I see Codea can import vector PDFs. What sort of tools are available to create them? I’ve looked around and can’t find anything other than really expensive software.
I personally like InkScape which is an SVG editor, but it also exports to PDF. If you’re not looking for free ones, but cheap ones, LMK.
LaTeX? (No, that’s not spam.)
I thought LaTeX was (in its own words) a high quality typesetting program, rather than a drawing program. But I don’t doubt you could draw with it anyway!
Just a small sample.
If you want to produce vector images on an iPad then I would recommend iDraw, being able to copy the pdf to the clipboard means it is easy to import into codea.
Inkscape is very good for free.
Look at tutorials on SVG once produced you just have to convert them to pdf.
iDraw is great for simple art even beginners and you can copy and paste it into codea when you’re in the sprite viewer