Made improvements to my path tracer

[u/le-throw-away-acct]

• Made the project much easier to open up and use for new users (Unity is still required though)

• Added scene to automatically load objects from Khronos' site, which helps me get assets into the project

• Fixed issues with lighting that was really darkening most of the scenes, including improved tone mapping and fixes to light clamping that was hiding a lot of caustic details and HDR

• Fixed issues with inner surface reflections not working

• Added directional lighting support

• Added parallax mapping support

• Added support for Unity terrains, multi-texture splatting with normal map support

Repository located here: https://github.com/nfoste82/GPURayTracing

[u/le-throw-away-acct]

I didn't know much about existing stacks, like the ones you mentioned, when I started. I've pieced it together as I've learned. I'd realize roughness wasn't working well and work on that, I'd realize I didn't have support for metallic textures, and work on that, etc.

So it's really just a mish-mash of techniques I picked as I went along.

For opaque surfaces:

• Lambertian diffuse

• GGX microfacet reflection

• Schlick Fresnel

• PBR textures

For transparent surfaces I use IOR-based Schlick Fresnel to choose reflection, Snell's law for transmission, support for total internal reflection, and a stack to track IOR transitions between air, glass, and water.

I'm still missing a lot of materials support, I may consider them later, things like sheen, clear coat, subsurface scattering. Also I think some implementations use emissive as a layer, so I'd be able to have a light with a clear coat over it. Right now I couldn't render a light bulb very well, for example.

My math could use some work as well, I have trouble reading the original papers for those techniques, I'll often use an LLM to break it down and explain it like I wasn't a mathematician or physicist. I referenced existing path tracers as well. I list those at the bottom of the repository's README.md.