Good question! This is actually a numerical solver for a few coupled partial differential equations - the method in this context (electromagnetism) is called FDTD. It's implemented as a WebGPU compute shader.
You absolutely could do this using WebGL2 compute shaders too, but I thought it would be fun to try this newer API.
You absolutely could do this using WebGL2 compute shaders too, but I thought it would be fun to try this newer API.