From 6c745890142600be0d5c782a27f389c8af5633bc Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Wed, 9 May 2007 09:26:33 +0000
Subject: [PATCH] Added signOrZero template method, and to
 Matrix_implementation.cpp usage of this method in the get(Quat&) code.

---
 examples/osgunittests/osgunittests.cpp | 13 +++++++++++++
 include/osg/Math                       |  3 +++
 src/osg/Matrix_implementation.cpp      |  6 +++---
 3 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/examples/osgunittests/osgunittests.cpp b/examples/osgunittests/osgunittests.cpp
index 35af6743d..258123b66 100644
--- a/examples/osgunittests/osgunittests.cpp
+++ b/examples/osgunittests/osgunittests.cpp
@@ -314,8 +314,21 @@ void testQuat()
     testQuatRotate(osg::Vec3d(0.0,0.0,-1.0),osg::Vec3d(0.0,0.0,1.0));
 
     testGetQuatFromMatrix();
+
+
+    osg::Matrix matrix(0.5, 0.0, 0.0, 0.0,
+                       0.0, 0.5, 0.0, 0.0,
+                       0.0, 0.0, 0.5, 0.0,
+                       1.0, 1.0, 1.0, 1.0);
+                       
+    osg::Quat quat;
+    matrix.get(quat);
+    
+    osg::notify(osg::NOTICE)<<"Matrix = "<<matrix<<" rotation="<<quat<<std::endl;
+
 }
 
+
 int main( int argc, char** argv )
 {
     osg::ArgumentParser arguments(&argc,argv);
diff --git a/include/osg/Math b/include/osg/Math
index 72aa4c233..7ceca75d2 100644
--- a/include/osg/Math
+++ b/include/osg/Math
@@ -167,6 +167,9 @@ inline T clampBetween(T v,T minimum, T maximum)
 template<typename T>
 inline T sign(T v) { return v<(T)0?(T)-1:(T)1; }
 
+template<typename T>
+inline T signOrZero(T v) { return v<(T)0 ? (T)-1 : ( v>(T)0 ? (T)1 : 0 ); }
+
 template<typename T>
 inline T square(T v) { return v*v; }
 
diff --git a/src/osg/Matrix_implementation.cpp b/src/osg/Matrix_implementation.cpp
index 36e24a122..3cc9facf1 100644
--- a/src/osg/Matrix_implementation.cpp
+++ b/src/osg/Matrix_implementation.cpp
@@ -138,9 +138,9 @@ Quat Matrix_implementation::getRotate() const
     QY = 0.5 * sqrt( osg::maximum( 0.0, 1.0 - _mat[0][0] + _mat[1][1] - _mat[2][2] ) );
     QZ = 0.5 * sqrt( osg::maximum( 0.0, 1.0 - _mat[0][0] - _mat[1][1] + _mat[2][2] ) );
 
-    QX = QX * osg::sign(  _mat[1][2] - _mat[2][1]) ;
-    QY = QY * osg::sign(  _mat[2][0] - _mat[0][2]) ;
-    QZ = QZ * osg::sign(  _mat[0][1] - _mat[1][0]) ;
+    QX = QX * osg::signOrZero(  _mat[1][2] - _mat[2][1]) ;
+    QY = QY * osg::signOrZero(  _mat[2][0] - _mat[0][2]) ;
+    QZ = QZ * osg::signOrZero(  _mat[0][1] - _mat[1][0]) ;
 
     return q;
 }