Date: Sun, 26 Jan 1997 13:38:28 +0200 (EET) From: Narvi <narvi@haldjas.folklore.ee> To: Terry Lambert <terry@lambert.org> Cc: Jake Hamby <jehamby@lightside.com>, hasty@rah.star-gate.com, multimedia@freebsd.org, hackers@freebsd.org Subject: Re: New Bt848 Video capture driver for FreeBSD Message-ID: <Pine.BSF.3.95.970126132853.12382A-100000@haldjas.folklore.ee> In-Reply-To: <199701252133.OAA00739@phaeton.artisoft.com>
next in thread | previous in thread | raw e-mail | index | archive | help
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. >
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?Pine.BSF.3.95.970126132853.12382A-100000>