Since it looks I’m the only one interested in those drawing functions I didn’t bothered uploading the code, thought I’ll ask Dom to include it to sdlutils.

The thick line function is problematic, it simply uses many AA_Line => performance and quality drop.
I still need to add polygon render function.

you can download the updated test app from here
Keys:
[*/] Rotate
[+-] Scale
[Arrows] to move the ant
[Key pad] to 'move the world'
[1..4 + mouse click] to control the curve
[5 + mouse click] to move the line