BakedLightmap always bakes direct light shadows (for fully baked lights), even for lights that have shadows disabled

[Calinou]

master version of this issue: #56611

Godot version

3.4.2.stable, 3.x (0b54b3d)

System information

Fedora 34, GeForce GTX 1080 (NVIDIA 495.46)

Issue description

BakedLightmap (CPU lightmapper) always bakes direct light shadows, even for lights that have shadows disabled. I don't know whether this is a bug or a design decision, but this should either be fixed or documented (both in the class reference and Baked lightmaps page).

Orange lights have shadows disabled, blue lights have shadows enabled. Lights on the left are OmniLights, lights on the right are SpotLights.

Fully baked lighting

Real-time lighting

Steps to reproduce

• Import a glTF scene. Set the light bake mode to Gen Lightmaps in the Import dock and click Reimport.
• Add a BakedLightmap node and configure its extents to fit the imported scene.
• Add an OmniLight node with shadows disabled. Add a second OmniLight node with shadows enabled. Move them so you can clearly see the difference between shadows being enabled and not. Set both lights' bake mode to All (Direct + Indirect).
• Repeat the above steps with two SpotLight nodes.
• Bake lightmaps. Look at the result; both lights will cast shadows.

Minimal reproduction project

test_baked_lightmap_no_shadows.zip