MiniRayTracerPBR

$$ L_o(p, \omega_o) = L_e(p, w_o) + \int_{\Omega}f(p, \omega_i\rightarrow\omega_o)L_i(p, \omega_i)\cos\theta\mathrm{d}\omega_i $$

Multithread RayTracer(Cook-Torrance BRDF model, metallic workflow) implemented by C++.

The basic code frame comes from GAMES101.2020 Assignment7.

Features

• Cook-Torrance BRDF model
• metallic workflow(material can be adjusted by [albedo, roughness, metallic], I've defined three materials(copper, silver, gold) in main.cpp as example)
• importance sampling microfacet-based BSDF for GGX NDF(normal distribution function)
• speed up intersection detection of triangle mesh with BVH
• implement anti-aliasing by create random ray inside one pixel.(not by filter)

Results

spp16	spp32

spp128	spp512

spp512 rough metal	spp512 marble floor

Bugs

• SOLVED Rarely there will be particularly bright noise pointer, I think it's caused by dividing very small float(some pdf could be), maybe just spp is not high enough or algorithm's limitation?

Future work

• random number generation is very expensive
• the implementation of Multi-threading needs to be improved(divide into blocks)
• the code is untidy and needs cleaning
• support common types of textures(normal map, albedo/roughness/metallic map..)
• support transparent/anisotropic materials

References

• https://learnopengl.com/PBR/Theory
• http://jcgt.org/published/0007/04/01/paper.pdf
• https://agraphicsguy.wordpress.com/2015/11/01/sampling-microfacet-brdf/
• https://schuttejoe.github.io/post/ggximportancesamplingpart1/
• https://computergraphics.stackexchange.com/questions/7656/importance-sampling-microfacet-ggx
• https://sites.cs.ucsb.edu/~lingqi/teaching/resources/GAMES101_Lecture_16.pdf
• https://sites.cs.ucsb.edu/~lingqi/teaching/resources/GAMES101_Lecture_17.pdf
• https://github.com/Bly7/OBJ-Loader

Tips

• please run the program in release mode, make sure you are not in debug mode when testing your high spp result(otherwise it will be a disaster).
• It takes about 270 seconds to complete the rendering(mingw-w64/gcc) when spp=512 with cpu i7-9750H(2.60GHz,6c12t)