Vulkan: VoxelGI doesn't represent environment lighting in reflections (unlike SDFGI)

[Calinou]

Godot version

4.0.dev (4651b2a)

System information

Fedora 34, GeForce GTX 1080 (NVIDIA 470.74)

Issue description

Unlike SDFGI, VoxelGI doesn't represent environment lighting in reflections even if Use Two Bounces is enabled in VoxelGIData and a high propagation value is used. This results in VoxelGI reflections looking too dark on metallic materials.

This may be linked to #35200 (and #35800).

A more extreme example with a bright green ambient color, ambient energy set to 16.0 and Sky Contribution set to 0.0:

VoxelGI

DirectionalLight visible

DirectionalLight hidden (only environment lighting is used)

SDFGI

SDFGI's Bounce Feedback is set to 1.0 to ensure correct display of reflections, as per #49836.

DirectionalLight visible

DirectionalLight hidden (only environment lighting is used)

Steps to reproduce

• Add a VoxelGI node and a mesh with Static bake mode.
• Add another mesh with a fully reflective material (roughness = 0, metallic = 1). A MeshInstance3D with a SphereMesh works well for this purpose.
• Select the VoxelGI node and click Bake at the top of the 3D editor viewport.

Minimal reproduction project

global_illumination_1.zip