Routines
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45032: Move Actor
Used by the routines at HandlerHippoWarthog, HandlerGuardian, HandlerWulf, HandlerTribesman, HandlerRhino, PlayerMovement and GamePlay_Start.
Works out the new position of an actor from its velocities. The velocities are signed and in units of one sixteenth of a pixel, so they are first scaled by GetWholePixels. The new position is returned in E and D and is not written to the actor record.
If the actor would move off the screen it is moved to the neighbouring room instead, using EnterRoomLeft (left), EnterRoomRight (right), EnterRoomBelow (below) or EnterRoomAbove (above). The top of the screen is at 40 the bottom at 192 and the width of the actor (held in Actor_Width) is taken into account at the right.
Input
IX Actor record
Output
D New Y position
E New X position
MoveActor 45032 LD A,(IX+1) Store the room of the actor in Moved_Actor_Room.
45035 LD (38571),A
45038 LD D,(IX+4) Fetch the Y position of the actor into D.
45041 LD A,(IX+6) Fetch the X velocity of the actor.
45044 CALL GetWholePixels Convert the X velocity to whole pixels.
45047 AND A Jump to MoveActorLeft if the actor is moving left.
45048 JP M,MoveActorLeft
The actor is moving right.
45051 ADD A,(IX+3) Add the X position of the actor.
45054 LD E,A Stash the new X position in E.
45055 LD A,(38573) Fetch the width of the actor from Actor_Width.
45058 ADD A,E Add the new X position to find the right edge of the actor.
45059 JP C,EnterRoomRight Jump to EnterRoomRight if the actor has left the screen on the right.
This entry point is used by the routine at MoveActorLeft.
Now move the actor up or down.
MoveActor_Vertical 45062 LD A,(IX+7) Fetch the Y velocity of the actor.
45065 CALL GetWholePixels Convert the Y velocity to whole pixels.
45068 AND A Jump to MoveActorUp if the actor is moving up.
45069 JP M,MoveActorUp
45072 ADD A,(IX+4) Add the Y position of the actor.
45075 LD D,A Stash the new Y position in D.
45076 CP 192 Jump to EnterRoomBelow if the actor has left the screen at the bottom.
45078 JP NC,EnterRoomBelow
45081 RET Return.
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