Creating and printing Split Normals in Python

Question

I created custom split normals, they show up in the viewport, but how can I get a list of them in python?

import bpy

mesh = bpy.context.object.data

mesh.use_auto_smooth = True
mesh.normals_split_custom_set( [(1, 1, 0) for v in mesh.loops] )

for l in mesh.loops:
    print(l.normal)

The code above just prints out (0.0,0.0,0.0) vectors, so split normals are probably stored somewhere else.

Answer 1

• You need to call mesh.calc_normals_split() once before you can access the loop.normals. Otherwise they will all be zero, as you found out.
• In addition to use_auto_smooth needing to be on, polys need to be smooth-shaded (poly.use_smooth = True) to use the custom normals.
• Make sure the vectors you pass to split_custom_set are really normalized or you will get weird results.