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Beginners > Mode 4 Scroll Background 1 pixel at a time

#32821 - QuantumDoja - Tue Dec 28, 2004 2:01 pm

Hi, With Mode 4 we draw two pixels at a time, but if i want smooth scrolling like that of super mario etc, they move the screen in 1px increments, how is this possible, if we have to draw two pixels per time????

any help is appreciated.
_________________
Chris Davis

#32837 - tepples - Tue Dec 28, 2004 4:18 pm

NES ports and all the Super Mario Advance games use mode 0, not mode 4.
_________________
-- Where is he?
-- Who?
-- You know, the human.
-- I think he moved to Tilwick.

#32838 - Datch - Tue Dec 28, 2004 4:18 pm

Drawing two pixels at once doesn't mean you have to scroll by two pixels increment.

Read/write access to VRAM are 16 bits. If you want to draw a single pixel, get the pixel you want and his neighhor (total of 16 bits). Modify the pixel you want and keep the other pixel value. Finally re-write the total 16 bits value to VRAM.

I've never done any scrolling in mode 4 but I guess that, depending of what you want to do, you should considered tiles mode.