Let’s say I’ve disabled Lumen and all other global illuminations. Does sky lights get baked when I bake for lighting?
If you set their movability to Static and disable the Force No Precomputed Lightning in world settings, then Yes it will be baked.
I am aware of this. But, how do I make sure it’s baked?
For static mobility, it is baked for sure if you allow static lighting in your project (Allow static lighting in Rendering settings, and disabling Force No Precomputed Lighting in world settings). You can check by comparing the difference between two reference images of the same scene: one with the sky light, and one without. Clearly you’ll see the difference (you can try to only show Diffuse+Global Illumination in “Lighting Component” show flags)
For stationary mobility, only the sky occlusion is baked (shadowing for enclosed parts of the level), the ambient lighting itself is dynamic.
Bounce lighting will also be baked for stationary skylights unless it is set to 0 bounces in lightmass settings.
That’s what I thought also, until I did a test to be sure.
Just create a simple scene with flat red ground and a white cube above ground (100 or 200cm), with only one stationary skylight (with a basic blueish cubemap), and no other light.
Bake.
After baking, the cube will have the color of the skylight, without any apparent color bleeding from the red ground to the bottom of the cube. This is a first indication there is no GI/bounced light baked.
Then, if you hide the skylight actor, to hide the dynamic ambient lighting from the skylight. Everything gets black (nothing have been baked in the lightmap).
If you look at the lightmaps in world settings, they are indeed fully black in that case. There is Sky Occlusion maps, but this is for the sky occlusion only.
Now, if you change the light from stationary to static and bake, you’ll see the color bleeding of the ground on the bottom of the cube. So GI/bounced light is baked for static skylight, but not for stationary.
To put this into pictures :
Static Skylight only-scene (slightly blue/gray), with pink ground and white mesh on top: you can see the color bleeding/bounced light
Stationary skylight: no bounced light (lightmaps are fully black)
NB: all of this is without Lumen of course
Then it is a bug specific to recent versions of the editor, which is not surprising as lightmap support is falling apart in Unreal. For what its worth, works in GPU lightmass:
So it must be a bug specific to CPU lightmass (as opposed to being an issue with the shader display), as it did work (with CPU) all through UE4 and much of UE5. Personally I’m of the opinion that stationary skylights SHOULD only bake shadows, so I see this as mostly a non-issue but it’s definitely a regression (who knows… maybe someone actually wants this)
Yes, that’s probable the case. In particular if it is inconsistent between CPU and GPU lightmass.
Too bad Lightmass is getting forgotten…