Return a pointer to the u16 index data for sub-mesh submesh of mesh mesh_idx.
Returns null if the mesh uses u32 indices or the indices are out of range.
out_len receives the number of index values (not bytes).
Return a pointer to the u32 index data for sub-mesh submesh of mesh mesh_idx.
Returns null if the mesh uses u16 indices or the indices are out of range.
out_len receives the number of index values (not bytes).