With the introduction of per-face material and its announcement in V6 new features we have realized that it may be a plan to release it as-is, which seems like a good idea that is not fully implemented, possibly creating issues down the road. Sure, it works nice on a simple model, but the practical use on more complex models can be problematic without some fixes or additions:
We need to be able to explode the polysurfaces and have the sub-faces retain the individual materials
We need to be able to explode polysurfaces by-material (basically separate the pieces based on custom materials assigned). Also ability to select sub-surfaces ByMaterial.
Currently when the custom material face is selected, the Properties panel still shows the general object material with no info/ability to edit the selected custom sub-material. (Only the case if object’s material is ByLayer, if ByObject, then it shows it fine)
when changing the entire object material, there should be an option what to do with faces that have custom material assigned: either keep them unaffected or change all subsurfaces to new material - currently Rhino resets all faces to new material.
Boolean operations randomly change the per-face material assignments. They should stay unaffected. Same goes for Split command. Didn’t test it thoroughly but the idea should be the objects are still editable with all commands but keeping the material assignments.
Please consider these before releasing the new feature that can cause problems, especially with working with someone else’s models that use that feature or trying to export to other applications and trying to retain the material assignments.