Automatic BG Scroll?

Hi. Well, I created a cutscene, and it have a special effect: the BG scrolls virtually, and not the FG and the objects layout, with this code, in the "resize" subroutine:



subq.w #5,($FFFFF700).w



Later, I added the REV01 bg scroll system, and moved the cutscene to GHZ1, but this code causes the game crash. I tried to move the BG directly from Deform_GHZ, but simply I can't understand the format.


How I can do this effect? I just need to use this effect for 4 1/2 seconds. I think, I need use a different code or RAM, but what?


EDIT: It just works, if I change the subq by addq, but it causes the bg scrolls in reverse XD

 

Seems like your questions soughted. But just thought i'd ask, have you tried putting a negative value into it?

 

Yes, and it makes the camera scroll in reverse, or crash

 

$FFFFF700 is the horizontal camera position for the foreground. If you want to move the background, you would have to use $FFFFF708.


Also, it crashes because you move the camera to a negative position, which is impossible to handle for the engine.