9028dd031c
Implement four ghosts (Blinky, Pinky, Inky, Clyde) with authentic Pac-Man AI: Blinky chases directly, Pinky targets 2 tiles ahead (with original up-direction bug), Inky uses vector doubling from Blinky, Clyde switches to scatter within 8-tile radius. Includes chase/scatter mode cycling, ghost house exit with staggered delays, directional sprite rendering with animation, and ghost-pacman collision detection. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
95 lines
3.8 KiB
Racket
95 lines
3.8 KiB
Racket
#lang r7rs
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Ghost ADT ;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; A ghost has a position, direction, movement mode, and type identity.
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;; The targeting AI is handled by the level — this ADT only stores state.
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;; Each ghost instance represents one of the four ghosts (Blinky, Inky,
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;; Pinky, Clyde). Contains NO graphics code.
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(define-library (pacman-project adt ghost)
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(import (scheme base)
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(pacman-project adt position))
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(export make-ghost)
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(begin
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;; make-ghost :: symbol, number, number, number, number, number -> ghost
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;; Creates a ghost of the given type at start-row/col with a scatter
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;; corner target and a house exit delay (0 = starts outside).
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(define (make-ghost ghost-type start-row start-col
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scatter-row scatter-col exit-delay)
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(let ((position (make-position start-row start-col))
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(direction 'left)
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(mode (if (= exit-delay 0) 'scatter 'in-house))
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(scatter-target (make-position scatter-row scatter-col))
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(house-timer exit-delay)
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(movement-timer 0)
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(reverse-queued? #f))
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;; direction! :: symbol -> /
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(define (direction! new-dir)
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(set! direction new-dir))
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;; mode! :: symbol -> /
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;; Sets the ghost mode. When switching between chase/scatter,
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;; the ghost must reverse direction (queued for next move).
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(define (mode! new-mode)
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(when (and (not (eq? mode new-mode))
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(not (eq? mode 'in-house))
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(not (eq? new-mode 'in-house)))
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(set! reverse-queued? #t))
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(set! mode new-mode))
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;; move! :: number, number -> /
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(define (move! delta-row delta-col)
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((position 'row!) (+ (position 'row) delta-row))
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((position 'col!) (+ (position 'col) delta-col)))
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;; consume-reverse! :: -> boolean
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;; Returns #t and clears the flag if a reverse was queued.
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(define (consume-reverse!)
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(if reverse-queued?
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(begin (set! reverse-queued? #f) #t)
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#f))
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;; update-house-timer! :: number -> /
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;; Decreases house timer. When it reaches 0, ghost exits.
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(define (update-house-timer! delta-time)
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(when (eq? mode 'in-house)
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(set! house-timer (- house-timer delta-time))
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(when (<= house-timer 0)
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(set! mode 'scatter))))
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;; reset-movement-timer! :: -> /
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(define (reset-movement-timer!)
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(set! movement-timer 0))
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;; advance-movement-timer! :: number -> number
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;; Returns updated movement timer value.
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(define (advance-movement-timer! delta-time)
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(set! movement-timer (+ movement-timer delta-time))
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movement-timer)
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;; dispatch-ghost :: symbol -> any
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(define (dispatch-ghost msg)
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(cond ((eq? msg 'position) position)
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((eq? msg 'direction) direction)
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((eq? msg 'direction!) direction!)
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((eq? msg 'type) ghost-type)
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((eq? msg 'mode) mode)
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((eq? msg 'mode!) mode!)
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((eq? msg 'move!) move!)
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((eq? msg 'scatter-target) scatter-target)
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((eq? msg 'in-house?) (eq? mode 'in-house))
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((eq? msg 'consume-reverse!) consume-reverse!)
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((eq? msg 'update-house-timer!) update-house-timer!)
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((eq? msg 'movement-timer) movement-timer)
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((eq? msg 'advance-movement-timer!) advance-movement-timer!)
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((eq? msg 'reset-movement-timer!) reset-movement-timer!)
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(else (error "Ghost ADT -- Unknown message:" msg))))
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dispatch-ghost))))
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