New experiment with PTDQ: dual playfield with both layers scrolling freely.
https://www.youtube.com/watch?v=mENnJygi5Eo
As usual, available from https://retream.itch.io/ptdq.
Fun fact: the foreground layer is triple-buffered, but that's a complete waste as no graphics rendering is performed; the reason is that the initial 5% was made months ago, but I got around to make the rest only now that my right arm is immobilized due to injury: it was just too much of a chore to write more code and to create more assets using just the left hand - and I'm not even left-handed (even just typing this is driving me nuts)!
LAYERS
Common:
* PTDQ system
* RGBWa color model
* 320x256 visible dots
* interleaved bitplanes
* horizontal and vertical scrolling
Background:
* 336x336 dots
* maximum 256 colors
Foreground:
* 672x576 dots
* maximum 81 non-transparent colors
* triple buffer
NOTES
* Both the layers reside in CHIP RAM.
* The layers use 6 bitplanes in all.
* If the foreground had not used 100% transparent dots, its maximum number of colors would have been 256.
* The foreground mode is changed by writing a whole 24-bit palette to the COLORxx registers with the CPU during the vertical blanking. The required palettes are pre-calculated at startup.
* The CPU is idle most of the time. The Copper is idle most of time (but if the staggered lines are on, it performs a wait and a write for each visible rasterline). The Blitter is idle.
* The triple buffer was implemented for glitchless rendering of graphics, but eventually no rendering was added.
* YouTube's encoding degraded the quality. Last edited by saimo on 09-Feb-2026 at 10:38 AM.
Last edited by saimo on 05-Feb-2026 at 05:32 PM.
Last edited by saimo on 05-Feb-2026 at 05:29 PM.
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