NvRTX Caustic Branch 4.27 build/rebuilt error

Hello fellow devs and Nvidia team,
I’m Deb and I am huge fan of NvRTX caustic branch. I with my team members trying to create a open world action rpg and a tech based PvP/PvE like tribe ascend we want to create breath taking visual effects using the mesh caustic, dlss and RTXGI. We do not had any issue with 4.26.2 branch of it but then we switched to 4.27.2 as it had Niagara fluid simulation but as we are proceeding, making a simple c++ class and changing its code very little causing a weird bug: when we clicking build in VS, the complier just rebuilding the whole engine. This is happening if in a session we click build more than 3-4 times and also we get some common syntax error.

Another isssue is that in NON-RTX ambient occlusion mode, AO of the material is not working, ie if we put an AO map in Material, it is not displaying on AO channel.

We thought to change to NvRTX UE5 but we are not sure if that branch have caustic as its not mentioned in description. We are waiting for that for UE5. Can you confirm if the caustic features will be implemented in ue5 rtx branch??

We are looking forward to hearing from you. Quick response is highly appreciated and respected.

Hi @t.g.db.letsmakelifelitalw , thank you for your interest in the NVRTX branch!

This might be a bit short notice, but today there will be an RTX and UE5 webinar, where we will also mention the various features of the NVRTX branch, also followed by a Q&A. Check the announcement for the details.

But since I am also not 100% sure about the Caustics part, I will ask for clarification and post the reply here.

@MarkusHoHo you have not told me about RTX caustic for ue 5. Are those features going to get abandoned just like nvidia gameworks??

Hi there,

I reached out to Engineering and hope to hear from them soon.

Thanks for your patience!

Hello Deb! The plan has been to reintroduce RT Caustics into UE5 with the upcoming release of 5.1. My understanding is Epic is making some changes in how translucency is handled in 5.1, and implementing caustics starting with that version will make the most sense for the development team. I can’t give a firm release date for that version of NVRTX, but typically we release the code within a matter of weeks of when Epic finalizes their code. This is because we need some time to do some internal testing, QA of the branch etc before releasing it to you.

Hope that helps! -Richard


Hi @rcowgill, does this mean that in the upcoming 5.1 release the original 4.27 caustics demo can be run without the hassle of compiling and runs just straight out of the box? That be awesome!.

PS, in terms of hardware requirements, I assume a RTX 20 series or better is still required for this to run smooth?

Hey @rcowgill,
Is there any update on the Caustics branch for Unreal 5.1?
I haven’t seen the NvRTX_Caustics branch get updated on the github yet so I hope there aren’t major issues with the new Unreal builds preventing the previous way from working.
I’d like to have caustics for Unreal 5.1 as it would be a great addition for cinematic rendering. Since it would pull some shots to the next level together with the lumen lighting.

I mostly hope it is still in development and can look forward to a new version eventually.

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Hello, @W0lf NvRTX Caustics 5.1 is out : https://github.com/NvRTX/UnrealEngine/tree/NvRTX_Caustics-5.1

This branch offers entire solution to draw proper translucency including: reflection, refraction, absoption, order independent, caustics, and RT DOF. Please let me know your feedback if you encountered with some issues.


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Thank you @jackwang1, this is great news. I am looking forward to test this out as soon as I will have a spare moment. We have integrated UE caustics in our 3D rendering and post production pipeline and we were looking forward to an updated UE 5.1 version.