From owner-freebsd-hackers Sun Jan 26 03:40:59 1997 Return-Path: Received: (from root@localhost) by freefall.freebsd.org (8.8.5/8.8.5) id DAA02934 for hackers-outgoing; Sun, 26 Jan 1997 03:40:59 -0800 (PST) Received: from haldjas.folklore.ee (Haldjas.folklore.ee [193.40.6.121]) by freefall.freebsd.org (8.8.5/8.8.5) with ESMTP id DAA02929; Sun, 26 Jan 1997 03:40:42 -0800 (PST) Received: from localhost (narvi@localhost) by haldjas.folklore.ee (8.8.4/8.8.4) with SMTP id NAA12413; Sun, 26 Jan 1997 13:38:28 +0200 (EET) Date: Sun, 26 Jan 1997 13:38:28 +0200 (EET) From: Narvi To: Terry Lambert cc: Jake Hamby , hasty@rah.star-gate.com, multimedia@freebsd.org, hackers@freebsd.org Subject: Re: New Bt848 Video capture driver for FreeBSD In-Reply-To: <199701252133.OAA00739@phaeton.artisoft.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk On Sat, 25 Jan 1997, Terry Lambert wrote: > > For the record, somebody wrote a bt848 driver for BeOS, and there's a demo > > of the new 3DKit which allows you to drop live video and/or QuickTime > > movies onto the faces of a 3D object (cube, sphere, pulsing thing, book > > pages), and spin it around in realtime. It looks _real_ sweet playing > > about 6 QT movies simultaneously on a PowerMac 8500, all texture-mapped > > onto various 3D objects, but a live video feed is even cooler. Man, I'd > > love to have the source code to that! > > I bet you $1 that they are only transferring data for the one, two, or > three visible faces of the cube. What do you think of them being fools? Everybody knows most things just drop a lot of frames when displaying video on the screen. Dropping a (at the current point of time) invisible video stream is not cheating, I even wouldn't consider using a hack that did not do so. But they still need to move the reference to the current frame in the six other movies. > > You could easily render a projection matrix to do this: > > o Start with a cube showing one face (ie: the vector from > your viewpoint through the center of the cube is perpendicular > to the plane of the face). > [snip - I don't care about checking the validity at the moment] Sander > > o For more complex rotations, you will rotate the cube center > as if it were attached to an axis with a fixed center by > moving the cube center relative. This is topologically > equivalent to rotating the cube about any point. You will > need to make another matrix for perspective, since if you > rotate about a point other than the body center, the average > distance to the body center will get farther (the cube will > "get smaller") or closer (the cube will "get larger"). > > > Regards, > Terry Lambert > terry@lambert.org > --- > Any opinions in this posting are my own and not those of my present > or previous employers. >