Updated on 14th Mar 2021

Global Illumination

The Simple Light Painter offers localized Global Illumination (GI) on all Light Painters. This allows you to color Areas of your Level with the average Color of the Environment, including Objects with Emissive Materials.
Please note that the SLP currently does not offer an Editor preview of GI and is only visible in runtime.

GI Setup

Before you can use localized Global Illumination on the Light Painters, you will need to add a Component to your Game Mode. The "BP_SLP_GIManager" will capture and control the entire GI System during runtime.

After you added the Component to your Game Mode, place a Light Painter into your Scene and set "Enable Global Illumination" to true. This should be everything you need to do.

Performance

The GI Manager and the Light Painters will try their best to keep your Game smooth, but you should still be aware of how it works and what you should not do.

GI Update Times

There are 3 Variables you can control on how the GI Updates do their work. These can be changed on every Light Painter.

  • GI Update Time
    • Controls the Delay between Capture Updates in Seconds. Each Update will try to capture a Scene Cube for each GI Location. Short delays are not recommended in most cases.
  • GI Transition Time
    • Controls the Fade Duration of the Light Color during GI Updates.
  • GI Culled Update Time
    • Controls the Delay between Updates while the Light is not being rendered on the scene. This value should be higher than the "GI Update Time"!

How the GI Capture works

This Global Illumination System generates the Average Color of all the Objects that are being rendered in a Scene Capture Cube. These Colors are then painted onto 2 Render Targets, which are responsible for Light Transitions and the Currently displayed Light Color. In other words, your GI Light Colors are limited to a Texture. This mostly limits the Amount of GI enabled Light Painters you can have in a scene at the same time.

But do not worry, you should never experience the Limit, because it currently supports up to 8192 different GI enabled Light Painters. The Playground Map has a Performance Test where 1000 GI enabled Light Painters are being placed into the Level. You should not do that in your projects, but it does works.