RTX Raytraced Caustics


In this demo @ 1:23 they demonstrate Realtime caustics as feature of RTX, i have been searching for a way to get this effect in my project with no luck at all.
i have all rtx features working properly but i can’t find any option to enable caustics, There is nothing also about caustics in the documentation
Translucent objects just cast raytraced shadows as opaque, and reflective objects doesn’t reflect lights rays to appear on other opaque objects like in the demo

i have UE4.22 official release
Any idea how to get this feature ? is there a special branch that have the caustic feature ?

It’s not in UE4 right now, the raytracing feature is not entirely complete

After some researching i found this, and it is what i suspected, the feature already there but on other branch

The guy who is presenting @16:58 is running UE4.20 and the viewport is on (Ray Traced Lighting) mode

I guess all i need to find out now is the branch name and location and is it public or not !…umination.html


On the other side the Atomic heart demo is built in ue4 and it feature Real Time Caustics unlike (NetEase: justice) demo which use in-house engine

The caustics effect in the video looks more like a light function material applied to a point light source other than raytraced caustics.

You are right, I watched again and i noticed in the atomic heart demo even when RTX off the caustics still on.

But in the first video (siggraph 2018) it’s a RayTraced caustics and it runs in custom branch of UE4 likely to be owned by nvidia,

i checked the code of RTX branch of the gameworks UnrealEngine fork, there is no sign it have such thing as viewport (Ray Traced Lighting) mode
in the viewmode menu…rtViewMenu.cpp

I guess nvidia have another secret repository :rolleyes:

Raytracing caustics is a bit, meh, for it’s uses? It’s relatively expensive, especially as you add more lights. A simple scene on a 2080 with one light takes almost a millisecond for good caustics, just start adding scene complexity and more lights, and suddenly your at a very large fraction of your render time for an effect that most people won’t care if it’s faked.

There’s a presentation on a paper for it in the GDC vault, and I can see it as a timesaver for artists, if it’s only done on the sun and you have a bunch of complex water to do it on (spline based streams with some animation/physics hacks or whatever). But overall there’s better things to spend raytracing and render budget on.