added Matrix4x4_OriginFromMatrix, and Matrix4x4_ScaleFromMatrix

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@2804 d7cf8633-e32d-0410-b094-e92efae38249

diff --git a/matrixlib.c b/matrixlib.c
index 5d4279bf99fa406567729bcaa3919584e5e07dfe..4fa58d79f0d84f0d14e5f0e747031310d2c7f214 100644 (file)
--- 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 e6d817ba1056f526b36e6eb0f1a78721849365a3..87b09f84dc123cb19bd30dae48c84a963ec4ac4d 100644 (file)
--- 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