bgget

can someone expain how to use bgget for backround colision i keep on getting a out of range error?

BGGet(X,Y,F) return the cell on the coordinate X,Y. X,Y could be pixel unit if F == 1 or tile unit if F == 0. The first 12 bits represent the tile, the rest are used for transformation. You could do something like this:

// SP is the management number of the sprite
// VX and VY are the speed in pixel unit
// Return true if the sprite overlap a tile different to 0

DEF collisionWithBG(SP,VX,VY)
 VAR X,Y,W,H,C

 C=0
  
 SPCOL SP OUT X,Y,W,H
 INC X,VX
 INC X,VY
 INC W,VX
 INC H,VY

 INC C,BGGET(X,Y,1)
 INC C,BGGET(X+W,Y,1)
 INC C,BGGET(X,Y+H,1)
 INC C,BGGET(X+W,Y+H,1)

 RETURN C
END

The code above get the collider of the sprite and then check if it overlap a tile different to 0(Empty). If you want to know if the collider is overlapping certain tile then you could do something like this.

// SP is the management number of the sprite
// VX and VY are the speed in pixel unit
// T is the tile id without transformation.
// Return true if the sprite overlap a tile T.

DEF collisionWIthTileT(T,SP,VX,VY)
 VAR X,Y,W,H,C
 VAR FILTER=&B111111111111

 C=0
  
 SPCOL SP OUT X,Y,W,H
 INC X,VX
 INC X,VY
 INC W,VX
 INC H,VY

 INC C, (BGGET(X,Y,1) AND FILTER)==T 
 INC C, (BGGET(X+W,Y,1) AND FILTER)==T
 INC C, (BGGET(X,Y+H,1) AND FILTER)==T
 INC C, (BGGET(X+W,Y+H,1) AND FILTER)==T

 RETURN C
END

That's the pixel per frame that the sprite move. VX is the movement from left to the right. VY is the movement from top to the bottom.