Get Emissive Color as Scene Texture

anonymous_user_c9af2721 · August 26, 2015, 2:47pm

Hi,

For my post processing volume I wish to have access only to the emissive, like the sceneTexture:diffuseColor but with emissiveColor for example. Is there something I missed or anything that should do the trick ?

Thank you,

Juice-Tin · August 5, 2019, 9:06pm

While I’m about 4 years late, throwing this here for anyone else who needs it.

You can use SceneTexture:PostProcessInput0 to get the current scene. Then if you consider that emissive is basically just light that is above 1, you can subtract 1 from that to get the scenes emissive. You may also get some areas that just have bright lights, so you can increase the subtraction to reduce any non-emissives.

In the above example, I’m also turning it white (desaturation) and clamping it to 0-1, so I get a nice black+white mask of where emissive colors are used.

Darkg0re · June 20, 2022, 1:51pm

Thanks a lot for this!

KOCE92 · December 14, 2022, 6:14pm

Thanks for this sadly it stopped working with the Unreal Engine 5.0.1 version hope Epic will add this as a render pass in future

KOCE92 · December 20, 2022, 3:21pm

Found what was the problem just change the blendable location to “Before Tonemapping” and it will work.

monodrobe · January 6, 2024, 10:23am

Woots!, Thanks for this. Helped me figure out how to add bloom back into a post process.
PostProcessInput0, subtract 1, max 0 ( to get rid of any negative values), add to final result

Been scratching my head on solving this for a while. Much thanks