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Date: Sun 09-Mar-1989 04:49:59 From: Unknown Subject: A few questions about the display I am giving consideration to buying a NeXT machine and I have a few questions concerning the machine's support of display PostScript which I haven't been able to find answers to. 1) Is the display setup as a (logical) device so you can send it a stream of PostScript source just like any other PostScript device? 2) Is any of the graphics support in hardware? 3) Do you setup a PostScript "display list" that is interpreted in (pseudo)parallel with other CPU tasks (analogous to the copper display list on the Amiga or the old Atari 8-bit graphics display list). 4) How close to the "standard" is the display PostScript used in the machine? And, is so-called "Display" PostScript really any different from a standard "Printing" PostScript implementation? 5) If there is no/little hardware support is there any chance that there will eventually be a graphics coprocessor/graphics engine available for the NeXT machine? 6) (This follows from the answers to the other questions, but I'll ask it explicitly anyway). Will the display support "artifacted"/dithered (I can't think of the right term off-hand) display of gray levels above and beyond the 4 gray scales supported. Also, can the brightnesses for the four colors (gray scales) be changed? 7) Are the gray scales implemented with bit-planes so that eventual color (well, at least more gray scales) support will be "consistent" with original graphics model? and finally, (8) if the support is all in software and this is a true implementation of PostScript, how the h*ll can it be as fast as it is? Thanks, Drew ( If someone thinks answers to these questions are relevant to the pop. of this board post an answer, otherwise send me personal e-mail. Also, could someone tell me exactly WHO has NeXT machines at this point in time? ) Andrew Kompanek ARPA: ak10+@andrew.cmu.edu Carnegie Mellon University Research Assistant, The Robotics Institute >From: greggt@VAX1.CC.UAKRON.EDU (Gregg F. Thompson)
Date: Sun 10-Mar-1989 03:48:32 From: Unknown Subject: Re: A few questions about the display In article <UY5U9ry00W0GEIP0wK@andrew.cmu.edu> ak10+@andrew.cmu.edu (Andrew Joseph Kompanek) writes: >I am giving consideration to buying a NeXT machine and I have a few questions >concerning the machine's support of display PostScript which I haven't >been able to find answers to. > >1) Is the display setup as a (logical) device so you can send it a stream > of PostScript source just like any other PostScript device? Sort of. The connection to the postscript server is through mach ports rather than via something like /dev/postscript, but it is perfectly simple to tell it to eat a bunch of ASCII postscript. There's a demo program called yap that does just that. >2) Is any of the graphics support in hardware? Not as far as I can tell. >3) Do you setup a PostScript "display list" that is interpreted > in (pseudo)parallel with other CPU tasks (analogous to the copper display > list on the Amiga or the old Atari 8-bit graphics display list). The postscript server is a Unix process that runs in parallel with yours. You blat postscript at it, and it does it. Although you can send regular ASCII postscript, what programs do in practice is to send a new compact encoding, defined in Display postscript, which you get from a compile-time preprocessor. >4) How close to the "standard" is the display PostScript used in the machine? > And, is so-called "Display" PostScript really any different from a standard > "Printing" PostScript implementation? DPS is a superset of regular printer postscript. It adds a bunch of stuff that is quite handy for working on screens, e.g. graphic state objects that encapsulate the context of a window. >5) If there is no/little hardware support is there any chance that there > will eventually be a graphics coprocessor/graphics engine available > for the NeXT machine? Widely spread rumors claim that Pixar is building one. >6) (This follows from the answers to the other questions, but I'll ask > it explicitly anyway). Will the display support "artifacted"/dithered > (I can't think of the right term off-hand) display of gray levels > above and beyond the 4 gray scales supported. Also, can the brightnesses > for the four colors (gray scales) be changed? You can set your gray level to any floating point value from 0.0 to 1.0 and DPS will dither as best it can. Looks pretty decent. You can't change the four hardware colors other than turning the brightness up and down. >7) Are the gray scales implemented with bit-planes so that eventual color > (well, at least more gray scales) support will be "consistent" with > original graphics model? Yes. DPS already has support for arbitrary colors, though at this point setting your color to .32334 red, .98745 green, and .27458 blue doesn't do you much good. >and finally, (8) if the support is all in software and this is a true >implementation of PostScript, how the h*ll can it be as fast as it is? I guess it's magic. More to the point, for all of the fast animation you see, they precompute bitmaps and composite them around, which turns out to be quite effective.
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