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(use-modules (chickadee)
(chickadee math vector)
(chickadee math rect)
(chickadee graphics color)
(chickadee graphics font)
(chickadee graphics tiled)
(ice-9 format)
(ice-9 match)
(srfi srfi-11))
(define map #f)
(define prev-camera (vec2 0.0 0.0))
(define camera (vec2 0.0 0.0))
(define render-camera (vec2 0.0 0.0))
(define text-position (vec2 4.0 4.0))
(define text "0, 0")
(define (stats-message)
(format #f "fps: ~1,2f"
(/ 1.0 avg-frame-time)))
(define start-time 0.0)
(define avg-frame-time 16)
(define stats-text (stats-message))
(define stats-text-pos (vec2 4.0 464.0))
(define last-update start-time)
(define scroll-speed 6.0)
(define (load)
(set! map (load-tile-map "maps/example.tmx")))
(define (draw alpha)
;; Linearly interpolate between the current camera position and the
;; previous camera position based on the alpha value. This makes
;; the scrolling appear much smoother because the Chickadee game
;; loop does not render in lock-step with updates.
(let ((beta (- 1.0 alpha)))
(set-vec2-x! render-camera
(+ (* (vec2-x camera) alpha)
(* (vec2-x prev-camera) beta)))
(set-vec2-y! render-camera
(+ (* (vec2-y camera) alpha)
(* (vec2-y prev-camera) beta))))
(draw-tile-map map #:camera render-camera)
(draw-text text text-position #:color black)
(draw-text stats-text stats-text-pos #:color black)
(let ((current-time (elapsed-time)))
(set! avg-frame-time
(+ (* (- current-time start-time) 0.1)
(* avg-frame-time 0.9)))
(set! start-time current-time)
(when (>= (- current-time last-update) 1000)
(set! stats-text (stats-message))
(set! last-update current-time))))
(define (update dt)
(vec2-copy! camera prev-camera)
(set-vec2-x! camera
(+ (vec2-x camera)
(if (key-pressed? 'right) scroll-speed 0.0)
(if (key-pressed? 'left) (- scroll-speed) 0.0)))
(set-vec2-y! camera
(+ (vec2-y camera)
(if (key-pressed? 'up) scroll-speed 0.0)
(if (key-pressed? 'down) (- scroll-speed) 0.0))))
(define (key-press key modifiers repeat?)
(match key
((or 'escape 'q) (abort-game))
(_ #t)))
(define (mouse-move x y x-rel y-rel buttons)
(let-values (((tx ty) (point->tile map (- x (vec2-x camera)) (- y (vec2-y camera)))))
(set! text (format #f "~d, ~d" tx ty))))
(run-game #:window-width 640
#:window-height 480
#:window-title "tile map demo"
#:load load
#:draw draw
#:update update
#:key-press key-press
#:mouse-move mouse-move)
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