Why Edit Poly Modifiers Breaks Smoothing Groups?

jamilahmmed

I imported this model into 3ds max. applying edit poly modifiers breaks the smoothing groups in it. How do I preserve smoothing group while applying the modifiers. 

poopipe

it's usually because the imported model has explicit normals defined. it's tricky to preserve that

gnoop

it's one of the reasons I prefer Blender.  You can edit something with explicit normal's   and it's only breaks them in faces adjacent  to your edited area .   Plus you could have the data transfer modifier that  fixes it on the fly.    

While in MAx you need expensive Ornatix   to do so. 

I once wasted a  weekend trying to do normal transfer  with MCG  in MAx.  Haven't been even close to something working. 

Why  attribute transfer is still  not in MAx . Should be there years ago already.

sprunghunt

 this is just a guess but what happens if you put a "edit normals" modifier on the model before the edit poly?

poopipe

Turn to mesh/poly and edit normals  will sort the data out but it doesn't always preserve everything. 

When you bring a model in from Maya or something else that doesn't support smoothing groups discrepancies are inevitable. 

I remember some discussion on the matter on here a few years ago and i don't think anyone came up with a reliable algorithm for translating between smoothing groups and edge definitions - it's certainly beyond me

Swordslayer

If you switch to max 2021 or newer, explicit normals will be preserved. If you prefer smoothing groups over explicit normals (for example if you plan on modifying the mesh and want more freedom), check "Smoothing groups" when importing the fbx - this will try to convert explicit normals to SGs.