Avoid collision detection/response between anchored (static) soft body cluster and a static/kinematic rigid body

src/BulletSoftBody/btSoftBody.cpp

@@ -2116,11 +2116,17 @@ void					btSoftBody::initializeClusters()
 		c.m_masses.resize(c.m_nodes.size());
 		for(int j=0;j<c.m_nodes.size();++j)
 		{
-			c.m_masses[j]	=	c.m_nodes[j]->m_im>0?1/c.m_nodes[j]->m_im: BT_LARGE_FLOAT;
+			if (c.m_nodes[j]->m_im==0)
-			//c.m_masses[j]	=	c.m_nodes[j]->m_im>0?1/c.m_nodes[j]->m_im: 0.f;
+			{
+				c.m_containsAnchor = true;
+				c.m_masses[j]	=	BT_LARGE_FLOAT;
+			} else
+			{
+				c.m_masses[j]	=	btScalar(1.)/c.m_nodes[j]->m_im;
+			}
 			c.m_imass		+=	c.m_masses[j];
 		}
-		c.m_imass		=	1/c.m_imass;
+		c.m_imass		=	btScalar(1.)/c.m_imass;
 		c.m_com			=	btSoftBody::clusterCom(&c);
 		c.m_lv			=	btVector3(0,0,0);
 		c.m_av			=	btVector3(0,0,0);

src/BulletSoftBody/btSoftBody.h

@@ -310,11 +310,13 @@ public:
 		btScalar					m_matching;
 		btScalar					m_maxSelfCollisionImpulse;
 		btScalar					m_selfCollisionImpulseFactor;
+		bool						m_containsAnchor;
 		bool						m_collide;
 		int							m_clusterIndex;
 		Cluster() : m_leaf(0),m_ndamping(0),m_ldamping(0),m_adamping(0),m_matching(0) 
 		,m_maxSelfCollisionImpulse(100.f),
-		m_selfCollisionImpulseFactor(0.01f)
+		m_selfCollisionImpulseFactor(0.01f),
+		m_containsAnchor(false)
 		{}
 	};
 	/* Impulse		*/ 

src/BulletSoftBody/btSoftBodyInternals.h

@@ -726,6 +726,11 @@ struct btSoftColliders
 			btSoftClusterCollisionShape	cshape(cluster);
 			
 			const btConvexShape*		rshape=(const btConvexShape*)m_colObj->getCollisionShape();
+
+			///don't collide an anchored cluster with a static/kinematic object
+			if(m_colObj->isStaticOrKinematicObject() && cluster->m_containsAnchor)
+				return;
+
 			btGjkEpaSolver2::sResults	res;		
 			if(btGjkEpaSolver2::SignedDistance(	&cshape,btTransform::getIdentity(),
 				rshape,m_colObj->getInterpolationWorldTransform(),