shape cutout

[markie]

I don't know whether this still is context-free, but i'll have it a try..

To make patterns more transparent, it might be useful to be able to cutout forms, so that f.i. a black square minus another, slightly smaller black square would leave a line-square with nothing inside. When i't done within a rule i think it's context-free..

The way I do this now is mostly putting a white square into a larger black one, but the result is of course not transparent.
The other, better way is to build transparent shapes from "lines", which is slower and less versatile.

Brightness-substraction would be a logical next step: black minus white would leave mid-grey.

[MtnViewJohn]

I am thinking of having an arbitrary polygon feature where you would specify a bunch of vertices and whether to stroke and/or fill them. This set of vertices could be multiple closed polygons such that some polygons would punch holes out of other polygons.