micro@imada.dk (Klaus Pedersen) (11/07/90)
In a review of the TT in "ST Magazin", there was a short note about a new Shifter mode called "Sample&Hold". What is it and how does it work??? (the article said something about HAM and lotsa colors!). What happend to the 256 GRAYSCALE mode of the TT ? (is it still there, or what??) What is the display reflech rate of the TT (TT-LOW/TT-HIGH) ? Klaus (micro@imada.dk)
cmm1@cunixa.cc.columbia.edu (Christopher M Mauritz) (11/08/90)
In article <1990Nov7.154503.9366@imada.dk> micro@imada.dk (Klaus Pedersen) writes: >In a review of the TT in "ST Magazin", there was a short note about a new >Shifter mode called "Sample&Hold". ^^^^^^^^^^^ Must be the new Neil Young mode. :-) BTW, did they ever start selling these things in the US? Chris ------------------------------+--------------------------- Chris Mauritz |D{r det finns en |l, finns cmm1@cunixa.cc.columbia.edu |det en plan! (c)All rights reserved. | Send flames to /dev/null | ------------------------------+---------------------------
apratt@atari.UUCP (Allan Pratt) (11/08/90)
micro@imada.dk (Klaus Pedersen) writes: >Shifter mode called "Sample&Hold". >(the article said something about HAM and lotsa colors!). SAH mode has nothing to do with lots of colors. What it lets you do is draw filled polygons really fast. You can draw two dots on the screen and get a solid line between them, without having to write the color value to all the pixels in between in memory. Example below. > What happend to the 256 GRAYSCALE mode of the TT ? It's there. > What is the display reflech rate of the TT (TT-LOW/TT-HIGH) ? That's "refresh rate" and the color modes are 60Hz no matter what country you're in. TT HIGH rez is 1280x960 monochrome, and its frame rate is 67hz, I think. EXAMPLE OF SAH MODE: In SAH mode, nonzero pixel values in memory appear as that color, and zero pixel values in memory mean "continue with previous color." That's why it's also called "smear" mode: a colored dot will "smear" to the right until it reaches another nonzero pixel value. In the diagrams below, a period (".") is a zero dot and a star ("*") is a one. In addition, a zero ("0") represents a pixel value which has the same color as the background. Let's say you want a picture like this: ........ ..****.. ...**... ..****.. ........ You can get it by drawing this: ........ ..*...0. ...*.0.. ..*...0. ........ This means you only had to write six pixels, not thirteen. Of course, this is just a sample: the savings is much more dramatic for bigger pictures. (The trailing "0" in the second picture is what stops the smear from going all the way to the right edge of the screen. The left edge starts out in the background color.) ============================================ Opinions expressed above do not necessarily -- Allan Pratt, Atari Corp. reflect those of Atari Corp. or anyone else. ...ames!atari!apratt
cbdougla@uokmax.ecn.uoknor.edu (Collin Broad Douglas) (11/08/90)
In article <2735@atari.UUCP> apratt@atari.UUCP (Allan Pratt) writes: >micro@imada.dk (Klaus Pedersen) writes: >>Shifter mode called "Sample&Hold". >>(the article said something about HAM and lotsa colors!). > >SAH mode has nothing to do with lots of colors. What it lets you >do is draw filled polygons really fast. You can draw two dots >on the screen and get a solid line between them, without having >to write the color value to all the pixels in between in memory. >Example below. > >EXAMPLE OF SAH MODE: > >In SAH mode, nonzero pixel values in memory appear as that color, and >zero pixel values in memory mean "continue with previous color." That's >why it's also called "smear" mode: a colored dot will "smear" to the >right until it reaches another nonzero pixel value. > >[munch munch] >..****.. >...**... >..****.. >........ > >You can get it by drawing this: > >........ >..*...0. >...*.0.. >..*...0. >........ > >This means you only had to write six pixels, not thirteen. Of course, >this is just a sample: the savings is much more dramatic for bigger pictures. > > >============================================ >Opinions expressed above do not necessarily -- Allan Pratt, Atari Corp. >reflect those of Atari Corp. or anyone else. ...ames!atari!apratt You all will like this new feature. We have in on the Apple IIGS (but we call it fill mode). It's really fun to have. I believe the GS version of Tunnels of Armagedon uses this mode. I've also got a couple of animation demos that use it. I just with Rainbird would do ports of Carrier Command and Mid Winter using fill mode :). then I'd be a happy camper! Collin Douglas cbdougla@uokmax.ecn.uoknor.edu P.S. anyone know of a decent CAD for the Atari ST? My roomate has an ST and I'd like to get a CAD. The only PD CADs for the GS are old and bad (old meaning they don't even use GS graphics :( CAD Apple is a little out of my price range :( :( ). Thanks for any help. even use h