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Light Function

I’m looking for an alternative to emissive materials for shaping light projection, as UE4 has removed emissive material contribution to Lightmass.

The first obvious choice is Light Functions, but the documentation currently has only a short paragraph and an image.

Can anyone with experience with Light Functions share their experiences? Are they suitable for soft diffuse illumination (strip lights, stained glass windows, neon signs), and can they be baked into Lightmass? Are they restricted to specific Light types? Or, is there a better way to get emissive material stand-ins?

To answer some of my own questions.

-Light Functions can’t be baked into Lightmass.
-There’s no UV scale in the Light’s Light Function panel (this would be useful on spotlights to clamp on a portion of a mat texture)
-They read RGB textures as single channel luminosity maps, so i.e. stained glass windows are out.

Where to next?

I think this is what your looking for, I way to fake emissive lighting? Sorry the meaning of shaping light protection is a little over my head :stuck_out_tongue:

Sadly not - that’s for dynamic emmission; the illumination appears in reflections, but it doesn’t contribute to lightmapped diffuse (i.e. they’re not really casting light anymore).

They took this off the feature set because it looks odd when you have characters walking next to a emissive texture which doesn’t actually light up the character.

I have no characters in my games, and besides which I think it’s up to the artist to decide what does and doesn’t look right for what they’re trying to do. Hand-holding. Go figure :slight_smile:

Funny. When I opened “Shooter Game” from the Marketplace I was surprised how there were some long green lights in some interior parts with singular static point lights placed at equal distances between them along the light source. My first thought was:“Why not use emissive in the material?”. Now it’s clear.:slight_smile: