The abnormal dark areas of the ribbon

[Happy0Ending]

hello everyone，
this is my PG:Ribbon Examples | Babylon.js Playground

The created ribbon seems to have uneven lighting
What should I do to make him look like a cube?

I will be very grateful for everyone’s help

[Cedric]

This is related to normals

Babylon.js docs

With faceted normals, you’ll get this: https://playground.babylonjs.com/#F6JW5W#2138

[Happy0Ending]

Perfect