Path: chuka.playstation.co.uk!scea!greg_labrec@interactive.sony.com From: jamin1@psu.edu (Jamin Frederick) Newsgroups: scea.yaroze.programming.2d_graphics Subject: Re: pixels Date: Wed, 09 Jul 1997 18:31:17 GMT Organization: SCEA Net Yaroze News Lines: 38 Message-ID: <33c3d7f6.4808700@news.scea.sony.com> References: <33c122d9.168381829@news.scea.sony.com> NNTP-Posting-Host: nb5ppp166.cac.psu.edu X-Newsreader: Forte Free Agent 1.11/32.235 On Mon, 07 Jul 1997 20:22:09 +0100, ira@netcomuk.co.uk (Ira Rainey) wrote: >In article <33c122d9.168381829@news.scea.sony.com>, jamin1@psu.edu (Jamin >Frederick) wrote: > >> Hi, how's it going? I'm working on my pixel-by-pixel collision >> detection algorithm, and I've run into a problem of actually trying to >> access pixel data of sprites. It seems like I won't be able to access >> the data the lies in the video memory once it has been transferred >> from the main memory, since there are no api calls to do this > >It's just a thought, but how about setting yourself an area of memory >aside, the size of the bounding box of your sprite, as a buffer. Then when >you want to test to see if a collision has occured, first test the >bounding box area, if that is true then copy that bounding box into your >main memory area buffer using StoreImage(); then test it there. If the >pixels collide you can run your collision stuff, if not drop back to the >main loop. > In fact, I would only need to copy the *intersection* of the two sprites' bounding boxes, both the same size, a section from each sprites' image, into main memory with StoreImage(). The question is, whether StoreImage() is fast enough to be doing transfers pretty frequently, probably almost every frame or so. I'll try this method and see if I have any problems. Otherwise I'll use the main memory comparison thing. Jamin >What does anyone else think? > >Ira > >-- >"The difference between the impossible and the possible lies in determination" -- Tommy Lasorda