handle case where trace is zero in Matrix4x4_ToOrigin3Quat4Float

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@9911 d7cf8633-e32d-0410-b094-e92efae38249

diff --git a/matrixlib.c b/matrixlib.c
index 89c131144dd7e9e71df20dbdbca81b1ad0c20696..266ec14173b6d094fec45efc47bf66b8ae24a678 100644 (file)
--- a/matrixlib.c
+++ b/matrixlib.c
@@ -1430,6 +1430,7 @@ void Matrix4x4_FromOriginQuat(matrix4x4_t *m, double ox, double oy, double oz, d
 // see http://www.euclideanspace.com/maths/geometry/rotations/conversions/matrixToQuaternion/index.htm
 void Matrix4x4_ToOrigin3Quat4Float(const matrix4x4_t *m, float *origin, float *quat)
 {
+#if 0
        float s;
        quat[3] = sqrt(1.0f + m->m[0][0] + m->m[1][1] + m->m[2][2]) * 0.5f;
        s = 0.25f / quat[3];
@@ -1448,6 +1449,86 @@ void Matrix4x4_ToOrigin3Quat4Float(const matrix4x4_t *m, float *origin, float *q
        quat[1] = (m->m[0][2] - m->m[2][0]) * s;
        quat[2] = (m->m[1][0] - m->m[0][1]) * s;
 #endif
+
+#else
+
+#ifdef MATRIX4x4_OPENGLORIENTATION
+       float trace = m->m[0][0] + m->m[1][1] + m->m[2][2];
+       origin[0] = m->m[3][0];
+       origin[1] = m->m[3][1];
+       origin[2] = m->m[3][2];
+       if(trace > 0)
+       {
+               float r = sqrt(1.0f + trace), inv = 0.5f / r;
+               quat[0] = (m->m[1][2] - m->m[2][1]) * inv;
+               quat[1] = (m->m[2][0] - m->m[0][2]) * inv;
+               quat[2] = (m->m[0][1] - m->m[1][0]) * inv;
+               quat[3] = 0.5f * r;
+       }
+       else if(m->m[0][0] > m->m[1][1] && m->m[0][0] > m->m[2][2])
+       {
+               float r = sqrt(1.0f + m->m[0][0] - m->m[1][1] - m->m[2][2]), inv = 0.5f / r;
+               quat[0] = 0.5f * r;
+               quat[1] = (m->m[0][1] + m->m[1][0]) * inv;
+               quat[2] = (m->m[2][0] + m->m[0][2]) * inv;
+               quat[3] = (m->m[1][2] - m->m[2][1]) * inv;
+       }
+       else if(m->m[1][1] > m->m[2][2])
+       {
+               float r = sqrt(1.0f + m->m[1][1] - m->m[0][0] - m->m[2][2]), inv = 0.5f / r;
+               quat[0] = (m->m[0][1] + m->m[1][0]) * inv;
+               quat[1] = 0.5f * r;
+               quat[2] = (m->m[1][2] + m->m[2][1]) * inv;
+               quat[3] = (m->m[2][0] - m->m[0][2]) * inv;
+       }
+       else
+       {
+               float r = sqrt(1.0f + m->m[2][2] - m->m[0][0] - m->m[1][1]), inv = 0.5f / r;
+               quat[0] = (m->m[2][0] + m->m[0][2]) * inv;
+               quat[1] = (m->m[1][2] + m->m[2][1]) * inv;
+               quat[2] = 0.5f * r;
+               quat[3] = (m->m[0][1] - m->m[1][0]) * inv;
+       }
+#else
+       float trace = m->m[0][0] + m->m[1][1] + m->m[2][2];
+       origin[0] = m->m[0][3];
+       origin[1] = m->m[1][3];
+       origin[2] = m->m[2][3];
+       if(trace > 0)
+       {
+               float r = sqrt(1.0f + trace), inv = 0.5f / r;
+               quat[0] = (m->m[2][1] - m->m[1][2]) * inv;
+               quat[1] = (m->m[0][2] - m->m[2][0]) * inv;
+               quat[2] = (m->m[1][0] - m->m[0][1]) * inv;
+               quat[3] = 0.5f * r;
+       }
+       else if(m->m[0][0] > m->m[1][1] && m->m[0][0] > m->m[2][2])
+       {
+               float r = sqrt(1.0f + m->m[0][0] - m->m[1][1] - m->m[2][2]), inv = 0.5f / r;
+               quat[0] = 0.5f * r;
+               quat[1] = (m->m[1][0] + m->m[0][1]) * inv;
+               quat[2] = (m->m[0][2] + m->m[2][0]) * inv;
+               quat[3] = (m->m[2][1] - m->m[1][2]) * inv;
+       }
+       else if(m->m[1][1] > m->m[2][2])
+       {
+               float r = sqrt(1.0f + m->m[1][1] - m->m[0][0] - m->m[2][2]), inv = 0.5f / r;
+               quat[0] = (m->m[1][0] + m->m[0][1]) * inv;
+               quat[1] = 0.5f * r;
+               quat[2] = (m->m[2][1] + m->m[1][2]) * inv;
+               quat[3] = (m->m[0][2] - m->m[2][0]) * inv;
+       }
+       else
+       {
+               float r = sqrt(1.0f + m->m[2][2] - m->m[0][0] - m->m[1][1]), inv = 0.5f / r;
+               quat[0] = (m->m[0][2] + m->m[2][0]) * inv;
+               quat[1] = (m->m[2][1] + m->m[1][2]) * inv;
+               quat[2] = 0.5f * r;
+               quat[3] = (m->m[1][0] - m->m[0][1]) * inv;
+       }
+#endif
+
+#endif
 }
 
 // LordHavoc: I got this code from: