f251478dd6
Entities now move smoothly between tiles instead of snapping. Previous positions are tracked in pacman and ghost ADTs; the draw layer linearly interpolates between prev and current based on movement timer progress. Residual time is carried across movement ticks for consistent speed at varying frame rates. Teleportation and ghost house exits call sync-prev! to prevent cross-map interpolation artifacts. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
62 lines
2.3 KiB
Racket
62 lines
2.3 KiB
Racket
#lang r7rs
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Pac-Man ADT ;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Manages the logical state of the player: grid position, direction, and
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;; previous position for smooth rendering interpolation. Contains NO
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;; graphics code.
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(define-library (pacman-project adt pacman)
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(import (scheme base)
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(pacman-project adt position))
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(export make-pacman)
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(begin
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;; make-pacman :: number, number -> pacman
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;; Creates a Pac-Man object at the given start position (row, col).
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(define (make-pacman start-row start-col)
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(let ((position (make-position start-row start-col))
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(direction 'right)
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(prev-row start-row)
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(prev-col start-col))
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;; position! :: position -> /
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(define (position! new-position)
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(set! position new-position))
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;; direction! :: symbol -> /
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(define (direction! new-direction)
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(set! direction new-direction))
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;; move! :: number, number -> /
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;; Saves previous position, then moves by delta on the grid.
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(define (move! delta-row delta-col)
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(set! prev-row (position 'row))
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(set! prev-col (position '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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;; sync-prev! :: -> /
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;; Sets previous position to current. Call after teleportation
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;; to prevent interpolation across the map.
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(define (sync-prev!)
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(set! prev-row (position 'row))
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(set! prev-col (position 'col)))
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;; dispatch-pacman :: symbol -> any
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(define (dispatch-pacman msg)
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(cond ((eq? msg 'position) position)
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((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 'move!) move!)
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((eq? msg 'prev-row) prev-row)
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((eq? msg 'prev-col) prev-col)
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((eq? msg 'sync-prev!) sync-prev!)
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(else (error "Pac-Man ADT -- Unknown message:" msg))))
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dispatch-pacman))))
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