void NodeTrackerManipulator::setByMatrix(const osg::Matrixd& matrix)
{
osg::Vec3d eye,center,up;
matrix.getLookAt(eye,center,up,_distance);
computePosition(eye,center,up);
}
/** Set the position of the manipulator using a 4x4 matrix.*/
void OrbitCameraManipulator::setByMatrix( const osg::Matrixd& matrix )
{
matrix.getLookAt( m_eye, m_lookat, m_up );
}