Vulkan: Shadows in VoxelGI voxel scene that do not appear in the rendered scene

[ricky-daniel13]

Godot version

4.1.3, 4.2.6

System information

Godot v4.2.beta6 - Windows 10.0.19045 - Vulkan (Forward+) - dedicated NVIDIA GeForce GTX 1650 (NVIDIA; 31.0.15.3734) - AMD Ryzen 3 2200G with Radeon Vega Graphics (4 Threads)

Issue description

While using VoxelGI for indirect lighting, the voxel representation of the scene renders a shadow that isn't actually there in the real rendered scene. These non-existing shadows then lead to innaccurate global Illumination. This happens with both Spotlights and Omnilights. When shadow casting is turned off for the light, the non-existing shadows disappear (Along with, obviously all shadows).

Steps to reproduce

• Open the scene "test_scene.tscn"
• On the "Display Advanced..." options of the preview camera, click on "VoxelGI Lighting"
• See the shadow being rendered in the voxel world that is not happening in the normal world.
• Select the "Spotlight3D"
• Disable the shadow casting option
• See the glitched shadow disappear in the voxel world

Minimal reproduction project

ReproVoxelGI.zip

[bitsawer]

Looks like VoxelGI is very sensitive / buggy if its size is not an even box, possibly related to #62930. Simply setting VoxelGI size to 20x20x20 in the test project and rebaking seems to fix the main issue. Setting the size even a little uneven like 20x20.1x20 changes the visuals quite a lot.

[ricky-daniel13]

Thanks for looking into it. Seems like voxelization is very sensitive to the offset of the transform too.