Everyone's A Wally: Routine at F3AB

F3AB: Room logic : The Sewer


F3AB	LD A,$40	Touching the shark drops endurance by 64, which can kill a player pretty quickly.
F3AD	LD ($F26E),A
F3B0	LD IX,$F3A3	Point IX to the movement table. (F3A3)
Make sure the shark is facing the right way.
F3B4	LD A,(IX+$02)	Get the distance to move in X.
F3B7	CP $02	Compare it to +2 ie: moving right.
F3B9	LD A,($F046)	Get the shark's direction.
F3BC	JR Z,$F3C4	If the distance is positive, nothing to do.
Shark should be facing left.
F3BE	OR A	Is the direction 0? (left)
F3BF	CALL NZ,$F047	If not, need to flip the shark the other way round.
F3C2	JR $F3C8	If not, need to flip the shark the other way round.
Shark should be facing right.
F3C4	OR A	Is the direction 0? (left)
F3C5	CALL Z,$F047	If so, need to flip the shark the other way round.
Now draw the shark.
F3C8	LD A,$30	Set the object ID to be the shark's head.
F3CA	LD BC,$F3A1	Point BC to the bounds table. (F3A1)
F3CD	CALL $EF35	Update the position.
F3D0	CALL $A8A0	Draw the graphic.
F3D3	LD A,($F3A0)	Get the next ID for the shark's body.
F3D6	XOR $02	Cycle bit 2 so it changes between 2D and 2F.
F3D8	LD ($F3A0),A	Cycle bit 2 so it changes between 2D and 2F.
F3DB	CALL $EF35	Update the position.
F3DE	CALL $A8A0	Draw the graphic.
Check to see if the player has the meat.
F3E1	LD A,($BD78)	Get the item in the sewer.
F3E4	CP $17	Is it the meat?
F3E6	RET Z	If so, the shark won't harm the player, so return.
F3E7	LD A,$17	Otherwise, is the player's first item the meat?
F3E9	CP (IY+$50)	Otherwise, is the player's first item the meat?
F3EC	RET Z	Return if it is.
F3ED	CP (IY+$55)	Otherwise, is the player's second item the meat?
F3F0	RET Z	Return if it is.
The player doesn't have the meat, if they touch the shark it's bad news.
F3F1	LD A,($A839)	Move up two rows and check collision detection.
F3F4	SUB $10
F3F6	LD ($A839),A
F3F9	CALL $E329
F3FC	RET	Return.