Maya: Normals - a game question for film production

EdgeIcon

Hello everyone. 

I have an interesting dilemma that im trying to sort out that typically isnt seen too often in the film production world but is all about handling normals across multiple objects. 

we have a mesh that is too large to be rigged as one object so we are detaching the edges on limbs and digits of the hand. 

When we detach the edge, the normals create a seem. 
The mesh needs to be in "3-mode"  ( smoothed )  which seems to keep the seam no matter what kinds of smoothing or averaging we do on the normals. 
I am curious if there is a good method to preserve proper normals while a mesh is smoothed after being detached. 

This one is oddly specific but i appreciate any insight. 

thanks!

throttlekitty

For normals on a regular model, you'd Lock the normals prior to separating to prevent that seam across meshes. You can always use Transfer Attributes to correct a separated model from the original "full" copy of the model. Here's a simple example of a sphere with a separated selection on the right:




For maintaining subdivision boundaries across splits... I'm not sure that's 100% doable. The best option is to pick smart places to split at. Here's what you're up against: (note that I needed to set the smooth mesh controls> vertex boundary to "sharp edges" only to avoid sharp corners here)


The only solution that I'm aware of would be to extend the splits so they overlap, allowing the subdivision to flow properly. So instead of a 3x3 inner section, I'd use 4x4, and also include the outer ring of the original 3x3 in the main sphere. Then you'd make the set of overlapping faces invisible, but YMMV when it comes to how your renderer would handle masked faces, you might get unwanted shadows.

I've got some distant memory that opensubdiv supported something like this, but I can't find anything at the moment. Or maybe it's in the spec but maya doesn't support it.

quick edit because coffee: I forgot to mention that as far as I am aware, when in "3 mode" or smooth mesh preview, the normals are entirely implicit from the geometry as it's smoothed. I don't think you can explicitly define them. If the "extended boundaries" trick doesn't work, you may have to look into converting into a real mesh and locking the normals there. And if it's super heavy, RAM-wise, you might want to look into using proxies at that point.