I'm currently running into these sorts of line-drawing bugs myself (in the C API) and even though I really, really don't want to, I'm considering taking the plunge and writing my own line rasterizer just to overcome them...
Ew, no good. Thanks for waking this thread up, I must have missed it the first time around. I've got a fix for Jaggies with drawLine but it only fixes the glitches in the green circles. I'll add these to the issue, hopefully get a fix out soon.
Oh, that's great! Does that fix cover the linked bug report in OP, too?
Also, using pd->graphics->drawLine() with width=0 vs. width=1 specifically documented anywhere? What's the difference supposed to be? Aside from some of these endpoint issues, width=0 looks more like a standard one-pixel line to me...
Nope, looks like that linked issue is still there. But I've got all three linked in the issue, so I'll sort them all out. I probably won't include Line with 2px width rasterizes to 1px width in this because I think it's an entirely different problem.
Awesome! If I don't have to write a line rasterizer from scratch to get perfectly-drawn pixel lines from the C API that will be just fantastic—I'd much rather work on just about anything but that. Thank you!