Collision Groups

[jc211]

In warp.sim.ModelBuilder, instead of building self.shape_collision_group_map on every builder._add_shape, maybe it can be built in builder.finalize(). That way, I can change the shape_collision_group of each shape before finalizing the model and these changes will propagate into the datastructures needed for the model. Additionally, instead of using a default collision_group of -1, can it instead use a new builder.default_collision_group. This way, builder.set_default_collision_group() can be used to specify the required collision group for every new shape added including those adding during urdf imports.