Path Tracer

My personal implementation of a roughly "feature complete" Path Tracer. The beginnings of the codebase were roughly identical to the Path Tracer constructed during the Handmade Ray Day 1 livestream, archived at https://guide.handmadehero.org/ray/ray00/. From then, I programmed the rest "in the dark" (for the most part); i.e., I didn't consult any open source Path Tracer implementations. To guide development, I sourced content from books, which I reference in the References section below. I'm aware that this isn't the ideal approach for writing a Path Tracer as fast as possible; I chose this approach because I was looking for a coding adventure :)

Features

• Importance sampling Monte Carlo Integration.
  • GGX importance sampling.
  • Emissive sphere importance sampling.
  • Cosine sampling.
• Materials:
  • Specular BSDF from microfacet theory: GGX distribution function, Smith joint shadow-masking courtesy of Hammon et al., and Slick approximation of Fresnel equations.
  • Uniform diffuse BSDF.
  • Albedo, roughness, metalness, and normal textures.
  • Disney "principled" roughness parameterization.
• Physical lens model.
• GLTF import.
• Supported Geometry: Triangles, Spheres, Planes, AABBs, Quads.
• Multithreaded architecture.
• Live viewer.
• Output .BMP image format.

References

• I read https://www.pbr-book.org/4ed/Monte_Carlo_Integration and maybe other chapters.
• I own a physical copy of https://www.realtimerendering.com/; I sampled various chapters, especially chapter 9.
• I read the entire series to ensure completeness of my implementation:
  • Ray Tracing in One Weekend
  • Ray Tracing: The Next Week
  • Ray Tracing: The Rest of Your Life
• Importance sampling GGX: https://schuttejoe.github.io/post/ggximportancesamplingpart1/

Usage

e.g.: "AutomataApp.exe -t16 -p16 -nmr"

t<int>                        - Set the number of threads to use.
p<int>                        - Set the rays to shoot per pixel.
w<int>                        - Set the world number to load. Possible options:
  1:  Default scene.
  2:  Metal-roughness test.
  3:  Cornell box.
  4:  Ray Tracing in One Weekend book cover.
  5:  Mario N64 model.
    
d                             - Enable depth of field via thin-lens approximation.
n                             - Disable loading normal map textures.
m                             - Disable loading metalness material textures.
r                             - Disable loading roughness material textures.
h                             - Print this help menu.

Steps for Building

This project depends on my game engine, Automata-Engine. You can find that here: https://github.com/BluBloos/Automata-Engine

The engine has its own dependencies, but the TLDR is:

• this project only works on Windows
• install Python and make sure its on your PATH
• install MS Visual Studio 2022, community ed. and ensure it is located at "C:\Program Files"

To build and run the raytracer on the scene, please run the following.

build.bat
bin\AutomataApp.exe

Happy path tracing!