Mesh triangles have weird lighting

Unity Engine
, ,
1

I need to create three dimensional objects from two dimensional pointlists (so the input for my example here is a triangle pointlist) and want to use meshes. I was able to create the mesh but there is one problem:
The triangles on the sides have weird lighting behaviour (e.g. at the top): The areas should look the same especially as it is partly the same triangle. But as you can see the top side has two different bright zones. Rotating the objects changes the lighting behaviour btw.

6137919--669681--upload_2020-7-27_18-40-21.png

What did not work:

  • Changing shader or any property of the material
  • Trying other UV coordinates (although I think the given are correct)
  • Disabling directional lighting (the transitions get softer…)
  • Calling mesh.RecalculateNormals(), mesh.RecalculateTangents() and mesh.RecalculateBounds() are not doing the work

Maybe this could be interesting:
mesh.vertices
6137919--669624--upload_2020-7-27_18-22-36.png
mesh.triangles
6137919--669633--upload_2020-7-27_18-24-11.png
mesh.uv
6137919--669642--upload_2020-7-27_18-24-44.png

I’m grateful for any help!

2

You could try mesh.RecalculateNormals(), mesh.RecalculateTangents()

3

I found an article explaining exactly my problem (A short explanation about custom vertex normals (tutorial) — polycount). The normales for the vertices created by mesh.RecalculateNormals() are not correct because they represent an average of all sides. So to have correct lighting, I need to split each vertex into 3 vertices with each another normal so that each area has its own correct normals.

Edit: I solved this by creating an own mesh for each side, doing mesh.RecalculateNormals() for each and then combining the meshes with CombineInstance.