This project demonstrates how to create complex voxel objects in Unity ECS using Compound Colliders. Each voxel consists of a rendering material instance data and box collider.
The path tracer is by INedelcu.
[Pathtracing] https://github.com/INedelcu/PathTracingDemo
[MeshInstancing] https://github.com/INedelcu/RayTracingMeshInstancingSimple
See my post on Unity Forums regarding Compound Colliders:
https://forum.unity.com/threads/coding-compound-colliders.1506245/#post-9439400
Youtube Demo of this Engine:
https://www.youtube.com/watch?v=O1Si7Evk-mo
My Other YouTube Demos of INedelcu's Path Tracer: