<div class="bbCodeBlock bbCodeQuote" data-author="jollyroger">
<div class="attribution type">jollyroger said:
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As far as I remember from my experiments from ages ago, this is precisely what Burning Rangers does, including a lower resolution draw for the transparent layer and the reuse of the same framebuffer for both the transparent layer and the background layer in a single frame, before swapping. The only difference may be the exact timing of the copies between the framebuffer and the VDP2 ram, and whether BR goes through work ram or elsewhere, which I don't actually recall right now.[/quote]
</div> Since you can't do scu dma from vdp1 to vdp2, I guess it goes to work ram.
BR uses a 176x112 part of the screen and scales it to 2x for both x and y.
But it also covers the upper left part of the screen, so as I understand it it sends a end command, wait until it finishes drawing and retrieve it, clear the FB and starts drawing the main sprites after transfering to a vdp2 layer.
I could be wrong, but I guess it has an extra 16 ms delay because of that, while the technique I do is - imo - easier and maybe faster.
I draw the transparent sprites offscreen first, so when I retrieve the FB the drawing of that part of the screen will be completed for sure, so I don't need to wait.
I will still have to clip/mask the transparent sprites to allow something similar to BR.