raycast collision filter C API

[goretkin]

It seems that the raycast operations support collision filtering.

I think this these are the flags that need to be set:

bullet3/src/BulletCollision/CollisionDispatch/btCollisionWorld.h

Lines 199 to 201 in 7a7652f

	int m_collisionFilterGroup;
	int m_collisionFilterMask;
	//@BP Mod - Custom flags, currently used to enable backface culling on tri-meshes, see btRaycastCallback.h. Apply any of the EFlags defined there on m_flags here to invoke.

which are checked in needsCollision

bullet3/src/BulletCollision/CollisionDispatch/btCollisionWorld.h

Lines 224 to 225 in 7a7652f

	bool collides = (proxy0->m_collisionFilterGroup & m_collisionFilterMask) != 0;
	collides = collides && (m_collisionFilterGroup & proxy0->m_collisionFilterMask);

which is invoked here:

bullet3/src/BulletSoftBody/btSoftMultiBodyDynamicsWorld.cpp

Line 220 in 7a7652f

if (m_resultCallback.needsCollision(collisionObject->getBroadphaseHandle()))

It seems the opportunity to set the flags is here:

bullet3/examples/SharedMemory/PhysicsServerCommandProcessor.cpp

Line 5288 in 7a7652f

btCollisionWorld::ClosestRayResultCallback rayResultCallback(rayFromWorld, rayToWorld);

Does this seem right? If the API were to be extended, that's where it would be?