LightmapGI does not take transparency into account when baking shadows.

[EzraT]

Godot version

v4.0.3.stable - v4.3.dev3

System information

Godot v4.3.dev3 - Fedora Linux 39 (KDE Plasma) - Wayland - Vulkan (Forward+) - dedicated AMD Radeon RX 580 Series (RADV POLARIS10) () - Intel(R) Core(TM) i7-3770K CPU @ 3.50GHz (8 Threads)

Issue description

As the title says, LightmapGI bakes shadows for objects with transparent materials as if they are 100% opaque.
I tried baking with every transparency mode possible, Alpha, Scissor, Hashed, Depth Prepass, none of it makes a difference.
This worked fine in Godot 3, so there is definitely a bug here.

Godot 3:

Godot 4:

Steps to reproduce

1. Download the included MRP's, both Godot 3 and Godot 4 versions are provided.
2. Load up the projects and compare results.

Minimal reproduction project

mrps.zip

[EzraT]

Retested in v4.2.beta4.official, still present.

[Calinou]

I can still reproduce this on 4.3.dev cae7599 (Linux, GeForce RTX 4090 with NVIDIA 545.29.06):

[passivestar]

Encountered this too, 4.2.1, macOS 14.4.0 - Vulkan (Forward+) - Apple M1 Max