A list of path tracing shaders

I have gathered a list of path tracing shaders on ShaderToy.

Path tracing is a surprisingly simple technique to render realistic images. This would be my definition if you are unfamiliar with the term. But if you already have experience with various ray tracing techniques, I would probably say that path tracing is a remarkably elegant solution to the rendering equation. You can implement a toy path tracer in a weekend or, if you’ve already done it a few times before, within 25 minutes.

Recently I was documenting myself on path tracing, and some of the techniques that can be used, like next event estimation, bidirectional path tracing, Russian roulette, etc. This is a case where ShaderToy can be an invaluable source of examples and information, and so I was browsing path tracing shaders there. As the number of open tabs was starting to get impractical, I decided to use the “playlist” feature of ShaderToy to bookmark them all.

You can find the list here: Path tracing, on ShaderToy.

The examples of path tracers listed include very naive implementations, hacky ones, rendering features like advanced BRDF, volumetric lighting or spectral rendering, or various noise reduction techniques such as next event estimation, bidirectional path tracing, multiple importance sampling, accumulation over frames with temporal reprojection, screen space blue noise, or convolutional neural network based denoising.

Some of those shaders are meant to be artworks, but even the technical experimentation ones look nice, because the global illumination inherent to path tracing tends to generate images that are pretty.

Screenshot of the list on ShaderToy, with various kinds of path tracers visible.

Reverse engineering the rendering of a frame in Deus Ex: Human Revolution

Earlier this year, Adrian Courrèges wrote an article detailing his findings while reverse engineering the rendering pipeline in Deus Ex: Human Revolution.

Starting from a given frame, he illustrates the different stages in the rendering: creation of the G buffer, shadow map, ambient occlusion, light prepass, how opaque and transparent objects are treated differently, volumetric lights, bloom effect in LDR, anti-aliasing and color correction, the depth of field, and finally the object interaction visual feedback.

Here are a few screenshots stolen from his article:

Normal map

The light pre-pass

Final image

Adrian since then posted a new article, this time breaking down the rendering of a frame in Supreme Commander. The comments also include insights from the programmer then in charge of the rendering, Jon Mavor.

Volumetric light scattering

Here are a couple of links on how to render light scattering effect (aka. volumetric shadows):


Lighting and atmospheric effects in Reset

I’m a bit late to the party, noticing that , co-founder of Praxis, wrote a series of articles presenting an overview of the tech involved in the rendering engine he’s writing.

Shading and atmospheric effects in Praxis’ engine

The results are visually impressive, so it’s very unfortunate he doesn’t give more details. This video in particular, showcasing real-time atmospheric effects is outstanding.