So, turned out after all we need a foreachmapped helper for loops as well... :/ CDDM and EBDM were reasonably simple, but I fought hours with CCGDM (subsurf) to find only a bad working solution (see D478). So I fallback to a code similar to CDDM one. Probably not nice for performances, but loops and subsurf are not matching well... Reviewers: campbellbarton CC: brecht Differential Revision: https://developer.blender.org/D478