Mode 7 to BG4

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iNCEPTIONAL

Mode 7 to BG4

Post by iNCEPTIONAL »

If I create a Mode 7 background image that looks like the one below, start with it zoomed in a large amount and then zoom out to 100% scale--I guess you don't really need to know this first part, but anyhoo--how many frames, roughly, would it take to then switch out the Mode 7 background at the end of the zoom for a single Mode 0 background that looks exactly the same?
Mode7_to_BG4.png
Mode7_to_BG4.png (5.68 KiB) Viewed 899 times
Note: The blue sky/water colour/gradient is not part of the BG layer but just the background/backdrop colour with a gradient applied using HDMA. I just thought the example image would look weird here with the pink-ish colour 0 that I use for all the palettes in the BG layer (or whatever number it's called).
Last edited by iNCEPTIONAL on Thu Aug 04, 2022 10:01 am, edited 3 times in total.
Myself086
Posts: 158
Joined: Sat Nov 10, 2018 2:49 pm

Re: Mode 7 to BG4

Post by Myself086 »

Mode 7 takes 32KB for its BG so If you can fit your mode 0 VRAM data into the other 32KB, it can be instantaneous. Otherwise you may need 1 black frame to copy the mode 0 data to VRAM.

Since you're only asking to have 1 BG in mode 0, it should fit just fine.
iNCEPTIONAL

Re: Mode 7 to BG4

Post by iNCEPTIONAL »

Myself086 wrote: Thu Aug 04, 2022 4:49 am Mode 7 takes 32KB for its BG so If you can fit your mode 0 VRAM data into the other 32KB, it can be instantaneous. Otherwise you may need 1 black frame to copy the mode 0 data to VRAM.

Since you're only asking to have 1 BG in mode 0, it should fit just fine.
OK, I think that sounds like I should have plenty VRAM left to be able to make it instant then.

The Mode 0 background is around 256 unique tiles (probably less) and one screen in size, and that's at 16 bytes per tile if they're 2bpp, so just 4096 bytes or 4KB (assuming blank tiles don't take up any meaningful space), right?

That's me trying to sound like I have a clue, so it could be all wrong.
Myself086
Posts: 158
Joined: Sat Nov 10, 2018 2:49 pm

Re: Mode 7 to BG4

Post by Myself086 »

iNCEPTIONAL wrote: Thu Aug 04, 2022 5:45 am
Myself086 wrote: Thu Aug 04, 2022 4:49 am Mode 7 takes 32KB for its BG so If you can fit your mode 0 VRAM data into the other 32KB, it can be instantaneous. Otherwise you may need 1 black frame to copy the mode 0 data to VRAM.

Since you're only asking to have 1 BG in mode 0, it should fit just fine.
OK, I think that sounds like I should have plenty VRAM left to be able to make it instant then.

The Mode 0 background is around 256 unique tiles (probably less) and one screen in size, and that's at 16 bytes per tile if they're 2bpp, so just 4096 bytes or 4KB (assuming blank tiles don't take up any meaningful space), right?

That's me trying to sound like I have a clue, so it could be all wrong.
16 bytes per 2bpp CHR.

2KB per screen. You said you're using 2 screens on the BG. That leaves 30720 bytes which translate into 1920 2bpp CHRs.
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