[comp.sys.mac] "DissBits"?

siegel@endor.harvard.edu (Rich Siegel) (04/04/89)

A long time ago,  I saw a demo of a routine called "DissBits", which
was a dissolving analog of CopyBits. Does anyone know who the author 
is and/or how to get source for this routine?

Thanks in advance...

R.

~~~~~~~~~~~~~~~
 Rich Siegel
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 Symantec Corporation, Language Products Group
 Internet: siegel@endor.harvard.edu
 UUCP: ..harvard!endor!siegel

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 and sat in the pudding." -Emo Phillips
~~~~~~~~~~~~~~~

alibaba@ucscb.UCSC.EDU (Alexander M. Rosenberg) (04/04/89)

The author's name is Mike Morton. He wrote articles
on the routine for MacTutor and for Dr. Dobbs.

I think his email address is:
msm@uhmanoa.ics.hawaii.edu


The routine is written in Assembly and only works
for 1-bit depth situations, although it should be
fairly simple to fix that problem.


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stuartb@microsoft.UUCP (Stuart Burden) (04/04/89)

In article <1536@husc6.harvard.edu> siegel@endor.harvard.edu
(Rich Siegel) writes:
  | A long time ago,  I saw a demo of a routine called "DissBits", which
  | was a dissolving analog of CopyBits. Does anyone know who the author 
  | is and/or how to get source for this routine?

I think Mike Morton is the author of DissBits (if I recall I've seen
him talk about it in this forum).  I have a copy of a version of DissBits
around here somewhere, but it is a few years old now.  If there is a more
recent version, let me be one of the first "me to's".  What I would really
like to see, is some C source to disolve PixMaps.  Perhaps some generous
soul will post the most recent version of DissBits, or some disolving
PixMap code.

  | Thanks in advance...
  | Rich Siegel
  | Symantec Corporation, Language Products Group

Stu.

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oster@dewey.soe.berkeley.edu (David Phillip Oster) (04/05/89)

In article <1223@microsoft.UUCP> stuartb@microsoft.UUCP (Stuart Burden) writes:
>I think Mike Morton is the author of DissBits (if I recall I've seen
>him talk about it in this forum).  I have a copy of a version of DissBits
>around here somewhere, but it is a few years old now.  If there is a more
>recent version, let me be one of the first "me to's".  What I would really
>like to see, is some C source to disolve PixMaps.  Perhaps some generous
>soul will post the most recent version of DissBits, or some disolving
>PixMap code.

Even more fun: if the pixmap is on a device that supports color lookup
tables, you can use SetEntries to repeatedly decrease the values in all
the color entries, and do a fade to black that is dead smooth. Chris
Derossi's INIT Dimmer probably uses this technique.  Then, while the
screen is black, you CopyBits in a new pixmap, and slowly restore the
color table to be equal to a second color table. In this way you can do a
smooth fade through black (or uniform gray) to another image.  Even
fancier things are possible.  Be sure to have a backup technique for the
program to use when it is running on a black&white only display, or on one
that doesn't support modifying the CLUTs (such as the 24-bit per pixel
displays that are beginning to appear.)

Note: some of these 24-bit per pixel displays have so much video memory
that Color Quickdraw has to throw the system into 32-bit addressing mode
to get at them. thePort->portBits.baseAddr will lie to you if you try to 
use it to get at screen memory directly, so watch it!

My "Stars" uses a similar technique to Mike Morton's, but I wrote my own
code for it (with algorithm suggestions from Matt Grayson). My version is
even faster than Mike's.

--- David Phillip Oster            --"When we replace the mouse with a pen,
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lsr@Apple.COM (Larry Rosenstein) (04/06/89)

In article <28686@ucbvax.BERKELEY.EDU> oster@dewey.soe.berkeley.edu (David 
Phillip Oster) writes:
> tables, you can use SetEntries to repeatedly decrease the values in all
> the color entries, and do a fade to black that is dead smooth. Chris
> Derossi's INIT Dimmer probably uses this technique.  Then, while the

The problem with this is saving the old values, worrying about protected 
entries, etc.  Dimmer probably just sets the gamma table, and this 
technique could be used for smooth fade ins/outs.

Larry Rosenstein, Apple Computer, Inc.
Object Specialist

Internet: lsr@Apple.com   UUCP: {nsc, sun}!apple!lsr
AppleLink: Rosenstein1