Siren is an "asynchronous tile-based GPU pathtracer". It runs compute dispatches on square tiles, which each run an iterative process computing how rays bounce around in the scene. It grew out of a project called SDF_Path, which in turn grew out of my early raymarching experiments. It uses some some pretty basic brute-force pathtracing approaches, with signed distance fields as scene geometry. It also supports ray-primitive intersectors, but with no BVH in place... their utility is very limited. Eventually, I got to the point where I wanted to do a rewrite, and started on Daedalus. You can find out more in the articles below: