Nice writeup! I'm a fan of shader sandwiches like yours. Judging from the stated limitations and conclusion, I bet this would benefit tremendously from a switch to WebGPU. That's not a criticism! If anything, you're effectively demonstrating that WebGL, a sometimes frustrating but mature ubiquitous computing platform, can be a valuable tool in the hands of the ambitious. Regardless, I hope to fork your repo and try a WebGPU port. Good stuff!