Copo-tracer is a project mainly written in C and C++, it's free.
A raytracer with some tests for snow rendering
This is a small test environment to render scenes with a ray-tracer. It is meant to elaborate some different snow rendering techniques. There are no further dependencies. The original source code was provided by Sören König (Soeren.Koenig AT tu-dresden.de). You are free to modify and/or redistribute that code in terms of the BSD license.
The project uses cmake and recommends an out-of-source build, e.g. for a Linux system:
mkdir build
cd build
cmake ..
make