From f30e31df30fef4984bf13f4f7dc36fce6b464a53 Mon Sep 17 00:00:00 2001
From: havoc <havoc@d7cf8633-e32d-0410-b094-e92efae38249>
Date: Fri, 7 Mar 2003 09:23:33 +0000
Subject: [PATCH] added Matrix4x4_OriginFromMatrix, and
 Matrix4x4_ScaleFromMatrix

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@2804 d7cf8633-e32d-0410-b094-e92efae38249
---
 matrixlib.c | 13 +++++++++++++
 matrixlib.h |  5 +++++
 2 files changed, 18 insertions(+)

diff --git a/matrixlib.c b/matrixlib.c
index 5d4279bf..4fa58d79 100644
--- a/matrixlib.c
+++ b/matrixlib.c
@@ -421,3 +421,16 @@ void Matrix4x4_ConcatScale3 (matrix4x4_t *out, float x, float y, float z)
 	Matrix4x4_Concat(out, &base, &temp);
 }
 
+void Matrix4x4_OriginFromMatrix (const matrix4x4_t *in, float *out)
+{
+	out[0] = in->m[0][3];
+	out[1] = in->m[1][3];
+	out[2] = in->m[2][3];
+}
+
+float Matrix4x4_ScaleFromMatrix (const matrix4x4_t *in)
+{
+	// we only support uniform scaling, so assume the first row is enough
+	return sqrt(in->m[0][0] * in->m[0][0] + in->m[0][1] * in->m[0][1] + in->m[0][2] * in->m[0][2]);
+}
+
diff --git a/matrixlib.h b/matrixlib.h
index e6d817ba..87b09f84 100644
--- a/matrixlib.h
+++ b/matrixlib.h
@@ -85,4 +85,9 @@ void Matrix4x4_ConcatScale (matrix4x4_t *out, float x);
 // immediately applies a Scale3 to the matrix
 void Matrix4x4_ConcatScale3 (matrix4x4_t *out, float x, float y, float z);
 
+// extracts origin vector (translate) from matrix
+void Matrix4x4_OriginFromMatrix (const matrix4x4_t *in, float *out);
+// extracts scaling factor from matrix (only works for uniform scaling)
+float Matrix4x4_ScaleFromMatrix (const matrix4x4_t *in);
+
 #endif
-- 
2.39.2