Thanks for your tips, DaBroozar!

Well, it's not that normals are inverted: actually, this 'belt' is a double faced mesh: it was duplicated, flipped and weld together, like if it was a piece of cloth.

I had used this method before to create 'double sided geometry'. But it seems it means trouble. Do you think there's another way to create double sided triangles?


I also made another kind of belt - a solid one, not so thin.. but now and then I get the shadows problem. It seems that there are other 'rules' to apply to the model, besides 'open meshes'. For starters, internal patches also give me shadow problems.

Unfortunately I don't have 3D max or C4D. For now, it's just a trial and error process..


EDIT: Reviewing the manual... "Stencil buffer shadows can only be cast by nontransparent models consisting of closed meshes with no holes or intersections..."

Maybe these intersections are the problem (!) I'll work on this. THanks!