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.
Patater GBAGuy Mirror
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
Just put the values in the registers, and ka poof! The BG Scrolls!
ldr r1,=1000 ; I'm not sure how much this would scroll by.
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