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eidosmontreal / unreal-vdb

This repo is a non-official Unreal plugin that can read OpenVDB and NanoVDB files in Unreal.
Apache License 2.0
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Fire as light source #83

Closed xXchrizzoXx closed 1 year ago

xXchrizzoXx commented 1 year ago

Hey thilamb,

thank you very much for the plug-in! It also works with houdini <3 A vdb sequence with fire for example doesn't emit light on its own so that it illuminates its surroundings, right? - Or am I doing something wrong?

Greetings, Chrizzo

Andrej730 commented 1 year ago

@xXchrizzoXx hi! Had similar question in #38 Not sure if it's not emitting any light at all but I remember that it doesn't emit color. There is hope here that it might work at point in the future - https://github.com/EpicGames/UnrealEngine/pull/10344

BUT in this plugin there is BP_VdbToVolumetricClouds that can help you render your VDB to Volume Texture and then you can render this texture with unreal Volumetric Clouds as a cloud. Volumetric Clouds are already integrated in Unreal so there may be some opportunity to make them glow with Temperature/Flames VDB pass in the Volumetric Cloud shader (I've described related process here - https://github.com/eidosmontreal/unreal-vdb/issues/81#issuecomment-1541505732)

image image

thilamb commented 1 year ago

Hi Chrizzo, thanks for the kind words !

I'm not currently doing anything special to make Fire illuminate the rest of the environment but I recently noticed that the Lumen GI probes do capture the emissive Fire emission, cf my Twitter post here.

It's probably going to be subtle in a fully illuminated scene but it worked in my little experiment.

FYI this won't work with the Pathtracer though, because it doesn't use Lumen.

Cheers

xXchrizzoXx commented 1 year ago

Thank you guys very much for the quick and comprehensive answers! <3

Okay, I will look more into why it's not working on my end. My scene is pretty dark, but maybe the fire is to small to emit enough light: image

Cheers Andrey730 and thilamb

thilamb commented 1 year ago

Lumen needs large sources of emissive to take them into account indeed ! The larger the better but of course it's not always possible. Good luck with this, would be happy to see your results if you can make it work.

xXchrizzoXx commented 1 year ago

Thank you! Sure, it's a personal project so no NDA or something :D

xXchrizzoXx commented 1 year ago

Update, it seams to be a lumen issue. In the next days I try to make a gif which shows it.