Change Details

The problem was that copying a `CDDerivedMesh` doesn't copy the `vert_normals` reference that it takes from a mesh. Since this entire area is almost completely broken anyway (mainly in terms of ownership handling), for now we can just avoid copying the `DerivedMesh` in the zero levels case. Longer term, this area should be refactored to remove `DerivedMesh` and use the newer subdivision evaluation system.

The problem was that copying a `CDDerivedMesh` (`CDDM_copy`) doesn't copy the `vert_normals` reference that it takes from a mesh. Since this entire area is almost completely broken anyway (mainly in terms of ownership handling), for now we can just avoid copying the `DerivedMesh` in the zero levels case. Longer term, this area should be refactored to remove `DerivedMesh` and use the newer subdivision evaluation system.

The problem was that copying a `CDDerivedMesh` doesn't (`CDDM_copy`) doesn't copy the `vert_normals` reference that it takes from a mesh. Since this entire area is almost completely broken anyway (mainly in terms of ownership handling), for now we can just avoid copying the `DerivedMesh` in the zero levels case. Longer term, this area should be refactored to remove `DerivedMesh` and use the newer subdivision evaluation system.