Posted By
Csabo
on 2023-07-07
08:55:31
|  Re: Flickering PETSCII software sprites
You're on the right track, and the two methods you described are the major approaches.
If you only use "one screen", you should always draw the areas that are not being displayed to avoid flicker. This is done with FF1D or raster interrupts. This will give you "full frame-rate", 50 FPS on PAL (and I'll just mention that in our demoscene, this is sometimes referred to as "realtime", even though that's a misnomer).
Otherwise you can use double-buffering. The idea is still the same - you draw to a place that's not being displayed. Since it's super easy to switch the location of the video ram with $FF14, this is easy to implement. No matter how many frames it will take for you to draw a full screen, you can just switch to it when you're done, then start drawing to the other one. It's not full frame-rate, but absolutely flicker-free (and it costs more memory).
Hope this helps 
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