Robotron: 2084: Routine at 59127

Used by the routine at Process_Cluster_Entity.

Per-frame entity handler for the slow player-tracking enemy. Tests player contact via HitTestBounds8AtHL; triggers death via Strip_Attributes_And_Fade if touching. Computes the signed Y and X distance from the player at 50388 and 50389 halves it five times to derive a velocity nudge, and negates if the enemy is above or to the left of the player. Reads the entity facing byte; on a random 1-in-8192 chance sets it to 26 (freeze state). If the facing is 26 flips both velocity components and tests for a 1-in-256 chance to clear the freeze. Applies the computed Y and X nudge to the entity position, clamping to the play area, and draws the entity via Draw_Entity_Sprite.

Used by the routine at Process_Cluster_Entity. Per-frame entity handler for the slow player-tracking enemy. Tests player contact via HitTestBounds8AtHL; triggers death via Strip_Attributes_And_Fade if touching. Computes the signed Y and X distance from the player at 50388 and 50389 halves it five times to derive a velocity nudge, and negates if the enemy is above or to the left of the player. Reads the entity facing byte; on a random 1-in-8192 chance sets it to 26 (freeze state). If the facing is 26 flips both velocity components and tests for a 1-in-256 chance to clear the freeze. Applies the computed Y and X nudge to the entity position, clamping to the play area, and draws the entity via Draw_Entity_Sprite.
Process_Player_Tracking_Enemy	59127	LD HL,50388	Set the player Y address in alternate HL and test player contact via HitTestBounds8AtHL; trigger death via Strip_Attributes_And_Fade if touching.
	59130	EXX
	59131	CALL HitTestBounds8AtHL
	59134	JP NC,Strip_Attributes_And_Fade	Step back three bytes to the entity Y position and load the player Y coordinate at 50388.
	59137	DEC HL
	59138	DEC HL
	59139	DEC HL
	59140	LD C,(HL)
	59141	EX DE,HL
	59142	LD A,(50388)
	59145	LD L,A	Compute the signed Y nudge: subtract the entity Y from the player Y, halve five times, and negate if the entity is above the player.
	59146	LD H,0
	59148	LD B,0
	59150	AND A
	59151	SBC HL,BC
	59153	BIT 0,H
	59155	LD A,L
	59156	JP Z,Process_Player_Tracking_Enemy_Nudge_Y
	59159	NEG
Process_Player_Tracking_Enemy_Nudge_Y	59161	SRL A	Scale the Y nudge and restore its sign.
	59163	SRL A
	59165	SRL A
	59167	SRL A
	59169	SRL A
	59171	BIT 0,H
	59173	JP Z,Process_Player_Tracking_Enemy_Nudge_X
	59176	NEG
Process_Player_Tracking_Enemy_Nudge_X	59178	EX AF,AF'	Compute the signed X nudge from the player X coordinate at 50389 in the same way.
	59179	LD A,(50389)
	59182	LD L,A
	59183	LD H,0
	59185	INC DE
	59186	LD A,(DE)
	59187	LD C,A
	59188	LD B,0
	59190	AND A
	59191	SBC HL,BC
	59193	BIT 0,H
	59195	LD A,L
	59196	JP Z,Process_Player_Tracking_Enemy_0
	59199	NEG
Process_Player_Tracking_Enemy_0	59201	SRL A
	59203	SRL A
	59205	SRL A
	59207	SRL A
	59209	SRL A
	59211	BIT 0,H
	59213	JP Z,Process_Player_Tracking_Enemy_Face
	59216	NEG
Process_Player_Tracking_Enemy_Face	59218	LD B,A	Store the scaled Y nudge in B and X nudge in C; step back to the entity facing byte.
	59219	EX AF,AF'
	59220	LD C,A
	59221	EX DE,HL
	59222	DEC HL
	59223	DEC HL
	59224	LD A,(HL)
	59225	CP 26
	59227	JP Z,Process_Player_Tracking_Enemy_Freeze	Read the facing byte; if 26 jump to Process_Player_Tracking_Enemy_Freeze; otherwise test a 1-in-8192 random chance (Generate_Random_Byte twice, masked to 31 and 63) to set the facing to 26 (freeze).
	59230	CALL Generate_Random_Byte
	59233	AND 31
	59235	JP NZ,Process_Player_Tracking_Enemy_Move
	59238	CALL Generate_Random_Byte
	59241	AND 63
	59243	JP NZ,Process_Player_Tracking_Enemy_Move
	59246	LD (HL),26
	59248	JP Process_Player_Tracking_Enemy_Move
Process_Player_Tracking_Enemy_Freeze	59251	LD A,B	Facing is 26 (frozen): negate both velocity components; test a 1-in-256 chance to promote the facing to 31 (thaw).
	59252	NEG
	59254	LD B,A
	59255	LD A,C
	59256	NEG
	59258	LD C,A
	59259	CALL Generate_Random_Byte
	59262	CP 240
	59264	JP NZ,Process_Player_Tracking_Enemy_Move
	59267	LD (HL),31
Process_Player_Tracking_Enemy_Move	59269	INC HL	Apply the Y nudge to the entity Y position; clamp to 16-173 and write back.
	59270	LD A,C
	59271	ADD A,(HL)
	59272	CP 16
	59274	JP C,Process_Player_Tracking_Enemy_Move_X
	59277	CP 173
	59279	JP NC,Process_Player_Tracking_Enemy_Move_X
	59282	LD (HL),A
Process_Player_Tracking_Enemy_Move_X	59283	INC HL	Apply the X nudge to the entity X position; clamp to 8-239 and write back.
	59284	LD A,B
	59285	ADD A,(HL)
	59286	CP 8
	59288	JP C,Process_Player_Tracking_Enemy_Draw
	59291	CP 239
	59293	JP NC,Process_Player_Tracking_Enemy_Draw
	59296	LD (HL),A
Process_Player_Tracking_Enemy_Draw	59297	PUSH HL	Stash HL, step back two bytes, set colour INK: CYAN, PAPER: BLACK (BRIGHT) in alternate B, draw the entity via Draw_Entity_Sprite, restore HL, and advance via Process_Cluster_Entity_Next.
	59298	DEC HL
	59299	DEC HL
	59300	EXX
	59301	LD B,69
	59303	EXX
	59304	CALL Draw_Entity_Sprite
	59307	POP HL
	59308	JP Process_Cluster_Entity_Next