Algorithms for clipping lines to a rectangle seem to have been invented by Ivan Sutherland in the late 60s.
At some point the rectangle was generalized to an arbitrary polygonal area, and these days can be any path (including bezier curves, etc.)
It seems that Weiler and Atherton may have been the first to generalize polygon clipping in this way (http://www.cs.drexel.edu/~david/Classes/CS430/HWs/p214-weiler.pdf) but anyway the idea was taken up in 2D graphics APIs such as PostScript.
My question is: who had the idea of providing "clipping path" functionality in a 2D drawing API? Was it a PostScript invention, or is there some earlier 70s system that had the feature?
This comparison of PostScript with Interpress implies that Interpress didn't have clipping paths: "Beside that PostScript maintains a current clipping path that outlines the area of the current page that may be imaged upon. Initially this is the total imageable area of the page. This area can be modified by a clip operator." https://www.daube.ch/docu/pdl03.html