The bullet shape: btGImpactShape?

I recently asked a question in the Bullet forum:

It seems the cd between trimeshes will lead to wierd physical results.
The suggested solution is btGImpactShape. Is there any plan to include this shape in Panda3d?

There are no plans to add this shape, but this seems like a good, straight-forward feature request to add to the issue tracker. In the meantime, would btConvexHull work for you?

Never mind what I said, I found btGImpactShape is already supported via Panda’s BulletTriangleMeshShape by using dynamic=True in the constructor. This will change the underlying Bullet shape BulletTriangleMeshShape uses under-the-hood from btBvhTriangleMeshShape to btGImpactShape.

Thanks. I also found it in the source.

But anyidea why the problem happens?