07-17-2019, 09:19 PM
It's not a bug, it's because when you add a shell to a cloth with tearing enabled, the number of faces in the mesh will change when a tear occurs, even though the number of faces of the underlying (non-shelled) cloth doesn't change. This is due to the fact that new tears create new open edges that must be bridged.
A unified mesh velocity framework is on the todo list, that will eventually support motion blur regardless of changing face counts, but it's probably a way's off. It doesn't help that max has no consistent mesh velocity framework so I have to manually wrangle all the different ways of calculating motion blur offered by each renderer myself.
An admittedly awful but temporary workaround would be to render your camera with multi-pass moblur enabled.
A unified mesh velocity framework is on the todo list, that will eventually support motion blur regardless of changing face counts, but it's probably a way's off. It doesn't help that max has no consistent mesh velocity framework so I have to manually wrangle all the different ways of calculating motion blur offered by each renderer myself.
An admittedly awful but temporary workaround would be to render your camera with multi-pass moblur enabled.