🚀 go-pugleaf

Greetings,

This weekend, while noodling around with animation, I came across a
most puzzling phenomena.  My graphics displayed fine while on the
lower part of the screen (I am using a monochrome 1040), but when
my little critters got about 30 or 40 pixels from the top they
started to get a bad case of the flickers.  I was using Vsync() to
control flicker, and it seemed to work well, except for this
twilight zone. 
 
I pulled my hair out for a couple of hours on this one, dug thru all
my books, and finally, at about 1 a.m., in the premier issue of START,
found a comment in an article about al graphics that went like this:

"...vsync, but you will still see flicker near the top of the screen.  This
is a problem that can only be dealt with by very complex multiple screen
flipping techniques..."

So, does anyone know of this problem?  What causes it? And, Virginia, how
can I eliminate it?


Bob Currier
currier@romeo.cs.duke.edu
rdc@northlab.ac.duke.edu