#Interlace problem
4 messages in this thread
Hello… This is a simple question, but through my lack of patience I've
decided enough is enough <smile>.
I'm having problems reading the Vertical beam position while in interlace
mode, and blittering a 4 bitplane image. It seems to me that I could wait
till the beam was at the bottom of the screen (during the even scans), then
blit in the image, but it still flickers <sigh>. What is the trick in
blittering in interlace. Isn't the LOF-frame flip-flop in VPOSR suppose to
indicate if the lines being scanned are Odd or Even? Please help….
Thanks… David
Blitter only moves 1 bit plane at a time. You might consider double
buffering.
Steve…
So is it impossible to determine the beam position in an interlace mode? I
would double buffer the screen, but I really didn't want to eat up all that
memory.
David
David, I don't know if it's impossible to determine the beam position —
however, even if you do, blitter will only move 1 bitplane at a time —
you're still going to get flicker. Double buffering is about the only way
to go.