I am trying to write a fragment shader in GLSL for a fog effect in a 2D game.
Here are some links showing what I'm after.
Here the fog is in the foreground and near the ground: https://twitter.com/i/status/992811158318075904
Here the fog is on a background layer and fills the screen: https://twitter.com/i/status/963889084337983488
Here the fog is more subtle and denser near the ground: https://twitter.com/i/status/1001926421856563205
I am interested in learning how to create these effects. Unfortunately, I am pretty new to shaders and only know how to do elementary stuff like color swaps, outlines, and simple vignettes. It doesn't help that it's hard to find resources on shaders with a bent toward 2D.
In the environment in which I'm working, I can attach a shader script to any of my sprites, parallax background layers, etc.
Does anyone have advice on creating these kinds of effects?