Path: utzoo!attcan!uunet!comp.vuw.ac.nz!virtue!ccc_ldo
From: ccc_ldo@waikato.ac.nz (Lawrence D'Oliveiro, Waikato University)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Fading ...
Message-ID: <895.268a6c9d@waikato.ac.nz>
Date: 28 Jun 90 08:46:21 GMT
References: <838.26826323@waikato.ac.nz> <554@ohs.UUCP>
Organization: University of Waikato, Hamilton, New Zealand
Lines: 25

In <554@ohs.UUCP>, stay@ohs.UUCP (Steve Taylor) suggests:

"What about using n stages of patterns, and drawing the original
picture (off of just one off-screen bitmap) n times masked through the
pattern?  (Paint the source picture with the pattern and the correct
transfer mode and use copy-bits with the right mode to transfer each
stage over.)"

The whole point of my original posting was to do the dissolve
as *quickly* as possible using standard QuickDraw calls, and
secondarily to avoid using too much memory. If you draw the source
picture n times, you need n source pixmaps (in the case of colour).
For maximum speed, these pixmaps should be the same depth (and
have the same CLUT) as the current screen setting. With my original
approach, you only need one such pixmap; all the rest are one-bit-
per-pixel bitmaps. So I think my approach consumes significantly
less memory, as well as being faster (only one DrawPicture call).

Still, might be worth actually trying it...

Lawrence D'Oliveiro                       fone: +64-71-562-889
Computer Services Dept                     fax: +64-71-384-066
University of Waikato            electric mail: ldo@waikato.ac.nz
Hamilton, New Zealand    37^ 47' 29" S, 175^ 19' 16" E, GMT+12:00
Schrodinger's Cat may have died for your sins.