Routines
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37068: Check Player In Range
Used by the routines at HandlerDoorExit, CheckDoorKey and FallThroughTrapdoor.
Checks whether the player is close to the entity of a door. It is only checked when the player is a character and the bottom four bits of offset 2 of the player are zero. The player is in range when it is to the right of the position of the entity by less than the range along the X axis, and above it by less than the range along the Y axis. The range along the X axis is halved if the attribute of the entity is bright, and the range along the Y axis is halved if it is not.
Input
B The range along the Y axis
C The range along the X axis
IX The entity
Output
F The carry flag is set if the player is in range
CheckPlayerInRange 37068 LD A,(60050) Fetch offset 2 of the player.
37071 AND %00001111 Keep only bits 0-3.
37073 RET NZ Return if they are not all zero.
37074 LD A,(60048) Fetch the sprite ID of the player from Player.
37077 DEC A Subtract one to get the ID that starts at zero.
37078 CP 48 Return if the player is not a character.
37080 RET NC
37081 BIT 6,(IX+5) Jump to CheckPlayerInRange_X if the attribute of the entity is not bright.
37085 JR Z,CheckPlayerInRange_X
37087 SRL C Halve the range along the X axis.
CheckPlayerInRange_X 37089 LD A,(60051) Fetch the X position of the player from 60051.
37092 SUB (IX+3) Subtract the X position of the entity.
37095 CP C Return if the player is not in range.
37096 RET NC
37097 BIT 6,(IX+5) Jump to CheckPlayerInRange_Y if the attribute of the entity is bright.
37101 JR NZ,CheckPlayerInRange_Y
37103 SRL B Halve the range along the Y axis.
CheckPlayerInRange_Y 37105 LD A,(60052) Fetch the Y position of the player from 60052.
37108 SUB (IX+4) Subtract the Y position of the entity.
37111 NEG Negate the result.
37113 CP B Compare it with the range.
37114 RET Return.
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