This is not a single shader, the animation is done with JS/canvas 2d, the shader does just the refraction.
I wrote an article about it here[1], but I made this back when I was first learning WebGL (it was my first WebGL project, in fact), so be aware that a lot of things could be better!
I wrote an article about it here[1], but I made this back when I was first learning WebGL (it was my first WebGL project, in fact), so be aware that a lot of things could be better!
[1]https://tympanus.net/codrops/2015/11/04/rain-water-effect-ex...