glstuff

commit 86bd27c721a8a276571dc4396d2262ca710934fb
parent b5ed7965ca22c482dd6833830969a0082fe3cd8e
Author: Brian Swetland <swetland@frotz.net>
Date:   Sun, 20 Jan 2013 09:31:42 -0800

mtx_mul_vec4() for using a mat4 to transform a vec4

Diffstat:
M
util.c
 | 
12
++++++++++++
M
util.h
 | 
3
+++

2 files changed, 15 insertions(+), 0 deletions(-)
diff --git a/util.c b/util.c
@@ -46,6 +46,18 @@ void mtx_mul(mat4 m, mat4 a, mat4 b) {
 	memcpy(m, t, sizeof(mat4));
 }
 
+void mtx_mul_vec4(vec4 o, mat4 m, vec4 v) {
+	float a, b, c, d;
+	a = m[0][0] * v[0] + m[1][0] * v[1] + m[2][0] * v[2] + m[3][0] * v[3];
+	b = m[0][1] * v[0] + m[1][1] * v[1] + m[2][1] * v[2] + m[3][1] * v[3];
+	c = m[0][2] * v[0] + m[1][2] * v[1] + m[2][2] * v[2] + m[3][2] * v[3];
+	d = m[0][3] * v[0] + m[1][3] * v[1] + m[2][3] * v[2] + m[3][3] * v[3];
+	o[0] = a;
+	o[1] = b;
+	o[2] = c;
+	o[3] = d;
+}
+
 void mtx_identity(mat4 m) {
 	memset(m, 0, sizeof(mat4));
 	m[0][0] = m[1][1] = m[2][2] = m[3][3] = 1.0f;
diff --git a/util.h b/util.h
@@ -18,6 +18,7 @@
 
 typedef float mat4[4][4];
 typedef float vec4[4];
+typedef float vec3[3];
 
 /* load the identity matrix */
 void mtx_identity(mat4 out);
@@ -28,6 +29,8 @@ void mtx_mul(mat4 out, mat4 left, mat4 right);
 /* avoids a copy, but out and left may not be the same */
 void mtx_mul_unsafe(mat4 out, mat4 left, mat4 right);
 
+void mtx_mul_vec4(vec4 out, mat4 left, vec4 right);
+
 /* applies the transform to out */
 void mtx_translate(mat4 out, float x, float y, float z);
 void mtx_rotate_x(mat4 out, float angle);