public void RecordGhostCollisions(PairCachingGhostObject obj)
{
IOverlappingPairCache cache = obj.GetOverlappingPairCache();
ObjectArray<BroadphasePair> pairs = cache.GetOverlappingPairArray();
DiscreteDynamicsWorld world = (PhysicsScene.World as BulletWorldXNA).world;
PersistentManifoldArray manifoldArray = new PersistentManifoldArray();
BroadphasePair collisionPair;
PersistentManifold contactManifold;
CollisionObject objA;
CollisionObject objB;
ManifoldPoint pt;
int numPairs = pairs.Count;
for (int i = 0; i < numPairs; i++)
{
manifoldArray.Clear();
if (LastCollisionDesc < UpdatedCollisions.Length)
break;
collisionPair = world.GetPairCache().FindPair(pairs[i].m_pProxy0, pairs[i].m_pProxy1);
if (collisionPair == null)
continue;
collisionPair.m_algorithm.GetAllContactManifolds(manifoldArray);
for (int j = 0; j < manifoldArray.Count; j++)
{
contactManifold = manifoldArray[j];
int numContacts = contactManifold.GetNumContacts();
objA = contactManifold.GetBody0() as CollisionObject;
objB = contactManifold.GetBody1() as CollisionObject;
for (int p = 0; p < numContacts; p++)
{
pt = contactManifold.GetContactPoint(p);
if (pt.GetDistance() < 0.0f)
{
RecordCollision(this, objA, objB, pt.GetPositionWorldOnA(), -pt.m_normalWorldOnB,pt.GetDistance());
break;
}
}
}
}
}
// Portable static method: prerequisite call: m_dynamicsWorld.getBroadphase().getOverlappingPairCache().setInternalGhostPairCallback(new btGhostPairCallback());
public static void GetCollidingObjectsInsidePairCachingGhostObject(DiscreteDynamicsWorld m_dynamicsWorld, PairCachingGhostObject m_pairCachingGhostObject, ObjectArray<CollisionObject> collisionArrayOut)
{
bool addOnlyObjectsWithNegativeDistance = true; // With "false" things don't change much, and the code is a bit faster and cleaner...
collisionArrayOut.Resize(0);
if (m_pairCachingGhostObject == null || m_dynamicsWorld == null) return;
//#define USE_PLAIN_COLLISION_WORLD // We dispatch all collision pairs of the ghost object every step (slow)
#if USE_PLAIN_COLLISION_WORLD
//======================================================================================================
// I thought this line was no longer needed, but it seems to be necessary (and I believe it's an expensive call):
m_dynamicsWorld.getDispatcher().dispatchAllCollisionPairs(m_pairCachingGhostObject.getOverlappingPairCache(), m_dynamicsWorld.getDispatchInfo(), m_dynamicsWorld.getDispatcher());
// Maybe the call can be automatically triggered by some other Bullet call (I'm almost sure I could comment it out in another demo I made long ago...)
// So by now the general rule is: in real projects, simply comment it out and see if it works!
//======================================================================================================
// UPDATE: in dynamic worlds, the line above can be commented out and the broadphase pair can be retrieved through the call to findPair(...) below.
// In collision worlds probably the above line is needed only if collision detection for all the bodies hasn't been made... This is something
// I'm still not sure of... the general rule is to try to comment out the line above and try to use findPair(...) and see if it works whenever possible....
//======================================================================================================
#endif //USE_PLAIN_COLLISION_WORLD
ObjectArray<BroadphasePair> collisionPairs = m_pairCachingGhostObject.GetOverlappingPairCache().GetOverlappingPairArray();
int numObjects = collisionPairs.Count;
PersistentManifoldArray m_manifoldArray = new PersistentManifoldArray();
bool added;
for (int i = 0; i < numObjects; i++)
{
m_manifoldArray.Resize(0);
#if USE_PLAIN_COLLISION_WORLD
const btBroadphasePair& collisionPair = collisionPairs[i];
if (collisionPair.m_algorithm) collisionPair.m_algorithm.getAllContactManifolds(m_manifoldArray);
else { // THIS SHOULD NEVER HAPPEN, AND IF IT DOES, PLEASE RE-ENABLE the "call" a few lines above...
printf("No collisionPair.m_algorithm - probably m_dynamicsWorld.getDispatcher().dispatchAllCollisionPairs(...) must be missing.\n");
}
#else // USE_PLAIN_COLLISION_WORLD
BroadphasePair cPair = collisionPairs[i];
//unless we manually perform collision detection on this pair, the contacts are in the dynamics world paircache:
BroadphasePair collisionPair = m_dynamicsWorld.GetPairCache().FindPair(cPair.m_pProxy0, cPair.m_pProxy1);
if (collisionPair == null)
{
continue;
}
if (collisionPair.m_algorithm != null)
{
collisionPair.m_algorithm.GetAllContactManifolds(m_manifoldArray);
}
else
{ // THIS SHOULD NEVER HAPPEN, AND IF IT DOES, PLEASE RE-ENABLE the "call" a few lines above...
//printf("No collisionPair.m_algorithm - probably m_dynamicsWorld.getDispatcher().dispatchAllCollisionPairs(...) must be missing.\n");
}
#endif //USE_PLAIN_COLLISION_WORLD
added = false;
for (int j = 0; j < m_manifoldArray.Count; j++)
{
PersistentManifold manifold = m_manifoldArray[j];
// Here we are in the narrowphase, but can happen that manifold.getNumContacts()==0:
if (addOnlyObjectsWithNegativeDistance)
{
for (int p = 0, numContacts = manifold.GetNumContacts(); p < numContacts; p++)
{
ManifoldPoint pt = manifold.GetContactPoint(p);
if (pt.GetDistance() < 0.0)
{
// How can I be sure that the colObjs are all distinct ? I use the "added" flag.
collisionArrayOut.Add((CollisionObject)(manifold.GetBody0() == m_pairCachingGhostObject ? manifold.GetBody1() : manifold.GetBody0()));
added = true;
break;
}
}
if (added)
{
break;
}
}
else if (manifold.GetNumContacts() > 0)
{
collisionArrayOut.Add((CollisionObject)(manifold.GetBody0() == m_pairCachingGhostObject ? manifold.GetBody1() : manifold.GetBody0()));
break;
}
}
}
}
