Been a while since I looked at this bit of code, but Elite does the whole division thing. Not surprising really - the authors were super-proud of their maths routines, so they used them! Deepish dive: elite.bbcelite.com/deep_dives/l... The clipping code: elite.bbcelite.com/cassette/mai...

Might take a closer look at their code to see if there are any tricks i can borrow.

Yeah I just had a quick scan of the code. Don’t blame them tbh.

I'm slightly puzzled. They are doing a load of division, but surely it's more efficient to do the chop that you describe?

Maybe. But it is probably quicker than drawing the entire line and writing a 16 bit plot routine that checks each point is on screen.