Vulkan: SDFGI and VoxelGI are only combined correctly if VoxelGI is enabled *after* SDFGI, not before

[Calinou]

Godot version

4.0.dev (5efe80f)

System information

Fedora 34, GeForce GTX 1080 (NVIDIA 470.74)

Issue description

The Vulkan renderer makes it possible to combine both VoxelGI and SDFGI to maximize GI quality at the cost of performance. However, this only works correctly if VoxelGI is enabled after SDFGI, not before.

voxelgi-sdfgi-combine.mp4

Steps to reproduce

• Enable SDFGI in WorldEnvironment.
• Then enable VoxelGI by making the node visible. Notice the correct appearance with VoxelGI being overlaid on top of SDFGI.
• Disable SDFGI in WorldEnvironment.
• Enable SDFGI in WorldEnvironment again. Notice the broken rendering with the white outline (similar to Vulkan: VoxelGI and SDFGI rendering exhibits a visible outline between surfaces and the sky #54978).

Minimal reproduction project

test_gi_texture.zip