Routines
Prev: C440 Up: Map Next: C4C8
C4A3: Test Player In Room
Used by the routines at HandlePickupAndDrop and HandlePlayerLegs.
Tests whether the player is inside the room. The distance from the middle of the room (80) has to be smaller than the distance to the wall, less the width of the player along x and less the depth of the player along y.
Input
IX The address of the object
Output
F Carry flag set if the player is inside the room
Limits from the wall distances.
TestPlayerInRoom C4A3 LD HL,($A71D) Fetch the limits of the room, RoomSizeX along x and RoomSizeY along y.
Take the half size along x off the limit along x.
C4A6 LD A,L Copy the distance along x to A.
C4A7 SUB (IX+$04) Subtract the width of the player.
C4AA LD L,A Store the limit along x in L.
Take the half size along y off the limit along y.
C4AB LD A,H Copy the distance along y to A.
C4AC SUB (IX+$05) Subtract the depth of the player.
C4AF LD H,A Store the limit along y in H.
Compare the x distance from the middle.
C4B0 LD A,(IX+$01) Fetch the x position of the object.
Take away the middle of the room, 80, and jump to TestPlayerInRoom_LimitX if the distance is not negative.
C4B3 SUB $80 Subtract 80.
C4B5 JP P,TestPlayerInRoom_LimitX Jump to TestPlayerInRoom_LimitX if the sign flag is clear.
C4B8 NEG Negate A.
TestPlayerInRoom_LimitX C4BA CP L Return if the player is outside along x.
C4BB RET NC
Compare the y distance from the middle.
C4BC LD A,(IX+$02) Fetch the y position of the object.
Take away the middle of the room, 80, and jump to TestPlayerInRoom_LimitY if the distance is not negative.
C4BF SUB $80 Subtract 80.
C4C1 JP P,TestPlayerInRoom_LimitY Jump to TestPlayerInRoom_LimitY if the sign flag is clear.
C4C4 NEG Negate A.
TestPlayerInRoom_LimitY C4C6 CP H Compare it with the limit along y.
C4C7 RET Return.
View the equivalent code in;
Prev: C440 Up: Map Next: C4C8