add a btFixedConstraint with toggle between btGeneric6DofConsraint and btFixedConstraint in VoronoiFractureDemo

src/BulletDynamics/ConstraintSolver/btFixedConstraint.h

@@ -0,0 +1,49 @@
+/*
+Bullet Continuous Collision Detection and Physics Library
+Copyright (c) 2013 Erwin Coumans  http://bulletphysics.org
+
+This software is provided 'as-is', without any express or implied warranty.
+In no event will the authors be held liable for any damages arising from the use of this software.
+Permission is granted to anyone to use this software for any purpose, 
+including commercial applications, and to alter it and redistribute it freely, 
+subject to the following restrictions:
+
+1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
+2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
+3. This notice may not be removed or altered from any source distribution.
+*/
+
+#ifndef BT_FIXED_CONSTRAINT_H
+#define BT_FIXED_CONSTRAINT_H
+
+#include "btTypedConstraint.h"
+
+ATTRIBUTE_ALIGNED16(class) btFixedConstraint : public btTypedConstraint
+{
+	btVector3 m_pivotInA;
+	btVector3 m_pivotInB;
+	btQuaternion m_relTargetAB;
+
+public:
+	btFixedConstraint(btRigidBody& rbA,btRigidBody& rbB, const btTransform& frameInA,const btTransform& frameInB);
+	
+	virtual ~btFixedConstraint();
+
+	
+	virtual void getInfo1 (btConstraintInfo1* info);
+
+	virtual void getInfo2 (btConstraintInfo2* info);
+
+	virtual	void	setParam(int num, btScalar value, int axis = -1)
+	{
+		btAssert(0);
+	}
+	virtual	btScalar getParam(int num, int axis = -1) const
+	{
+		btAssert(0);
+		return 0.f;
+	}
+
+};
+
+#endif //BT_FIXED_CONSTRAINT_H