Awesome

Tracer

Tracer is a renderer using C++, Embree and USD to produce photorealistic images using Path Tracing techniques on the CPU.

Screenshots

• USD Kitchen, using the UDPT, Diffuse, Position, Normal and Debug integrators:

<img src="https://i.ibb.co/CPKcY58/tracer-render-udpt.png" width="320" height="180"> <img src="https://i.ibb.co/0yZdGqq/tracer-render-diffuse.png" width="320" height="180"> <img src="https://i.ibb.co/fqnQrBs/tracer-render-position.png" width="320" height="180"> <img src="https://i.ibb.co/Trg5H3W/tracer-render-normal.png" width="320" height="180"> <img src="https://i.ibb.co/xHCYrnY/tracer-render-debug.png" width="320" height="180">

Features

• Rendering:

  • Progressive rendering
  • Render/export to PPM
  • Render/export to EXR

• Camera:

  • Types:
    • FPS
    • TODO : DCC-style
  • Subpixel jitter antialiasing
  • Depth of Field (using aperture radius and focal distance)

• Integrator:

  • UDPT (Unidirectional Path Tracing):
    • TODO : Environment Sampling
      • TODO : Color-based sky/background
      • TODO : Image-Based Lighting (IBL)
    • TODO : Light Sampling/Next Event Estimation (NEE)
    • BSDF Sampling
  • Diffuse (WIP)
  • TODO : Occlusion
  • Position
  • Normal
  • Debug
    • Render the equivalent of Pixar USD's primID on the geometry

• Sampling:

  • RNG:
    • Uniform
    • Stratified (WIP)
  • Methods:
    • Hemisphere:
      • Uniform
      • Cosine Weighted
    • Sphere:
      • Uniform

• Material:

  • TODO : Default
  • TODO : Diffuse
  • TODO : Empirical (for experiment purposes)
  • TODO : Disney (2012)

• BSDF/Lobes:

  • Diffuse:
    • Lambert
    • TODO : Oren-Nayar
    • TODO : Burley
    • TODO : Sheen
    • TODO : Subsurface Scattering
  • Specular:
    • TODO : GGX
    • TODO : Beckmann
    • TODO : Clearcoat
    • TODO : Thin Film

• Light sources:

  • Sky/background light
  • TODO : Geometry light

• Geometry types:

  • Meshes
    • Triangle-based
    • Quad-based
    • TODO : Subdivided
  • TODO : Curves
  • TODO : Primitives (sphere, cube...)
  • Instances:
    • Per-geometry instancing ("Everything is an instance" philosophy)
    • TODO : Native, multiple instancing of geometry prototypes

• Acceleration structure:

  • Intel Embree native BVH
  • TODO : Custom-based

• Scene:

  • Format:
    • Pixar USD
      • As .usd/usda/usdc/usdz
  • Ingested types:
    • TODO : Materials
    • TODO : Cameras
    • Geometry:
      • Meshes
      • TODO : Curves
      • TODO : Primitives
      • TODO : Instances
    • TODO : Light sources

• Utility:

  • GUI using ImGui
  • Pause/resume render
  • Front/backbuffer swapping
  • FPS counter

How to use

Tracer was written using Linux, VSCode as the IDE, CMake as the building tool, and a GCC C++17 compiler in mind.

Download the source, build the project structure using CMake 3.x, open the project using your favorite IDE (tested on VSCode), build the project, and everything should be ready to use.

Dependencies

The following set of dependencies, when applicable, is more or less based on the VFX Reference Platform 2023. It should be noted that the versions exposed here are the ones I personally used to develop and build the project in its current state. Depending on the projects, different versions, older as newer, would certainly work.

• Included:
  • Arguments Parsing: CLI11 (2.3.2)
  • Logging: spdlog (1.12.0)
  • Math Operations: Intel Common Library (3.5.2)
    • TODO : Needs to update the codebase to make use of the appropriate 3.13.5 version.
  • EXR Handling: tinyexr (0.9.5)
  • OpenGL Functions Loader: GLAD (0.1.36)
  • GUI System: ImGui (1.89.9)
• Not Included:
  • Multithreading: Intel TBB (2020.3)
  • Ray Tracing Kernels: Intel Embree (3.13.5)
  • Boost (1.80.0)
  • Scene Description: Pixar USD (23.08)
    • Core library only, Hydra/Imaging/Python support unnecessary.

Credits

• TODO