Sorry for the late reply. I didn’t check itch very often.
I’ve tried updating my existing project from Godot 3.5.2 to 4 before, however it took me too much time to fix various bugs. Finally I gave up due to some lingering runtime bugs which I cannot solve. I think I will stay with 3.x for a bit longer.
Back to your question. If you’d like to upgrade this script to Godot 4, you need to change two parts. (1) Change FOV_DATA into an object, as I noticed that in Godot 4, constants can no longer be modified. (2) Change func_host and block_ray_func into a Callable function.