Path Tracer

An NEE + MIS path tracer, supports various BxDFs / Lights / Volumes and Monte Carlo effects.

Rough glass (alpha = 0.05) bunny with HDRI lighting

Rough glass bunny with Microfacet Conductor background

Disney Principled Bunny with Microfacet Conductor background

Left: Rough gold material, Right: Marschner Hair material

Cornell box with homogeneous fog, rendered with volumetric integrator.

Build Instructions:

This project uses CMake to build and is correctly built under M1 macOS environment. The C++ standard is set to C++ 20.

Once CMake is installed, use below commands to build with CMake.

This project uses OpenMP for parallization, for ARM Mac users, please refer to this [post][https://stackoverflow.com/questions/71061894/how-to-install-openmp-on-mac-m1] .

Add GL_SIMD to compile definition to enable SIMD (for vec and matrix class).

mkdir build
cd build
cmake ..
make .

• Unit tests are under /tests folder using GTest framework.

Integrator:

• The path tracer uses an importance sampling strategy, a mixed PDF of Material PDF and light sampling with NEE (next-event-estimation).

• Other integrator includes

  • Volumetric path tracer (only null-tracking for now. NEE WIP)
  • An analytical calculation for Polygonal diffuse only lighting. (Ref. James Arvo)
  • Russian Roulette version MIS, w./w.o. NEE

Monte Carlo and Post-processing effects:

The path tracer supports DoF, motion blur. Image filtering and tone-mapping.

Materials:

1. Marschner Hair
2. Phong
3. Dielectric (Microfacet BxDF + simple dispersion approximation)
   • Thin Dielectric
   • This branch introduces a split-ray variant for noise reduction.
4. Conductor (Microfacet BRDF, VNDF)
5. Lambertian
6. Kajiya-Kay
7. Disney Principled BSDF (A mix of 2015 / 2012 impl.)

Object IO

1. .obj
2. .fbx (WIP)

Light

• Area light
• Sphere light
• HDRI (IBL)

Sampler

1. Halton Sampler
2. Stratified Sampler
3. Sobol Sampler (WIP)