expose choice of contraint solver in PyBullet, with switchConstraintSolver example

src/BulletDynamics/ConstraintSolver/btConstraintSolver.h

@@ -34,7 +34,8 @@ enum btConstraintSolverType
 {
 	BT_SEQUENTIAL_IMPULSE_SOLVER=1,
 	BT_MLCP_SOLVER=2,
-	BT_NNCG_SOLVER=4
+	BT_NNCG_SOLVER=4,
+    BT_MULTIBODY_SOLVER=8,
 };
 
 class btConstraintSolver

src/BulletDynamics/Featherstone/btMultiBodyDynamicsWorld.cpp

@@ -277,7 +277,11 @@ struct MultiBodyInplaceSolverIslandCallback : public btSimulationIslandManager::
 		m_multiBodyConstraints.resize(0);
 	}
 
-	
+    void    setMultiBodyConstraintSolver(btMultiBodyConstraintSolver* solver)
+    {
+        m_solver = solver;
+    }
+    
 	virtual	void	processIsland(btCollisionObject** bodies,int numBodies,btPersistentManifold**	manifolds,int numManifolds, int islandId)
 	{
 		if (islandId<0)
@@ -394,6 +398,22 @@ btMultiBodyDynamicsWorld::~btMultiBodyDynamicsWorld ()
 	delete m_solverMultiBodyIslandCallback;
 }
 
+void    btMultiBodyDynamicsWorld::setMultiBodyConstraintSolver(btMultiBodyConstraintSolver* solver)
+{
+    m_multiBodyConstraintSolver = solver;
+    m_solverMultiBodyIslandCallback->setMultiBodyConstraintSolver(solver);
+    btDiscreteDynamicsWorld::setConstraintSolver(solver);
+}
+
+void    btMultiBodyDynamicsWorld::setConstraintSolver(btConstraintSolver* solver)
+{
+    if (solver->getSolverType()==BT_MULTIBODY_SOLVER)
+    {
+        m_multiBodyConstraintSolver = (btMultiBodyConstraintSolver*)solver;
+    }
+    btDiscreteDynamicsWorld::setConstraintSolver(solver);
+}
+
 void	btMultiBodyDynamicsWorld::forwardKinematics()
 {
 
@@ -1008,4 +1028,4 @@ void	btMultiBodyDynamicsWorld::serializeMultiBodies(btSerializer* serializer)
 		}
 	}
 
-}
+}

src/BulletDynamics/Featherstone/btMultiBodyDynamicsWorld.h

@@ -109,6 +109,8 @@ public:
 	virtual void applyGravity();
 	
 	virtual	void	serialize(btSerializer* serializer);
+	virtual void	setMultiBodyConstraintSolver(btMultiBodyConstraintSolver* solver);
+    virtual void    setConstraintSolver(btConstraintSolver* solver);
 
 };
 #endif //BT_MULTIBODY_DYNAMICS_WORLD_H