Right, midway through the rewrite. It is now a ray-marched 3D procedural cloud renderer.
ShareX capturing is causing the jerkiness - I’m getting around 30fps on average at about 720p.
I haven’t done anything about depth sorting, the most opaque sample owns that pixel and is responsible for lighting it. I’m going to have to add an input for the sun direction, since shaders have no access to that by default, which is quite annoying Epic. 
After that I can light the clouds when the sun is behind them.
The controls are things like storminess, fluffiness, reflectiveness, etc.
Performance is about the same but the quality is through the roof. This might become a next-gen effect if I can’t fix that up.
