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Easing in and out of center using a sin function

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Amy Grinn 2025-01-23 13:39:39 -05:00
parent f67eb80910
commit 0b39ba733d
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GPG key ID: 6B558BED1DCF3192
1 changed files with 92 additions and 55 deletions
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game.scm
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@ -281,6 +281,8 @@
(set-level! *level-idx*) (set-level! *level-idx*)
(media-play audio:bg-music))))) (media-play audio:bg-music)))))
(define text-offset-y (* 0.75 tile-height))
;; Menu types ;; Menu types
(define-record-type <menu> (define-record-type <menu>
@ -393,10 +395,10 @@
;; Credits ;; Credits
(define credits-margin 40.0) ;; pixels (define credits-margin 0.0) ;; lines
(define credits-pace 30.0) ;; frames per line (inverse speed) (define credits-pace 15.0) ;; ticks per line (inverse speed)
(define credits-start (+ game-height (* 0.75 tile-height))) (define credits-start (+ game-height text-offset-y))
(define credits-end (* 0.75 tile-height)) (define credits-end text-offset-y)
(define line-height (define line-height
(let ((lh #f)) (let ((lh #f))
@ -407,7 +409,7 @@
(set! lh (set! lh
(* (+ (text-metrics-actual-bounding-box-ascent metrics) (* (+ (text-metrics-actual-bounding-box-ascent metrics)
(text-metrics-actual-bounding-box-descent metrics)) (text-metrics-actual-bounding-box-descent metrics))
1.2)))) 1.25))))
lh))) lh)))
(define-record-type <credit> (define-record-type <credit>
@ -421,13 +423,13 @@
(define* (make-credit #:key (lines 1) (define* (make-credit #:key (lines 1)
(draw (lambda (y) #f)) (draw (lambda (y) #f))
(update (lambda (y) #f)) (update (lambda (t) #f))
(on-enter (lambda () #f)) (on-enter (lambda () #f))
(on-leave (lambda () #f))) (on-leave (lambda () #f)))
(_make-credit lines draw update on-enter on-leave)) (_make-credit lines draw update on-enter on-leave))
(define* (make-credit-group #:rest credits) (define* (make-credit-group #:rest credits)
(let ((accumulate (lambda* (accessor #:key (init 0) preproc) (let ((accumulate (lambda* (accessor #:key (init 0.0) preproc)
(fold (lambda (c sum) (fold (lambda (c sum)
(when preproc ((preproc c) sum)) (when preproc ((preproc c) sum))
(+ sum (accessor c))) (+ sum (accessor c)))
@ -459,67 +461,102 @@
(make-credit-text text) (make-credit-text text)
(make-credit-text (make-string (string-length text) #\-)))) (make-credit-text (make-string (string-length text) #\-))))
(define* (make-credit-centering credit #:key (padding 6.0) (fade 1.0)) (define* (make-credit-centering credit #:key (padding 6.0) (easing 4.0)
(let* ((offset 0.0) (on-enter-center (lambda () #f))
(center (+ (/ (- game-height (credit-height credit)) 2) (on-leave-center (lambda () #f)))
(* 0.75 tile-height))) (let* ((pi 3.14159)
(beg (+ center (* (line-height) fade))) (offset 0.0)
(end (- center (* (line-height) (+ padding (* 3 fade)))))) (speed (/ (line-height) credits-pace))
(center (/ (- (+ credits-start credits-end) (credit-height credit)) 2.0))
(ease-height (* (line-height) easing))
(ease-speed (lambda (y) (* speed (sin (/ y ease-height)))))
;; Amount that credits scroll up during easing
(ease-travel (* ease-height (/ pi 2.0)))
;; Start below center so that it eases right into the center
(beg (+ center (- ease-travel ease-height)))
(beg-mid (- beg ease-travel))
(end-mid (- beg-mid (* (line-height) padding)))
(end (- end-mid ease-travel)))
(make-credit (make-credit
#:lines (+ padding (* 2 fade) (credit-lines credit)) #:lines (+ padding (* 2 easing) (credit-lines credit))
#:draw (lambda (y) ((credit-draw credit) (+ y offset))) #:draw (lambda (y) ((credit-draw credit) (+ y offset)))
#:update #:update
;; Remember that y is decreasing as credits rise up the screen
;; toward y=0, so the comparators might seem to be flipped but
;; that's how they need to be.
(lambda (y) (lambda (y)
(when (<= y beg) (when (and (<= y beg) (> y end))
(cond (cond
((> y (- center (* (line-height) fade))) ((> y beg-mid)
;; Accelerate ;; Accelerate
(set! offset (+ offset (/ (- beg y) 2 fade credits-pace)))) (set! offset (+ offset (ease-speed (- beg y)))))
((> y (- center (* (line-height) (+ fade padding)))) ((> y end-mid)
;; Match speed ;; Match speed
(set! offset (+ offset (/ (line-height) credits-pace)))) (set! offset (+ offset speed))
((> y end) (when on-enter-center
;; Decelarate (on-enter-center)
(set! offset (+ offset (/ (- y end) 2 fade credits-pace)))))) (set! on-enter-center #f)))
(else
;; Decelerate
(when on-leave-center
(on-leave-center)
(set! on-leave-center #f))
(set! offset (+ offset (ease-speed (- y end)))))))
;; Call on-leave-center even if no easing is used
(when (and (<= y end) on-leave-center)
(on-leave-center)
(set! on-leave-center #f))
((credit-update credit) (+ y offset))) ((credit-update credit) (+ y offset)))
#:on-enter (credit-on-enter credit) #:on-enter (credit-on-enter credit)
#:on-leave (credit-on-leave credit)))) #:on-leave (credit-on-leave credit))))
(define (make-credits) (define (make-credits)
(vector (make-credit-group (vector (make-credit-centering
(make-credit-group
(make-credit-text "Phew, you made it!") (make-credit-text "Phew, you made it!")
(make-credit-text "Time to relax.")) (make-credit-text "Time to relax.")))
(make-credit-centering (make-credit-centering
(make-credit-group (make-credit-group
(make-credit-text "Cirkoban was made by the") (make-credit-text "Cirkoban was made by the")
(make-credit-text "Spritely Institute"))) (make-credit-text "Spritely Institute")))
(make-credit-text "https://spritely.institute") (make-credit-centering
(make-credit-text "https://spritely.institute"))
(make-credit-centering
(make-credit-group (make-credit-group
(make-credit-underline "Game Design") (make-credit-underline "Game Design")
(make-credit-text "Christine Lemmer-Webber")) (make-credit-text "Christine Lemmer-Webber")))
(make-credit-centering
(make-credit-group (make-credit-group
(make-credit-underline "Level Design") (make-credit-underline "Level Design")
(make-credit-text "Christine Lemmer-Webber") (make-credit-text "Christine Lemmer-Webber")
(make-credit-text "Juliana Sims") (make-credit-text "Juliana Sims")
(make-credit-text "David Thompson")) (make-credit-text "David Thompson"))
#:on-enter-center (lambda () (pk "Level Design centering!!"))
#:on-leave-center (lambda () (pk "Level Design leaving center!!")))
(make-credit-centering
(make-credit-group (make-credit-group
(make-credit-underline "Pixel Art") (make-credit-underline "Pixel Art")
(make-credit-text "Christine Lemmer-Webber")) (make-credit-text "Christine Lemmer-Webber"))
#:easing 0
#:on-enter-center (lambda () (pk "Pixel Art centering!!"))
#:on-leave-center (lambda () (pk "Pixel Art leaving center!!")))
(make-credit-centering
(make-credit-group (make-credit-group
(make-credit-underline "Music") (make-credit-underline "Music")
(make-credit-text "EncryptedWhispers") (make-credit-text "EncryptedWhispers")
(make-credit-text "Christine Lemmer-Webber")) (make-credit-text "Christine Lemmer-Webber")))
(make-credit-centering
(make-credit-group (make-credit-group
(make-credit-underline "Programming") (make-credit-underline "Programming")
(make-credit-text "Juliana Sims") (make-credit-text "Juliana Sims")
(make-credit-text "David Thompson") (make-credit-text "David Thompson")
(make-credit-text "Amy Grinn")) (make-credit-text "Amy Grinn")))
(make-credit-centering
(make-credit-group (make-credit-group
(make-credit-underline "Other") (make-credit-underline "Other")
(make-credit-text "monogram font by datagoblin")) (make-credit-text "monogram font by datagoblin")))
(make-credit-centering (make-credit-centering
(make-credit-text "Thank you for playing!") (make-credit-text "Thank you for playing!"))))
#:fade 1)))
(define-record-type <credits> (define-record-type <credits>
(make-credits-state credits top first-visible-index next-visible-index) (make-credits-state credits top first-visible-index next-visible-index)
@ -572,7 +609,8 @@
(<= y credits-start)) (<= y credits-start))
(let ((c (vector-ref (credits) i))) (let ((c (vector-ref (credits) i)))
((credit-draw c) y) ((credit-draw c) y)
(lp (1+ i) (+ y (credit-height c) credits-margin)))))) (lp (1+ i) (+ y (credit-height c) (* (line-height)
credits-margin)))))))
(define (update-credits!) (define (update-credits!)
(let ((i (credits-first-visible-index))) (let ((i (credits-first-visible-index)))
@ -588,12 +626,12 @@
((credit-on-enter c)) ((credit-on-enter c))
(set-credits-next-visible-index! i)) (set-credits-next-visible-index! i))
((credit-update c) y) ((credit-update c) y)
(lp (1+ i) (+ y (credit-height c) credits-margin))))) (lp (1+ i) (+ y (credit-height c) (* (line-height) credits-margin))))))
;; Remove credits as they leave the screen ;; Remove credits as they leave the screen
(let* ((c (vector-ref (credits) i)) (let* ((c (vector-ref (credits) i))
(bottom (+ (credits-top) (credit-height c)))) (bottom (+ (credits-top) (credit-height c))))
(when (< bottom credits-end) (when (< bottom credits-end)
(set-credits-top! (+ bottom credits-margin)) (set-credits-top! (+ bottom (* (line-height) credits-margin)))
(set-credits-first-visible-index! (1+ i)) (set-credits-first-visible-index! (1+ i))
((credit-on-leave c)))) ((credit-on-leave c))))
;; Advance credits ;; Advance credits
@ -946,7 +984,6 @@
;; + num menu items + 1 for ellipses if num items is too big ;; + num menu items + 1 for ellipses if num items is too big
;; + the y padding again ;; + the y padding again
(let* ((padding-y 1) (let* ((padding-y 1)
(text-offset-y (* 0.75 tile-height))
(width 8.0) (width 8.0)
(num-items (vector-length (menu-items (current-menu)))) (num-items (vector-length (menu-items (current-menu))))
(height (+ 2 ;; Menu title + back/ellipses (height (+ 2 ;; Menu title + back/ellipses