From 0a7b1afb5f0835013d5aa201f1c0fc8707afff53 Mon Sep 17 00:00:00 2001
From: Wolfgang Draxinger <Wolfgang.Draxinger@draxit.de>
Date: Sat, 5 Jan 2013 15:58:32 +0100
Subject: fixed some bugs in mat4x4_rotate and mat4x4_ortho

---
 README    |  2 +-
 linmath.h | 48 +++++++++++++++++++++++-------------------------
 2 files changed, 24 insertions(+), 26 deletions(-)

diff --git a/README b/README
index 95bb9d3..9c43c8e 100644
--- a/README
+++ b/README
@@ -7,6 +7,6 @@ vec4 -- 4 element vector of floats (4th component used for homogenous computatio
 mat4x4 -- 4 by 4 elements matrix, computations are done in column major order
 quat -- quaternion
 
-The types are deliberately names like the types in GLSL. In fact they are meant to
+The types are deliberately named like the types in GLSL. In fact they are meant to
 be used for the client side computations and passing to same typed GLSL uniforms.
 
diff --git a/linmath.h b/linmath.h
index a1f4842..1a87ca9 100644
--- a/linmath.h
+++ b/linmath.h
@@ -1,9 +1,3 @@
-/* This program is free software. It comes without any warranty, to
- * the extent permitted by applicable law. You can redistribute it
- * and/or modify it under the terms of the Do What The Fuck You Want
- * To Public License, Version 2, as published by Sam Hocevar. See
- * http://sam.zoy.org/wtfpl/COPYING for more details. */
-
 #ifndef LINMATH_H
 #define LINMATH_H
 
@@ -130,17 +124,17 @@ static inline void mat4x4_sub(mat4x4 M, mat4x4 a, mat4x4 b)
 	for(i=0; i<4; ++i)
 		vec4_sub(M[i], a[i], b[i]);
 }
-static inline void mat4x4_scale_isotropic(mat4x4 M, mat4x4 a, float k)
+static inline void mat4x4_scale(mat4x4 M, mat4x4 a, float k)
 {
 	int i;
 	for(i=0; i<4; ++i)
 		vec4_scale(M[i], a[i], k);
 }
-static inline void mat4x4_scale(mat4x4 R, mat4x4 M, float sx, float sy, float sz)
+static inline void mat4x4_scale_aniso(mat4x4 M, mat4x4 a, float x, float y, float z)
 {
-	vec4_scale(R[0], M[0], sx);
-	vec4_scale(R[1], M[1], sy);
-	vec4_scale(R[2], M[2], sz);
+	vec4_scale(M[0], a[0], x);
+	vec4_scale(M[1], a[1], y);
+	vec4_scale(M[2], a[2], z);
 }
 static inline void mat4x4_mul(mat4x4 M, mat4x4 a, mat4x4 b)
 {
@@ -180,7 +174,7 @@ static inline void mat4x4_from_vec3_mul_outer(mat4x4 M, vec3 a, vec3 b)
 		M[i][j] = i<3 && j<3 ? a[i] * b[j] : 0.;
 	}
 }
-static inline void mat4x4_rotate(mat4x4 Q, mat4x4 M, float x, float y, float z, float angle)
+static inline void mat4x4_rotate(mat4x4 R, mat4x4 M, float x, float y, float z, float angle)
 {
 	float s = sinf(angle);
 	float c = cosf(angle);
@@ -189,23 +183,27 @@ static inline void mat4x4_rotate(mat4x4 Q, mat4x4 M, float x, float y, float z,
 
 	{
 		mat4x4 T;
+		mat4x4_from_vec3_mul_outer(T, u, u);
+
 		mat4x4 S = {
 			{    0,  u[2], -u[1], 0},
 			{-u[2],     0,  u[0], 0},
 			{ u[1], -u[0],     0, 0},
-			{    0,     0,     0, 1}
+			{    0,     0,     0, 0}
 		};
-		mat4x4_scale_isotropic(S, S, s);
+		mat4x4_scale(S, S, s);
+
+		mat4x4 C;
+		mat4x4_identity(C);
+		mat4x4_sub(C, C, T);
+
+		mat4x4_scale(C, C, c);
 
-		mat4x4 R;
-		mat4x4_from_vec3_mul_outer(R, u, u);
-		mat4x4_identity(T);
-		mat4x4_sub(T, T, Q);
-		T[3][3] = 0.;
-		mat4x4_scale_isotropic(T, T, c);
+		mat4x4_add(T, T, C);
+		mat4x4_add(T, T, S);
 
-		mat4x4_add(R, R, T);
-		mat4x4_add(Q, R, S);
+		T[3][3] = 1.;		
+		mat4x4_mul(R, M, T);
 	}
 }
 static inline void mat4x4_rotate_X(mat4x4 Q, mat4x4 M, float angle)
@@ -318,9 +316,9 @@ static inline void mat4x4_ortho(mat4x4 M, float l, float r, float b, float t, fl
 	M[2][2] = -2./(f-n);
 	M[2][0] = M[2][1] = M[2][3] = 0.;
 	
-	M[3][0] = (r+l)/(r-l);
-	M[3][1] = (t+b)/(t-b);
-	M[3][2] = (f+n)/(f-n);
+	M[3][0] = -(r+l)/(r-l);
+	M[3][1] = -(t+b)/(t-b);
+	M[3][2] = -(f+n)/(f-n);
 	M[3][3] = 1.;
 }
 
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