Routines
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E2C8: Pick Random Spawn Position
Used by the routines at Spawn_Horizontal_Wave_Enemies, Spawn_Tracked_Enemy_Entities and Spawn_Wall_Bouncing_Enemies.
Generates a random Y coordinate in the range 10-A7 and a random X coordinate in the range 08-E7 writing both to *HL with initial velocities 10/10 then tests whether the chosen position overlaps the player spawn zone via HitTestBounds8AtHL; retries the whole selection if it does. Called from Spawn_Horizontal_Wave_Enemies and Spawn_Wall_Bouncing_Enemies.
Pick_Random_Spawn_Position_Y E2C8 CALL Generate_Random_Byte Generate random bytes until a valid Y coordinate (10-A7) is found and write it to *HL.
E2CB CP $10
E2CD JP C,Pick_Random_Spawn_Position_Y
E2D0 CP $A8
E2D2 JP NC,Pick_Random_Spawn_Position_Y
E2D5 LD (HL),A
E2D6 INC HL
Pick_Random_Spawn_Position_X E2D7 CALL Generate_Random_Byte Generate random bytes until a valid X coordinate (08-E7) is found and write it to *HL.
E2DA CP $08
E2DC JP C,Pick_Random_Spawn_Position_X
E2DF CP $E8
E2E1 JP NC,Pick_Random_Spawn_Position_X
E2E4 LD (HL),A
E2E5 INC HL Write initial Y and X velocities (10 each) to the entity record.
E2E6 LD (HL),$10
E2E8 INC HL
E2E9 LD (HL),$10
E2EB DEC HL Step back three bytes and set the player spawn area address in alternate HL via Entity_Spawn_Handler.
E2EC DEC HL
E2ED DEC HL
E2EE EXX
E2EF LD HL,$D1C7
E2F2 EXX
E2F3 CALL HitTestBounds8AtHL Test whether the position overlaps the player spawn zone via HitTestBounds8AtHL; return if clear.
E2F6 RET C
E2F7 DEC HL Retry the whole position selection from Pick_Random_Spawn_Position_Y if it overlaps.
E2F8 DEC HL
E2F9 DEC HL
E2FA JP Pick_Random_Spawn_Position_Y
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