probably many of you noticed that working with multiple shaders on one mesh can be very problematic, expecially if some Mesh Extract or Mesh Separate is required for further editing.
Problem is that if you have one single mesh (merge vertex doesn’t matter), and if you try to separate the mesh by materials, maya goes crazy and mixes the shaders in a random way for random polygons of the mesh.
Using different shaders in one mesh is a common workflow in many other softwares, but in Maya it’s very problematic, and it requires to do more steps just to workaround one simple thing.
Too bad that even at sp3 nobody seems to care to fix this bug natively, but hey, let’s hope for 2018.
Anyway, the fix
I found this script from 2012 and it still works great: https://gist.github.com/mstevenson/4145716
Can’t believe that I finally found a fix to something that bugs me so much about Maya, many thanks to the author Michael Stevenson.