Vulkan Mobile backend: Lights don't affect primitive meshes

[mrjustaguy]

Godot version

v4.0.dev.calinou [6d58b96]

System information

Windows 11, Vulkan, Nvidia Quadro K2000 461.92

Issue description

Lights don't work on the Mobile Renderer on non-pre-alpha builds.

This is quite possibly related to the specific GPU architecture, as Kepler GPUs are known to have plenty of issues with DX12 and Vulkan.
I don't have access to different GPU architectures that support Vulkan so I cannot test the theory out.

Do note - Changing shading of the mesh to Lambert and things like that don't fix the lack of lights.

Steps to reproduce

Create a Mesh and try to apply Lights to it.

Minimal reproduction project

Bug.zip

[Calinou]

I can reproduce this on master 2a9dd65 (Linux, GeForce GTX 1080):

This only affects primitive meshes, not imported glTF scenes (level.glb.zip):

Adding a new StandardMaterial3D override fixes the issue:

My guess is that the fallback material is too dark in the mobile renderer.

Vulkan Clustered backend fallback material:

godot/servers/rendering/renderer_rd/forward_clustered/scene_shader_forward_clustered.cpp

Lines 705 to 719 in a5c14bd

	storage->shader_set_code(default_shader, R"(
	// Default 3D material shader (clustered).
	shader_type spatial;
	void vertex() {
	ROUGHNESS = 0.8;
	}
	void fragment() {
	ALBEDO = vec3(0.6);
	ROUGHNESS = 0.8;
	METALLIC = 0.2;
	}
	)");

Vulkan Mobile backend fallback material:

godot/servers/rendering/renderer_rd/forward_mobile/scene_shader_forward_mobile.cpp

Lines 688 to 702 in a5c14bd

	storage->shader_set_code(default_shader, R"(
	// Default 3D material shader (mobile).
	shader_type spatial;
	void vertex() {
	ROUGHNESS = 0.8;
	}
	void fragment() {
	ALBEDO = vec3(0.6);
	ROUGHNESS = 0.8;
	METALLIC = 0.2;
	}
	)");

I can't see any difference between the shaders though.

[Calinou]

Note that this was not fixed by #58628. I tested the commit just before and after, and can confirm the issue is still present in both commits with the MRP linked.

What's strange however is that I can't reproduce this in a brand new project…

[lufog]

@Calinou, I think #58628 fixes the problem, but you need to delete project's .godot folder. Perhaps this data is cached?

v4.0.alpha.custom_build [54a777b] (previous build):

v4.0.alpha.custom_build [039ffda] (build with fix):

[Calinou]

@lufog I see, I guess we can consider this resolved then.