Learning to model with Blender. Trying to modify an existing model, at some point I "wrinkled" it. I'm suspicious about some custom code (I'm developing a Blender plugin to export/import models from a game) to save and reload normals, but the case is I have this model now and I want to know what's going on so I can fix it.
With autosmooth turned off:
With autosmooth on:
What causes this? How can I fix it so when autosmooth is enabled, it looks like the figure on top?