[quote="Cheez":rpt6xbib]For one, the custom mask is already very frustrating to use, not the least of the reasons being that I can't edit it afterwards[/quote:rpt6xbib]
Agree. David said in his original implementation that he would expand on it in the near future to properly be able to select and move around points; it is very limited at the moment, but decidedly better than not having a custom collision mask at all. It's definitely unfinished though.
[quote:rpt6xbib]if an object happens to have a quarter circle in it or something along those lines, what do I do about that?[/quote:rpt6xbib]
Approximate it with a series of straight lines. Seriously, as far as I know, all commercial games also do this. A true curve is a rare thing to come by in computing simulation - as Arima said, they're faked. The physics interactions of a surface approximated by straight lines should be comparable to if it were a true surface. The more lines you use the more accurate it will be, but the more CPU it will use.
Also, Box2D physics (the engine behind the Physics behavior) doesn't support curves anyway. So we're stuck there!