go-pt

This project is a Monte Carlo path tracer written in Golang that runs on CPU.

Features

Implemented

• Parallel processing on multiple CPU cores
• BVH trees for accelerating intersection tests
• Positionable camera with adjustable focal length and aperture
• Transformations (translation, rotation)
• Materials:
  • universal material with adjustable properties:
    • albedo:
      • texture or color
    • roughness (GGX microfacet model)
    • index of refraction
    • amount of clearcoat
    • roughness of clearcoat
    • metalicity
    • transmission
  • Emission material:
    • emission color
• Support for OBJ files:
  • loading vertices, texture coordinates and normals
  • triangle fan triangulation of polygons
  • support for materials from MTL files
  • support for image textures
  • normal smoothing
• Textures
  • Generated textures:
    • checkerboard (based on UVs or coordinates)
    • grid with variable line thickness (based on UVs or coordinates)
  • Image textures
• Environment textures
  • Can be loaded from normal image files or from Radiance HDR files (loaded using hdr library)
• Nishita sky model with a sun

To-do

• Building scenes from files (probably JSON?)
• More primitives and BVH trees for them
  • Constructive solid geometry
• Volumetric rendering
• Importance sampling
• Spectral rendering

Usage

For now, scene has to be set in main.go file, I'm planning to add support for reading scenes from files in the future. This program has only one external dependency, it's hdr library, to install it, run the following command:

go get github.com/mdouchement/hdr

If you're not planning to use HDRI environment maps, remove the following line from the top of main.go file:

_ "github.com/mdouchement/hdr/codec/rgbe"

To run the program, type the following command:

go run .

Example renders

Some of the models downloaded from Morgan McGuire's Computer Graphics Archive. The Go gopher was designed by Renee French. (http://reneefrench.blogspot.com/). The gopher 3D model was made by Takuya Ueda (https://twitter.com/tenntenn). HDRI image used in one of the examples was downloaded from HDRI Haven. Textures used in one of the examples were downloaded from TextureCan and Texture Haven.

Mori knobs - rough copper, rough glass, glossy plastic

A scene with Nishita sky model with sun (denoised in Blender)

Render of a scene with materials with different level on roughness from my path tracer on the left and reference render from Blender on the right

Four spheres with different textures and materials with HDRI environment map

Cornell box with mirror box