Vulkan: WorldEnvironment Energy does not scale sky-contributed ambient lighting (unlike 3.x)

[Calinou]

Godot version

4.0.dev (489f11e)

System information

Fedora 34, GeForce GTX 1080 (NVIDIA 470.74)

Issue description

Unlike 3.x, WorldEnvironment Energy in master does not scale sky-contributed ambient lighting. Decreasing Sky Contribution will darken ambient lighting as expected (like in 3.x), but it's still not affected by an Energy greater than 1.0 or lower than 1.0.

This may have been a design decision, but in this case, it should be documented in the WorldEnvironment class reference.

adjust-sky-contribution-then-energy.mp4

In contrast, a non-default energy value will brighten or darken sky-contributed lighting (regardless of how much light is being contributed):

adjust-sky-contribution-then-energy-3.x.mp4

Steps to reproduce

• Add a MeshInstance3D node where ambient lighting can be seen.
• Add a DirectionalLight3D node then hide it to prevent the default light from influencing results.
• Add a WorldEnvironment node with a PanoramaSkyMaterial.
• Decrease Ambient Light Energy and notice it has no effect unless a custom (non-black) ambient color is used.

Minimal reproduction project

test_environment_sky_contribution_master.zip