Avalon: Routine at 51854

51854: Trigger door opening or closing

Used by the routine at 51420.
Door opening/closing has been triggered. Jump from 51439 if bit 5 (32) of item properties byte (60238) is set, after Maroc has bumped into a door handle. Check made using collision check routine at 57293. Can be triggered by: Maroc bumping into a door to open or close it Servant closing a door Creature closing a door Missile fired by a creature closing an open door (e.g. rebounding off Maroc's shield)
51854	LD HL,(60241)	Door graphic address pointer in table at 38851
51857	LD E,(HL)
51858	INC HL
51859	LD D,(HL)	Address pointer to actual door graphics, e.g. 40248
51860	EX DE,HL	Swap into HL register pair
51861	INC HL	Swap into HL register pair
51862	LD B,(HL)	Get X co-ordinate pixel offset for graphic tile
51863	LD A,(60115)	Get graphic's X co-ordinate pixel position on screen
51866	ADD A,B	Add the pixel offset for the graphic tile
51867	LD D,A	Store in D register
51868	LD A,(60114)	Get vertical (Y) pixel co-ordinate
51871	SUB 16	The vertical co-ordinate starts at the bottom of the door, move up a bit to get to the door handle area
51873	LD E,A	Store in E register
51874	LD C,1	Collision/event type to check (1 = Door being opened/closed)
51876	CALL 57293	Run a collision check (item/Maroc vs door handle)
51879	CP 0	Was there a collision?
51881	JR NZ,51958	If not, jump out of this routine
A door handle has been touched so initialize door opening/closing
51883	LD A,(60238)	Door properties byte
51886	AND 15	Keep bits 0-3
51888	OR 64	Set bit 6 (indicates door is now opening or closing)
51890	JR 51955	Set bit 6 (indicates door is now opening or closing)