovy));
+    let _2: T = num::cast(2);
+
+    let ymax = near * tan(radians(fovy / _2));
     let xmax = ymax * aspectRatio;
 
     frustum(-xmax, xmax, -ymax, ymax, near, far)