PyBullet / BulletRobotics:

Implement collisionFilterPlugin, use setCollisionFilterPair to enable or disable collision detection between specific pairs of objects.
Also, expose setCollisionFilterGroupMask as PyBullet API and in urdf using the tag <collision group="1" mask="2"/>.
See examples/pybullet/examples/collisionFilter.py for an example.
PyBullet default: Lower the warmstarting factor, for maximal coordinates rigid bodies for more stable simulation.
Add btCollisionWorld::refreshBroadphaseProxy to easier recreate the broadphase proxy without adding/removing objects to the world.

examples/SharedMemory/SharedMemoryCommands.h

@@ -699,6 +699,23 @@ struct CalculateMassMatrixResultArgs
 	int m_dofCount;
 };
 
+enum b3EnumCollisionFilterFlags
+{
+    B3_COLLISION_FILTER_PAIR=1,
+	B3_COLLISION_FILTER_GROUP_MASK=2,
+};
+
+struct b3CollisionFilterArgs
+{
+	int m_bodyUniqueIdA;
+	int m_bodyUniqueIdB;
+	int m_linkIndexA;
+	int m_linkIndexB;
+	int m_enableCollision;
+	int m_collisionFilterGroup;
+	int m_collisionFilterMask;
+};
+
 struct CalculateInverseKinematicsArgs
 {
 	int m_bodyUniqueId;
@@ -1087,6 +1104,7 @@ struct SharedMemoryCommand
 		struct UserDataRequestArgs m_userDataRequestArgs;
 		struct AddUserDataRequestArgs m_addUserDataRequestArgs;
 		struct UserDataRequestArgs m_removeUserDataRequestArgs;
+		struct b3CollisionFilterArgs m_collisionFilterArgs;
     };
 };