Hi all.
I made something a few weeks ago that I thought might be useful, so I somewhat tutorialised it here:
http://www.pixelninja.design/manhattan-voronoi-approximation/
Basically it's a method of achieving something close to a Manhattan-distance voronoi diagram.
I hope someone out there finds this useful
If anyone knows of a better method, or a method of achieving an actual Manhattan voronoi I'd love to hear it!
ManhattanApproximation_01.hiplc