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RTX Features

PostPosted: Mon Sep 02, 2019 9:33 am
by Phoebe Baddlebury
I was playing around with the Doom Ray Tracing source-port last night. It seems to be a modified version of GZdoom 4.2.0.
Is this going to be something that is officially implemented someday?

Re: RTX Features

PostPosted: Mon Sep 02, 2019 10:21 am
by drfrag
Doom RTX? It was a fake.
Upon further investigations, it appears that this mod is indeed based on Doom Remake 4, and does not use real-time ray tracing. This mod uses GZDoom which does not feature any ray tracing capabilities. This very same mod was uploaded on ModDB back in June 2019 and was taken down by its moderators. However, this time the ModDB moderators were not quick enough to delete this new entry. So yeah, while this mod improves visuals, it basically borrows a lot of stuff from other mods. Not only that, but it does not feature any ray tracing effects. Bummer.

https://www.dsogaming.com/news/doom-rtx ... ulkan-api/

Re: RTX Features

PostPosted: Wed Sep 04, 2019 5:30 pm
by Trusty McLegit
I know he was referencing a specific implementation, but since it's been brought up, are there any plans to implement Ray tracing in the nearish future?

Re: RTX Features

PostPosted: Fri Sep 06, 2019 1:21 am
by Kinsie
Trusty McLegit wrote:I know he was referencing a specific implementation, but since it's been brought up, are there any plans to implement Ray tracing in the nearish future?
I don't think the developers (or indeed, most of the people running GZDoom) have any GPUs that support such a thing yet.

Re: RTX Features

PostPosted: Fri Sep 06, 2019 1:24 am
by Graf Zahl
dpJudas does have an RTX card but I don't because right now it doesn't offer anything of value to me.

Re: RTX Features

PostPosted: Fri Sep 06, 2019 4:33 am
by dpJudas
Yep, I have a RTX card. The big showstopper is that the vulkan RTX API wants an acceleration structure (a polygon soup) uploaded and that's not really how GZDoom works.

The shadowmaps sort of already creates one, but for RTX to work it needs the sector heights included which complicates matters a lot.

Re: RTX Features

PostPosted: Fri Sep 06, 2019 5:30 am
by Graf Zahl
What precisely does it want to have? If you can give more detail, maybe a solution can be found.

Re: RTX Features

PostPosted: Fri Sep 06, 2019 6:08 am
by dpJudas
It wants a VkGeometryNV structure, which is essentially a list of triangles. Or it can use an AABB tree with a shader that can do the ray trace hit within an AABB node.

A list of triangles is problematic as height changes in a sector changes those triangles, and the custom shader solution has the problem it needs the sectors, lines and BSP tree uploaded as storage buffers.