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DuckQueen
DuckQueen

Reputation: 810

Does btGhostObject allow use of complex meshes (not only AABB)?

It is sad in its docs:

The btGhostObject can keep track of all objects that are overlapping By default, this overlap is based on the AABB This is useful for creating a character controller, collision sensors/triggers, explosions etc

Does it mean it is only AABB of its underlying mesh and so detects only collisions with AABB and not complex mesh structure?

Upvotes: 1

Views: 498

Answers (2)

Avi
Avi

Reputation: 1193

As of 2024.04, grabbing the latest BT library version, I am able to create a btGhostObject with TriMesh shape, and detect collision between it, and other dynamic rigid bodies, by iterating over the manifolds in a tick callback function. In my case, that's all I needed to have trigger volumes in my scenes.

Upvotes: 0

rkhayrov
rkhayrov

Reputation: 10260

There is no difference for collision dispatcher between a ghost object and a rigid body: they behave the same way both in broad- and narrow-phase. If you iterate over dispatcher's manifold array, you'll see proper collisions with ghost objects. Documentation refers to the btGhostObject internal overlapping objects cache accessible via getOverlappingObject(int index) / getNumOverlappingObjects() methods. This cache is populated in the broadphase (thus obviously using only AABB), and you have to set the proper pair callback for this to work (world->getPairCache()->setInternalGhostPairCallback(new btGhostPairCallback);). You can iterate over this cache in the post-tick and check for the actual collisions.

Upvotes: 3

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