Newsgroups: comp.sys.amiga.advocacy Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!think.com!mintaka!geech.gnu.ai.mit.edu!rjc From: rjc@geech.gnu.ai.mit.edu (Ray Cromwell) Subject: Re: NeXT/Amiga Flamage: Get a life. Message-ID: <1991Apr10.035203.3854@mintaka.lcs.mit.edu> Sender: news@mintaka.lcs.mit.edu Organization: The Internet References: <10902@uwm.edu> <&5aGlabl1@cs.psu.edu> <1991Apr10.005729.22997@cunixf.cc.columbia.edu> Date: Wed, 10 Apr 91 03:52:03 GMT Lines: 57 In article <1991Apr10.005729.22997@cunixf.cc.columbia.edu> es1@cunixb.cc.columbia.edu (Ethan Solomita) writes: >In article <&5aGlabl1@cs.psu.edu> melling@cs.psu.edu (Michael D Mellinger) writes: >> >>In article <10902@uwm.edu> gblock@csd4.csd.uwm.edu (Gregory R Block) writes: >> >> >> Yes, which is only usable on the CUBE, which is about 8000 dollars, or more... >> >>Of course. I was just correcting an incorrect statement made by an Amiga user. >> >> The 12 bit color with 4 alpha channel is the color slab, a likewise joke. >> >>Hey, 4096 colors looks pretty impressive :-). >>And on a million pixel display, to boot. >> >>-Mike > > I must be missing something here. The 040 is about three >times faster than the 030, right? And the color NeXT is 12 bits >as opposed to 2 bits on the old NeXTs, or six times the bit >planes. So, the color NeXT is twice as slow with the graphics/GUI >as the original NeXT, right? Assuming the NeXT uses the CPU to do it's rendering which it probably does unless the color NeXT's have a blitter. > Truthfully I don't know what an alpha channel is. Is it >basically an overlay screen? From what I understand, alpha channel is transparency. I'm not used to it in a 2d sense, but in a high end z-buffered graphics system, Alpha channel specifies how much color to borrow from the pixel underneath. So if you have a blue sphere behind a red sphere, an alpha channel value of 128 (with 8 bits of alpha) specifies a 50% blending (im guessing here. I don't know how the real implementation of alpha works). So in theory, 50% of the color of the blue pixels would "show thru" the red's causing the red sphere to be partially transparent. Pretty neat for speeding up 3d rendering without using dithering. I have no idea of how alpha works in a 2d system with no Z buffer. I guess it changes into 'anti-aliasing blending' from neighboring 4x4 pixels. Talk aabout expensive displays. I've heard about frame buffers out there that have 24 bits color, 8 bits alpha, 32 bits z buffering, 1 bit overlay, 2 bits of control, and even gamma correction. All this totals more than 64 bitplanes. I heard SUN even developed displays in excess of 100 bits per pixel! > -- Ethan > >Q: How many Comp Sci majors does it take to change a lightbulb >A: None. It's a hardware problem. -- /~\_______________________________________________________________________/~\ |n| rjc@albert.ai.mit.edu Amiga, the computer for the creative mind. |n| |~| .-. .-. |~| |_|________________________________| |_| |________________________________|_|