danielthompson / polytope

Hobby ray / path tracer in C++

Polytope

Hobby ray/path tracer in C++.

Goals

• Path tracer
• Support a variety of materials and reflection / transmission models
• Acceleration structures
  • bounding volume hierarchy
  • kd-tree
• Import a variety of scene / object description grammars
  • .pbrt
  • .obj
  • .ply
• Render paths
  • vanilla CPU
  • Explicit SPMD with ispc
  • CUDA
  • Rasterization with OpenGL (or Vulkan)

Renders

Lambertian reflection:

Specular reflection:

Instancing:

Bounding-volume hierarchy heatmap:

Triangle intersection heatmap:

What's a polytope?

In elementary geometry, a polytope is a geometric object with "flat" sides. It is a generalisation in any number of dimensions of the three-dimensional polyhedron. Polytopes may exist in any general number of dimensions n as an n-dimensional polytope or n-polytope.

https://en.wikipedia.org/wiki/Polytope

Does polytope render polytopes?

Polytope represents all shapes internally as triangle meshes, which are 3-polytopes. Input grammars that specify other types of geometry (implicit surfaces, etc) are tesselated on import to triangle meshes.

Attribution

The structure and terminology of this project is inspired by pbrt (https://github.com/mmp/pbrt-v3). My MO is generally to:

1. Originally develop and implement a feature to the point that it works; and then
2. See how the pros did it; and then
3. Adjust my own implementation if necessary / desired.

This project uses code from the following libraries / projects:

• pbrt
  • https://github.com/mmp/pbrt-v3
  • Matrices and transforms
• Google Test
  • https://github.com/google/googletest
  • Unit testing
• LodePNG
  • https://github.com/lvandeve/lodepng
  • For exporting raw image data to PNG