I'm trying to cut a polygon layer with a line I've created in part by copy-pasting lines from various source shapefiles and in part by hand-drawing segments to connect those.
For clarity, the end goal is to carve out a new polygon from a set of preexisting polygons, where the line I've drawn is part of the border and the shared outline of the original polygons is the other part of the border. I imagine once I cut the original polygons properly, I can simply join the cut bits I want fairly straightforwardly.
Some more info:
- The line I've drawn is in a MultiLine layer and isn't technically one line, though it could in theory be joined into a single continuous line if I knew how to do that; as it is there's a number of points of overlap and tails off the 'main' line that I'd be happy to do away with
- This hypothetical continuous line doesn't encircle a polygon (except in one point where the 'main' line I want is one part of the boundary of a polygon I converted to a line); I'd like to use it to cut the set of polygons it's drawn across
- I've tried the Digitiser Tools Plugin, which other answers claim has a 'cut polygon layer with lines from a line layer' tool; I don't seem to see this option
What sequence of manipulations do I need to do to cut my polygons with this line?