Day 15 - Background Scrolling

What BG Effects?

	OK, now to BG scrolling. You might wonder why I didn't put this in Day 14. The
reason is that I though Day 14 would be easier to understand if I didn't give so much
at one time. The real reason is that I half forgot to/half was to lazy to put
this in Day 14. So here it is.


For Text Backgrounds, which we have not discussed, you just put the amount you want to scroll by in REG_BGxHOFS (horizontal) and REG_BGxVOFS (vertical) (x is the background number). For Rotation Backgrounds, REG_BGnX and REG_BGnY (n is BG number) are the registers that we want to mess around with. Since they are each 32bits (unlike the 2 mentioned in the previous paragraph, which are 16bits), we can set each one nice and separately. Just put the values in the registers, and ka poof! The BG Scrolls! Sample code: ldr r0,=REG_BG2X ldr r1,=1000 ; I'm not sure how much this would scroll by. str r1,[r0] ldr r3,=REG_BG2Y ldr r1,=1000 str r1,[r3] Simple right?

Day In Review

Hope you have fun scrolling your BGs! May Your Programs Run Without Bugs, -Mike H a.k.a GbaGuy
Intro - Day 16

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