Path: utzoo!mnetor!uunet!husc6!cmcl2!nrl-cmf!ames!pasteur!ucbvax!USU.BITNET!FATXC
From: FATXC@USU.BITNET
Newsgroups: comp.sys.amiga
Subject: Scrolling SuperBitMaps
Message-ID: <8801230030.AA28130@jade.berkeley.edu>
Date: 22 Jan 88 23:26:00 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Lines: 24


  I am trying to use either a ScrollLayer() or BltBitMap() function to
scroll a superbitmap in a window.  The functions appear to work quite
well, but there is always an annoying flicker when several calls are
made to these functions in rapid succession.  Is there a way to prevent
the colors on the screen from flashing?  Could it be that the blitter
being done while the screen is being updated causes the flashing?  I
rember something like this causing trouble with updating the screen on
an IBM (*gasp*) machine when I was writing to video memory,  I had to write
routines (in assembly, no less) to wait for horizontal or vertical retrace
to occur before I could write to video memory without causing flicker.  IS
the same thing happening here? or is is something else entirely.  I have
seen some very nice scrolling rastports without flicker, so I assume it can
be done...

      Thanks in advance for any information.

                          J. Norman Gee
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