ClosestPoint

[Romain Daize]

Hi,

It seems there is no simple API to compute ClosestPoints between two objects. Using btGjkPairDetector is the only way to do this ? SweepTest ignore objects penetrating at start of the path and sometime these may be needed, computing these intersections by the way should be faster, shouldnt be ?

Thanks

Romain

[Romain Daize]

*up*

[Erwin Coumans]

Another simple way of computing the closest points is using the collision dispatcher and the following 3 lines of code:

Code: Select all

	btCollisionAlgorithm* algo = collisionWorld->getDispatcher()->findAlgorithm(&objects[0],&objects[1]);
	btManifoldResult contactPointResult(&objects[0],&objects[1]);
	algo->processCollision(&objects[0],&objects[1],collisionWorld->getDispatchInfo(),&contactPointResult);

Then you can get access to the contact points (closest points) using

Code: Select all

	btManifoldArray manifoldArray;
	algo->getAllContactManifolds(manifoldArray);
	int numManifolds = manifoldArray.size();
	for (i=0;i<numManifolds;i++)
	{
		btPersistentManifold* contactManifold = manifoldArray[i];
		btCollisionObject* obA = static_cast<btCollisionObject*>(contactManifold->getBody0());
		btCollisionObject* obB = static_cast<btCollisionObject*>(contactManifold->getBody1());
		int numContacts = contactManifold->getNumContacts();
		for (int j=0;j<numContacts;j++)
		{
			btManifoldPoint& pt = contactManifold->getContactPoint(j);
			btVector3 ptA =pt.getPositionWorldOnA();
			btVector3 ptB = pt.getPositionWorldOnB();
		}
	}

Is that what you need?
Cheers,
Erwin

[Romain Daize]

Yes that's it. Thanks for the reply. The other point concerns the SweepTest which seems to compute closestPoints at start of the cast but does not provide the result of this start collector, this should be great if we could have cast results at start added to the "along the path" results.