From e05c62725c8c36f017064cf391d4b7bdb2b28785 Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop+git@gmail.com>
Date: Mon, 9 May 2011 17:05:23 -0400
Subject: [PATCH] add guPerspective()

---
 glslUtil/glslUtil.c | 21 +++++++++++++++++++++
 glslUtil/glslUtil.h |  2 ++
 2 files changed, 23 insertions(+)

diff --git a/glslUtil/glslUtil.c b/glslUtil/glslUtil.c
index f681c15..6c3757a 100644
--- a/glslUtil/glslUtil.c
+++ b/glslUtil/glslUtil.c
@@ -117,3 +117,24 @@ void guMatrixFrustum(guMatrix4x4 *m,
     mult[3][2] = -1.0;
     guMatrixMult(m, m, &mult);
 }
+
+void guPerspective(guMatrix4x4 *m, GLfloat fovy, GLfloat aspect,
+        GLfloat near, GLfloat far)
+{
+    int i, j;
+    guMatrix4x4 mult;
+    for (i = 0; i < 4; i++)
+    {
+        for (j = 0; j < 4; j++)
+        {
+            mult[i][j] = 0.0;
+        }
+    }
+    GLfloat f = 1.0 / tan(fovy / 2.0);
+    mult[0][0] = f / aspect;
+    mult[1][1] = f;
+    mult[2][2] = (far + near) / (near - far);
+    mult[2][3] = (2 * far * near) / (near - far);
+    mult[3][2] = -1.0;
+    guMatrixMult(m, m, &mult);
+}
diff --git a/glslUtil/glslUtil.h b/glslUtil/glslUtil.h
index ec03737..ffc4a4f 100644
--- a/glslUtil/glslUtil.h
+++ b/glslUtil/glslUtil.h
@@ -24,6 +24,8 @@ void guMatrixFrustum(guMatrix4x4 *m,
         GLfloat left, GLfloat right,
         GLfloat bottom, GLfloat top,
         GLfloat near, GLfloat far);
+void guPerspective(guMatrix4x4 *m, GLfloat fovy, GLfloat aspect,
+        GLfloat near, GLfloat far);
 
 #ifdef __cplusplus
 }