Pool-floor caustics derived rather than drawn: the reciprocal of the Jacobian determinant of the refracted wavefront, so the web appears exactly where the surface is focusing. Bass is the swell, highs the chop, and the same surface does the refraction and the reflection.
Drawn with: a WebGL2 shader.
Reacts to and looks like: gpu, webgl2 and water.
Family: Visualiser.
Runs in your browser. The preview above is the same program the renderer uses.