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From: krowitz@RICHTER.MIT.EDU (David Krowitz)
Newsgroups: comp.sys.apollo
Subject: Re:  ...animation
Message-ID: <8812201611.AA09712@richter.mit.edu>
Date: 20 Dec 88 16:11:44 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
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If you can manage it, what you want to do is to draw your next
frame in a bitmap in the hidden display memory rather than in
main memory and BLT it onto the display. Unfortunately, the
hidden display memory on the DN3xxx/4xxx is much smaller than
on previous machines, so you can't really draw a whole screen,
only small objects which you are going to place onto the screen.

The graphics hardware on the DN3xxx/4xxx is not all that fast
(the "C" and "E" color options) compared to the DN550/560 and
the DN660. I understand that the new "F" option color display
is much faster. Try to avoid BLT'ing whole screens -- the more
data you have to move, the worse the flickering -- it's 
frequently faster to erase only the section of the screen
where something has changed and to redraw that small section.
Take a look at the code for BZONE and STWAR in the ADUS library.
They may give you a few ideas, although they both do line
drawings, not filled-area graphics.


 -- David Krowitz

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