This feature ensures that shapes are only assigned matrix index attributes such as PositionMatrixIdx and Tex0Matrix - Tex7Matrix if the shape being assigned is under the influence of more than 1 joint. The vertices in each mesh are still assigned PositionMatrixIdx attributes to ensure they still have envelope matrix packets in EVP1.
This feature ensures that shapes are only assigned matrix index attributes such as PositionMatrixIdx and Tex0Matrix - Tex7Matrix if the shape being assigned is under the influence of more than 1 joint. The vertices in each mesh are still assigned PositionMatrixIdx attributes to ensure they still have envelope matrix packets in EVP1.