Vulkan: Per-vertex shading not working

[AlzoPalzo]

Godot version:
v4.0.dev.calinou.e16729a8c

OS/device including version:
Windows 10, GTX 1070, Vulkan

Issue description:
In Godot 3.2 I used Tree models with their normals edited in blender in tandem with per vertex shading to create smoothly shaded trees. In Godot 4.0, with vulkan backend switching the shading between per vertex and per pixel has no effect on the tree models

Examples of the expected result are shown below where the trees on the left are shaded per pixel and the trees on the right are shaded per vertex.

Steps to reproduce:
Add a directional Light or other lights to the models and in the material turn on the per vertex shading flag(3.2) or switch shading to per vertex(4.0)

Minimal reproduction project:

LowPolyTrees.zip

[r0-che]

vertex shading still does not work in 4.0

godot 3.5, vertex shading on the left

godot 4.0 beta, vertex shading on the left aswell

[AnalogFeelings]

It seems it's also happening in the gl_compatibility and mobile renderers. I tried using the shaders from godot-psx on all 3 renderers and none of them have vertex lighting, only pixel lighting.

(Windows 11, RTX 2060, Godot 4.0 Beta 12)

[zCubed3]

I've noticed 2 things regarding vertex lighting in 4.X, I hope it can be of help to someone more talented with graphics programming. (I'll note these are just my observations, I know nothing about how Godot's rendering pipeline works)

1. Looking at 3.X, I can see that scene.glsl contains the USE_VERTEX_LIGHTING flag. While in the master branch, scene.glsl (and its equivalents) are completely missing the flag.
2. It also appears that from the C++ side of things that USE_VERTEX_LIGHTING is never set anymore. The flag doesn't exist anymore in material.h either?

[clayjohn]

I've noticed 2 things regarding vertex lighting in 4.X, I hope it can be of help to someone more talented with graphics programming. (I'll note these are just my observations, I know nothing about how Godot's rendering pipeline works)

1. Looking at 3.X, I can see that scene.glsl contains the USE_VERTEX_LIGHTING flag. While in the master branch, scene.glsl (and its equivalents) are completely missing the flag.
2. It also appears that from the C++ side of things that USE_VERTEX_LIGHTING is never set anymore. The flag doesn't exist anymore in material.h either?

Vertex lighting hasn't been re implemented yet in 4.x

[zCubed3]

👍 Thanks, good to know.