Algorithm for detecting when a freeform path self-intersects

[cracka]

Any of you programming geniuses have any ideas? I've tried per-pixel alpha value collision detection but sometimes aliased diagonal lines will trigger a "collision".

[Wyzard]

It'd make more sense to test for intersection using the internal mathematical representation of the path, which has no aliasing problems, rather than its rasterized representation onscreen.

Take a look through [url=http://www.google.com/search?q=cubic%20spline%20self-intersection&ie=UTF-8&oe=UTF-8]these search results[/url], for example. ([url=http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TYR-4PV94CX-1&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&_docanchor=&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=516b920ede7be4f831417ca408d44cb2]This article[/url] looks promising, but apparently costs $35.)

[cracka]

Done. Used the current time in milliseconds and a grid about 1/2-1/4s of the screen's resolution. Groovy.