Future ideas

Broken Mirror effect: Vertical: https://i.ytimg.com/vi/4OFXhNuB0cU/maxresdefault.jpg

The core idea is to use Voronoi lines, as described here: http://www.iquilezles.org/www/articles/voronoilines/voronoilines.htm

The problem occurring in most implementations is actually what we're after, as we want irregular line width and cell omissions. The cell coloring can be done with an index in a noise texture, and then use a refraction function which uses the normal calculated for the cell from the value read from the noise texture to calculate what's visible in the cell, read from the original background.

Idea implementations:
https://www.shadertoy.com/view/ltSfRW
https://www.shadertoy.com/view/Mld3Rn