I agree. Not only the COLLADA importer, but also the .egg importer and so on…
The registering system is something I have been pondering too, since it would be a step towards a engine-angostic physics API, but this would mean to remove the current CollisionSolids (and the whole collision system) too. Not my intention.
So far the here presented Bullet code has it’s own collision objects, which get not loaded by Panda3D’s importers. What I am talking about is the next level of Bullet integration. I don’t want to give a date for a first release.
A downside of this is that I will have to add new CollisionSolids, e. g. for convex hulls, concave triangle meshes or heightfields. Not every physics/collision system will support every type of CollisionSolid. For example Bullet won’t support the inverse sphere. Also we have to be careful about the “modifiers” like e. g. “trigger”.
Other downsides are that ODE or PhysX won’t automatically benefit from this way. The modules would have to be rewritten too. I’d say not to start on this until the experimental Bullet integration work’s well.
Finally, the physics objects (rigid bodies) have to “query” the part of the scene graph below them for CollisionSolids, or state changes of CollisionSolids, since the CollisionSolids don’t push such information to these objects.