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Implement automatic Pac-Man movement with queued direction turning

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Pac-Man now moves automatically in its current direction every
pacman-speed-ms (200ms). Arrow keys queue a desired turn direction
instead of moving directly. Each movement tick:

1. Try the queued direction — if passable, turn and move that way
2. Otherwise keep moving in the current direction
3. Stop only when hitting a wall (no direction change)

New internal state:
- queued-direction: the direction the player wants to turn next
- movement-timer: accumulates delta-time, triggers move at interval

New helper:
- can-move?: checks if a direction is passable (no wall/locked door)

Changed behavior:
- key-press! now sets queued-direction instead of calling move-pacman!
- update! now drives movement via advance-pacman! on a timer
- move-pacman! no longer checks time-up? (advance-pacman! handles it)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
This commit is contained in:
joren
2026-03-23 11:15:46 +01:00
parent 39a91a5aa0
commit 4c98ca61c5
1 changed files with 82 additions and 41 deletions
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73
pacman-project/adt/level.rkt
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@@ -4,9 +4,11 @@
;; Level ADT ;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Contains all game logic: Pac-Man movement, collision detection, coin/key
;; pickup, door opening, teleportation, pause, and time management.
;; Contains NO graphics code.
;; Contains all game logic: automatic Pac-Man movement, collision detection,
;; coin/key pickup, door opening, teleportation, pause, and time management.
;; Pac-Man moves automatically in its current direction. Arrow keys queue a
;; desired turn direction, which is applied at the next movement tick if the
;; path is clear. Contains NO graphics code.
(define-library (pacman-project adt level)
(import (scheme base)
@@ -29,7 +31,9 @@
(key #f)
(score (make-score))
(timer (make-timer))
(paused? #f))
(paused? #f)
(queued-direction #f)
(movement-timer 0))
;; Initialize key after maze is created.
(set! key (make-key maze))
@@ -47,6 +51,23 @@
((eq? direction 'down) (cons 1 0))
(else (cons 0 0))))
;; can-move? :: symbol -> boolean
;; Checks if Pac-Man can move in the given direction (no wall or
;; locked door blocking the way).
(define (can-move? direction)
(let* ((delta (direction->delta direction))
(current-pos (pacman 'position))
(next-row (+ (current-pos 'row) (car delta)))
(next-col (+ (current-pos 'col) (cdr delta))))
(cond
;; Teleportation tunnels are always passable.
((or (< next-col 0) (>= next-col (maze 'cols))) #t)
;; Walls block.
(((maze 'wall?) next-row next-col) #f)
;; Doors block unless the key has been taken.
(((maze 'door?) next-row next-col) (key 'taken?))
(else #t))))
;;
;; Coin logic
;;
@@ -88,9 +109,9 @@
;;
;; move-pacman! :: symbol -> /
;; Moves Pac-Man in the given direction with all game rules.
;; Moves Pac-Man one step in the given direction, handling collisions,
;; teleportation, and item pickup.
(define (move-pacman! direction)
(when (not ((timer 'time-up?)))
(let* ((delta (direction->delta direction))
(delta-row (car delta))
(delta-col (cdr delta))
@@ -98,7 +119,7 @@
(next-row (+ (current-pos 'row) delta-row))
(next-col (+ (current-pos 'col) delta-col)))
;; Update direction for the draw layer.
;; Update facing direction for the draw layer.
((pacman 'direction!) direction)
(cond
@@ -106,7 +127,7 @@
((or (< next-col 0) (>= next-col (maze 'cols)))
(teleport-horizontal! next-row next-col))
;; Door: only open if key has been taken.
;; Door: open it if key has been taken.
(((maze 'door?) next-row next-col)
(when (key 'taken?)
((maze 'remove-door!) next-row next-col)))
@@ -120,7 +141,22 @@
(((maze 'key?) next-row next-col)
(pick-up-key! next-row next-col))
(((maze 'coin?) next-row next-col)
(eat-coin! next-row next-col)))))))))
(eat-coin! next-row next-col))))))))
;; advance-pacman! :: -> /
;; Called every movement tick. Tries the queued direction first; if
;; that path is blocked, continues in the current direction.
(define (advance-pacman!)
(when (not ((timer 'time-up?)))
(let ((current-dir (pacman 'direction)))
;; Try the queued direction first.
(cond
((and queued-direction (can-move? queued-direction))
(move-pacman! queued-direction)
(set! queued-direction #f))
;; Otherwise keep moving in the current direction.
((can-move? current-dir)
(move-pacman! current-dir))))))
;;
;; Pause logic
@@ -135,26 +171,31 @@
;;
;; key-press! :: symbol -> /
;; Processes a key press.
;; Processes a key press. Arrow keys queue a desired direction.
(define (key-press! pressed-key)
(cond
((eq? pressed-key 'escape) (toggle-pause!))
((not paused?)
(cond
((eq? pressed-key 'right) (move-pacman! 'right))
((eq? pressed-key 'left) (move-pacman! 'left))
((eq? pressed-key 'up) (move-pacman! 'up))
((eq? pressed-key 'down) (move-pacman! 'down))))))
((eq? pressed-key 'right) (set! queued-direction 'right))
((eq? pressed-key 'left) (set! queued-direction 'left))
((eq? pressed-key 'up) (set! queued-direction 'up))
((eq? pressed-key 'down) (set! queued-direction 'down))))))
;;
;; Update (game loop function)
;;
;; update! :: number -> /
;; Called each frame with elapsed milliseconds.
;; Called each frame with elapsed milliseconds. Advances the movement
;; timer and moves Pac-Man automatically when the interval elapses.
(define (update! delta-time)
(when (not paused?)
((timer 'decrease!) delta-time)))
((timer 'decrease!) delta-time)
(set! movement-timer (+ movement-timer delta-time))
(when (>= movement-timer pacman-speed-ms)
(advance-pacman!)
(set! movement-timer 0))))
;;
;; Dispatch