Test pack: ctm_blockstate_submodel.zip

Expectation: Where you see Cobble Posts, they should be incased in glass itself. However the glass doesn't render because Forge isn't rendering the submodel.

Also provided: Working glass models, not used as submodels.

The cause is that the layer checks don't pass through the multipart model. There's not much I can do about this, without significantly slowing down layer checks. The fix is to set the block layer properly in code.