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DS development > Large bitmap rendered over the two screens

#120597 - Leviathan2040 - Sun Mar 04, 2007 11:19 pm

Ok, it is my turn to play the nOOb...

I read hundreds of messages regarding how to set up both Top and Bottom screens as MOD 5 with 256 x 256 x 16 bits tile.

However one of the many things that I still don't get, is why the memory assigned to the screen are always A & C rather than A & B? The reason I ask that, is that I need to display a rather large bitmap scrolling across the screen, what I want to achieve is that when the bitmap scroll upward and the top part of it is moving off the bottom screen it starts to appear on the top screen as well. If the two memory banks were consecutive I would not need fire up the rendering algorithm twice, but just one as it happens now, because the two memory banks are not consecutives.

Can anybody can help me? Thanks in advance.

BR,
Lev

#120622 - simonjhall - Mon Mar 05, 2007 1:19 am

I don't think the second graphics engine (ie the one assigned to the subscreen) is able to access banks A/B so you've got to point it at C and beyond instead.

Check this:
http://nocash.emubase.de/gbatek.htm#dsvideodisplaysystemblockdiagram
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#120701 - Sausage Boy - Mon Mar 05, 2007 5:49 pm

It's simply a matter of which banks can be used for what. I find dovoto's Large intimidating table very useful for finding this out.
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#120809 - HyperHacker - Tue Mar 06, 2007 5:42 am

You could use B for main and C for sub.
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#120812 - tepples - Tue Mar 06, 2007 6:20 am

You need to fire it up twice anyway, as there's a roughly 96 pixel gap between the screens.
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