Haskell Path Tracer

A simple path tracing implementation written in Haskell using accelerate.

This has recently been rewritten to make better use of streams so it can be parallelized better and so we can support features that require splitting rays such as refraction. At the moment the new implementation is still significantly slower than the old one.

Building

This application requires LLVM 9.0.1 to build, and the GPU version requires CUDA 10.x until the bindings are updated. Support for LLVM 10 is tracked in this issue. To compile and run, simply run:

cabal run -j tracer

Running without a GPU

The application uses Accelerate's PTX LLVM backend by default. To run the application without an NVIDIA GPU simply pass the cpu flag to the application:

cabal run -j -fcpu tracer

Native dependencies

Because of the reliance on LLVM, OpenGL and SDL there are a few non-Haskell dependencies. These can be installed as follows:

Debian, Ubuntu and derivatives

Debian and Ubuntu ship older versions of LLVM than those supported by this project so it might be necessary to install LLVM's from their own repositories.

sudo apt update
sudo apt install libsdl2-dev libsdl2-ttf-dev llvm-9-dev

Arch, Manjaro and derivatives

sudo pacman -S sdl2 sdl2_ttf llvm9

Resources

Haskell is hard. Computer graphics is hard. So here are some very useful resources for implementing all of this.

The accelerate-examples repository includes a ray tracer. This is very useful for getting a feel for expressing regular imperative graphics routines in terms of Accelerate programs.
Scratchpixel is an amazing resource on all things computer graphics. They include detailed explanations of how things should work and why they are implemented the way they are.