Retrieve the collision of specific compound shape inside a hierarchy.

[DarioMaggiari]

Hello,

this isn't a specific issue, but a "feature enhancement". Let's assume we have a compound shape hierarchy like this:

CompoundShape0
       |------> CollisionShape0
       |------> CompoundShape1
                          |------> CollisionShape1
                          |------> CompoundShape2
                                             |------> CollisionShape2
                          |------> CompoundShape3
                                             |------> CollisionShape3

We have some CompoundShape as child and neighborhood. We need to retrieve the specific CompoundShape when a collision happens. So we need to propagate the CompoundShape level, which is in collision, inside the tree.

The patch proposed, hijack the btCompoundCollisionAlgorithm (ProcessChildShape method) calculating the level and propagating this information using setShapeIdentifiersA. Then, these information will be available inside the customMaterialCombinerContactAddedCallback for the specific evaluation.

Let me know if it can be useful. Based on Bullet 2.88. This is discussed originally here (without the neighborhood checks):

https://pybullet.org/Bullet/phpBB3/viewtopic.php?f=9&t=12650

btManifoldResult.cpp_PATCH.txt

btCompoundCollisionAlgorithm.cpp_PATCH.txt

Best regards,

bye Dario