Can't turn off the global illumination with the source light

I want to be able to turn off my sunlight at runtime, but I can’t make the global illumination disapear.

If the level is built with the sunlight on, the GI is calculated and it remains visible even if the sunlight is visible false or zero intensity.

If the level is built with the sunlight off, the GI is never built, never visible.

How can I turn off a light at runtime including its global illumation?

Hi methusalah,

When you’re using a stationary or static light that has baked in GI will not be disabled since it’s precomputed. One thing you could do is use a Post Process Volume in the area need or set as Unbound and have it use a timeline in a Blueprint so that you can adjust the fade of the GI over time as the light intensity shifts. You don’t have to use a timeline and could simply just set the Global Illumination Indirect Lighting Intensity to 0 via the Post Process Volume settings.

-Tim

Hi and thanks for your answer. I understand that I can’t activate and desactivate my gloabal illumination at runtime, because it is build once and for all.

But isn’t it strange to calculate the GI for stationnay lights? The purpose of these lights is to be able to change their intensity and color at runtime. What’s the point if the GI they generate isn’t dynamic?

But isn’t it strange to calculate the
GI for stationnay lights? The purpose
of these lights is to be able to
change their intensity and color at
runtime. What’s the point if the GI
they generate isn’t dynamic?

This is covered in the first paragraph of the documentation here:
https://docs.unrealengine.com/latest/INT/Engine/Rendering/LightingAndShadows/LightMobility/StationaryLights/

Only the direct light portion of the stationary light will be affected with the any changes to intensity or color.

Using the Post Process Volume is the way to adjust the intensity at runtime for these lights.