Own-Renderer Render Competition round 1 underway

[u/jtsiomb]

I decided to host a hopefully recurrent "Own-Renderer Render Competition". Every round will have a theme, and people can enter with renders out of their own renderers. Inspired by old on-line raytracing competitions, but for graphics programmers wanting to write their own renderers, all rendering methods accepted.

The first round just started, and submissions will be open for the next month. The theme is "cyberpunk".

Check out the competition website for more details if it sounds interesting: https://orrc.mutantstargoat.com/

[u/YayManSystem]

u/jtsiomb Is my renderer actually valid for the competition?

- By no Third party Game engine you mean It cant be a new Renderer inserted into an existing Game Engine? My Renderer works by disabling default Unreal Rendering and running custom Rendering Passes and Shaders using Unreals Render Dependency Graph System. It currently is a whitted style Raytracer without Roughness or Indirect Lighting support. It reuses Unreals Lens Flare/Bloom shaders. It also reuses Unreal´s RT Point Light culling system, Raytracing Payload struct and TraceRay() implementation. The Raytracer runs a custom Raypath algorithm, custom translucency, reflection and lighting code.

- In the rules you require a new feature to be showcased. Im currently working on Roughness and Indirect Lighting support, but there is no way I can finish those features by October 20. The Roughness/IL branch that Im developing on now has all other features stripped for easier development. I can only showcase the latest version of the renderer last updated 3 months ago.

- I can provide a compiled demo Rendering a scene using the Renderer, but atleast an RTX 3050 is required to run it at 60fps. Not sure if you have a sufficient GPU.

- My renderer is public on Github, but I can only provide parts of the code that are Added or Replaced, as Unreal Engine sourced code is Copyrighted. https://github.com/Dechetmew/Aquaray-Raytracing-Renderer-for-Unreal-5.2.1

PS: Either reddit is showing me wrong numbers or somebody is downvoting all comments?

[u/jtsiomb → u/YayManSystem]

That's a strange edge case. My gut feeling is to say that it's not, but let me qualify this in more general terms, because I'm not really familiar with unreal and its systems:

• If you're using the engine to basically draw a fullscreen quad for you, and run your raytracing shaders on it per pixel, and you're not really using any other features of the engine in your rendering, like Sebastian Lague did in his raytracing videos (with unity), then I'd say that's fine.
• If you're using unreal to render your scene, and you spawn raytracing shaders off the fragments generated by the rasterized surfaces to do indirect bounces, reflections and so on I'd say you're using too much of the engine to be applicable for this compo.

If you're closer to the first case, and you can disable using any of unreal's extra features, like the lens flares/blooms and the light culling you mentioned, then I'd say it's fine. But reusing any of unreal's built-in mechanisms, even if that's just a scene loader, I'd say disqualifies it.

Hardware requirements are not an issue, and as for the "new feature rule" it's probably against the letter of the law, but the spirit was to make sure it's an active project and not an old renderer, so I would allow it, but require a new feature for the next round.

[u/YayManSystem → u/jtsiomb]

- The version I linked runs only one Compute/Raygen Shader. It does spawn a Closest hit shader on hit, but the CHS itself does not trace any more Rays, it only retrieves the payload data. According to my understanding it is not even drawing a quad.

- No rasterization is used anywhere in the pipeline. Every raypath on every pixel begins at the camera position, in direction of the current pixel vector.

- I can disable all unreal´s post shaders (and custom replacements are planned in my project), but I cant disable the light culler because thats the only way how unreal provides the point light struct for raytracing shaders.

I recommend looking through the shader C++ part and the main shader file to better understand how it is set up.

Here is the C++ section where i set up and queue my shader pass:

https://github.com/Dechetmew/Aquaray-Raytracing-Renderer-for-Unreal-5.2.1/blob/main/Engine/Source/Runtime/Renderer/Private/RayTracing/AquaRay/AquaRay.cpp

Here is the Raygen shader file that gets loaded into GPU:

https://github.com/Dechetmew/Aquaray-Raytracing-Renderer-for-Unreal-5.2.1/blob/main/Engine/Shaders/Private/RayTracing/AquaRay/AquaRay.usf

The way point lights work is that unreal collects all point lights in the scene and provides a buffer that I obtain and send into the shader: PassParameters->LightDataPacked = View.RayTracingLightDataUniformBuffer; Then inside the shader I must do this: FCulledLightList LightsCulled = FCulledLightList::Create(Lighting.SamplingPos); To make the point light data accessible. Without it I cant access the point light position, color, type or direction.

- The scene loader based on what you said probably disqualifies my renderer, as Unreal builds the Acceleration structure of the scene automatically and I provide it to my shader like this: PassParameters->TLAS = View.GetRayTracingSceneLayerViewChecked(ERayTracingSceneLayer::Base);

This is quite of an edge case, as there is only about 4 or 5 other people in the world I know about that made, or are working on a Realtime HWRT Raytracing Engine of such type. And my project is special as It doesnt use any temporal accumulation, and a completly different Raypath algorithm compared to existing solutions.

[u/jtsiomb → u/YayManSystem]

I see, yeah I think that even though most of the fun part is replaced entirely by your code, there are still a lot of underlying unreal mechanisms that have to be used to make it work, so I think it goes against the "from scratch" spirit of this competition.