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Fix ghost and Pac-Man movement interpolation teleport #1

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Joren merged 1 commits from fix/ghost-movement into feature/ghosts 2026-03-23 12:40:06 +01:00
Conversation 0 Commits 1 Files Changed 1 +10 -13
1 changed files with 10 additions and 13 deletions
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23
pacman-project/adt/draw.rkt
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@@ -262,20 +262,18 @@
(+ a (* t (- b a))))
;; draw-pacman! :: pacman, number -> /
;; Draws Pac-Man with offset backward interpolation. Uses
;; lerp(prev, current, 0.5 + t/2) so the visual starts at the
;; midpoint (max 0.5 tile lag) and arrives at current by t=1.
;; No jumps on direction changes unlike forward extrapolation.
;; Draws Pac-Man with smooth backward interpolation. Uses
;; lerp(prev, current, t) so the visual smoothly transitions
;; from the previous tile strictly to the current tile by t=1.
(define (draw-pacman! pacman progress)
(let* ((pos (pacman 'position))
(row (pos 'row))
(col (pos 'col))
(prev-row (pacman 'prev-row))
(prev-col (pacman 'prev-col))
(t (min progress 1))
(factor (+ 0.5 (* 0.5 t)))
(render-row (lerp prev-row row factor))
(render-col (lerp prev-col col factor))
(t (max 0 (min progress 1)))
(render-row (lerp prev-row row t))
(render-col (lerp prev-col col t))
(direction (pacman 'direction)))
((pacman-sprite 'set-x!) (grid->pixel-x render-col))
((pacman-sprite 'set-y!) (grid->pixel-y render-row))
@@ -285,7 +283,7 @@
((eq? direction 'down) ((pacman-sprite 'rotate!) rotation-down)))))
;; draw-ghosts! :: list -> /
;; Updates all ghost sprite positions with offset backward interpolation.
;; Updates all ghost sprite positions with smooth backward interpolation.
(define (draw-ghosts! ghosts)
(for-each
(lambda (ghost ghost-draw)
@@ -294,10 +292,9 @@
(col (pos 'col))
(prev-row (ghost 'prev-row))
(prev-col (ghost 'prev-col))
(t (min (/ (ghost 'movement-timer) ghost-speed-ms) 1))
(factor (+ 0.5 (* 0.5 t)))
(render-row (lerp prev-row row factor))
(render-col (lerp prev-col col factor))
(t (max 0 (min (/ (ghost 'movement-timer) ghost-speed-ms) 1)))
(render-row (lerp prev-row row t))
(render-col (lerp prev-col col t))
(dir (ghost 'direction)))
((ghost-draw 'update!) render-row render-col dir)))
ghosts ghost-draw-states))