Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!cwjcc!gatech!psuvax1!psuvm.bitnet!dn5 From: DN5@PSUVM.BITNET Newsgroups: comp.sys.mac.programmer Subject: Re: help needed dragging a non-rectangular PICT Message-ID: <64148DN5@PSUVM> Date: 7 Dec 88 14:28:15 GMT References: <6095@mva.cs.liv.ac.uk> Organization: Penn State University - Center for Academic Computing Lines: 16 Hi, To drag something across another pattern I use two off-screen bitmaps. One is the background (I copy the background into this once, and then use it as a constant), and the other is the work bitmap. I copy the background into the work bitmap, then put the irregular region where it should be on this bitmap, then I CopyBits the work bitmap to the screen. This technique worked fast enough for me to rotate a simple polygon on a MacPlus in real-time (as a student dragged it around) or as animation (smooth, in 3 degree increments, which was the best comprimise of smoothness and speed). You will have to experiment to see how you want this to look, but I suggest testing it on the slowest machine you have (something that looks fast enought on a Mac II can look like a dog on a Plus). Jay, etc...