Hi,

before I embark on the mission of writing this incredible spaghetti code myself , has anyone perhaps implemented or stumbled upon some 6502 code that performs line clipping (supporting negative coordinates, if possible)?

Thank you,

Rudla

Perhaps have a look at this disassembly of Acorn's MOS:
https://tobylobster.github.io/mos/mos/S-s8.html#SP22

And perhaps look at Elite's code in this disassembly and write-up:
https://www.bbcelite.com/deep_dives/bre ... rithm.html
https://www.bbcelite.com/deep_dives/line-clipping.html

Look for the "Cohen Sutherland" algorithm. It's quite generic and while very possible to optimise for certain hardwares it will get you off to a good start especially if you already have a good line drawer like Bressenham.

https://en.wikipedia.org/wiki/Cohen%E2%80%93Sutherland_algorithm

-Gordon

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Gordon Henderson.
See my Ruby 6502 and 65816 SBC projects here: https://projects.drogon.net/ruby/