make Matrix_ToBonePose6s check the podality of quaternions rather than assuming they...

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@9916 d7cf8633-e32d-0410-b094-e92efae38249
::stable-branch::merge=496e272607d62182e3ab552ba67667fa752d1548

diff --git a/matrixlib.c b/matrixlib.c
index 266ec14173b6d094fec45efc47bf66b8ae24a678..e15fb995f3248de63a8d35b7985ee533d4b09125 100644 (file)
--- a/matrixlib.c
+++ b/matrixlib.c
@@ -1569,26 +1569,20 @@ void Matrix4x4_ToBonePose6s(const matrix4x4_t *m, float origininvscale, short *p
 {
        float origin[3];
        float quat[4];
-       float s;
+       float quatscale;
        Matrix4x4_ToOrigin3Quat4Float(m, origin, quat);
        // normalize quaternion so that it is unit length
-       s = quat[0]*quat[0]+quat[1]*quat[1]+quat[2]*quat[2]+quat[3]*quat[3];
-       if (s)
-       {
-               s = 1.0f / sqrt(s);
-               quat[0] *= s;
-               quat[1] *= s;
-               quat[2] *= s;
-               quat[3] *= s;
-       }
+       quatscale = quat[0]*quat[0]+quat[1]*quat[1]+quat[2]*quat[2]+quat[3]*quat[3];
+       if (quatscale)
+               quatscale = (quat[3] >= 0 ? -32767.0f : 32767.0f) / sqrt(quatscale);
        // use a negative scale on the quat because the above function produces a
        // positive quat[3] and canonical quaternions have negative quat[3]
        pose6s[0] = origin[0] * origininvscale;
        pose6s[1] = origin[1] * origininvscale;
        pose6s[2] = origin[2] * origininvscale;
-       pose6s[3] = quat[0] * -32767.0f;
-       pose6s[4] = quat[1] * -32767.0f;
-       pose6s[5] = quat[2] * -32767.0f;
+       pose6s[3] = quat[0] * quatscale;
+       pose6s[4] = quat[1] * quatscale;
+       pose6s[5] = quat[2] * quatscale;
 }
 
 void Matrix4x4_Blend (matrix4x4_t *out, const matrix4x4_t *in1, const matrix4x4_t *in2, double blend)