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Rastah Bar
Registered: Oct 2012
Posts: 336 |
Double buffering color ram in half of the screen?
Suppose you have some text or MC bitmap graphics only in the bottom half of the screen, perhaps you could double buffer (color ram & gfx) using FLD?
I mean: in one frame you first switch to an empty screen in the top half (where you have some sprite action, say) and in the bottom half you switch to the desired graphics screen. In another frame you FLD the top half of desired color ram & gfx down to the bottom half.
Don't know if this can be useful though. |
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Rastah Bar
Registered: Oct 2012
Posts: 336 |
I wasn't really thinking about a game. I just posted it to get the discussion going. Perhaps it might be useful for some kind of interlaced graphics effect in an intro or demo. But I guess speedcode is the preferred technique in any case.
Cruzer, thanks for the link. Really cool (or should I say "chilly"?) demo. It is the effect just before the twister, isn't it? I love that twister, btw, so colorful. |
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Peiselulli
Registered: Oct 2006
Posts: 81 |
Yes, it is the greetings part.
The double buffer color ram has a nice feature: If you scroll not at maximum speed and you need for example only a frame update every 4th frame, than you can build up a quarter of the screen with color ram in one of each of this frames. So you need to update only 120 chars (=240 bytes) per frame if you scroll with 2 pixel per frame.
The idea comes from Groepaz (he posted it some years ago in the Forum64) btw. |
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chatGPZ
Registered: Dec 2001
Posts: 11100 |
actually the idea is even older... some other guy came up with a japanese-style bullet-hell shooter like thingy which used this technique and posted it here on csdb even more years before. too bad i totally forgot the name of the guy or the production (maybe someone else remembers?) |
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Krill
Registered: Apr 2002
Posts: 2825 |
And there are more benefits, beyond technical advantages: there are 256 freely-positionable double-height tiles (8x16 or 4x16 pixels), which is (almost) double as much graphics to play with for a graphician/level designer. :) |
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ChristopherJam
Registered: Aug 2004
Posts: 1370 |
Quote: actually the idea is even older... some other guy came up with a japanese-style bullet-hell shooter like thingy which used this technique and posted it here on csdb even more years before. too bad i totally forgot the name of the guy or the production (maybe someone else remembers?)
That was Doynax's Balls of the Scrolling Thunder; he commented extensively about it in the Sorting discussion ten years ago. |
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chatGPZ
Registered: Dec 2001
Posts: 11100 |
mmmh but where is it then? pretty sure it had a csdb entry too.... *shrug* |
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ChristopherJam
Registered: Aug 2004
Posts: 1370 |
Never completed to my knowledge. |
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chatGPZ
Registered: Dec 2001
Posts: 11100 |
no, but binary posted and added as "preview". i certainly have run it myself :)
edit: Balls of Scrolling Thunder Preview |
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Rastah Bar
Registered: Oct 2012
Posts: 336 |
Quote: That was Doynax's Balls of the Scrolling Thunder; he commented extensively about it in the Sorting discussion ten years ago.
Quoting doynaxThe d800 copy is double buffered and evenly distributed across 16 frames, so it really doesn't take much raster time at all ;)
Yes, I remember having seen this, but how does he do it? With linecrunching or FLD? |
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chatGPZ
Registered: Dec 2001
Posts: 11100 |
in one frame, push down the screen 12(?*) (raster)lines using FLD, then create 12 doubled (character)lines. in the second frame crunch the first 12(?*) lines and then create 12 doubled lines.
(*) not sure if that is the optimum if you also want to do vertical scrolling |
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