Re: A85: Sprite Routines

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Re: A85: Sprite Routines


>
>If anyone wants the library to attempt to port the routines to the 85, I'd
>be glad to send the most recent version to them.  There is a new Collision
>routine which has so far been untested.  So, I have no idea if the 82 will
>even crash or not using that routine.  Collision will detect a SOLID
>collision between two shrunken bounding boxes of any two (they can even be
>different sized) sprites.  However, remember it's untested and so it might
>have a bug or two in it.
>

speaking of collision routines, here is the one i used in solomon's
key.  its real fast, and works with sprites (bounding boxes) of the
same size.

;Square Sprite collision routine.
;Input:
;  a has the size of the length of the square edge (a = 8 for 8 pixel
sprite)
;  bc has (x,y) of top left of first sprite
;  de has (x,y) of top left of second sprite
;Output:
;  carry flag set if no collision occurs
;  carry flag reset on collision
;Destroys:
;  a
SpriteCollision:
   dec a
   add a,b
   cp d
   ret c                        ;no collision
   sub b                        ;reg a again has edge length
   add a,d
   cp b
   ret c                        ;no collision
   sub d
   add a,c
   cp e
   ret c                        ;no collision
   sub c
   add a,e
   cp c
   ret c                        ;no collision
   or a                         ;clear the carry, collision!
   ret

-mike pearce
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