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(import scheme
(chicken base)
(chicken random)
(only srfi-1 filter)
(prefix sdl2 "sdl2:")
(prefix sdl2-ttf "ttf:")
(prefix sdl2-image "img:")
downstroke/engine
downstroke/world
downstroke/physics
downstroke/input
downstroke/entity
downstroke/assets
downstroke/sound)
(define *frame-count* 0)
(define (make-bullet px py)
(list #:type 'bullet #:x px #:y py #:width 4 #:height 8 #:vx 0 #:vy -6))
(define (make-enemy rx)
(list #:type 'enemy #:x rx #:y 0 #:width 16 #:height 16 #:vx 0 #:vy 2))
(define (make-player)
(list #:type 'player #:x 280 #:y 360 #:width 16 #:height 16 #:vx 0 #:vy 0))
(define (entities-overlap? a b)
(aabb-overlap?
(entity-ref a #:x 0) (entity-ref a #:y 0)
(entity-ref a #:width 0) (entity-ref a #:height 0)
(entity-ref b #:x 0) (entity-ref b #:y 0)
(entity-ref b #:width 0) (entity-ref b #:height 0)))
(define (find-dead entities)
(let ((bullets (filter (lambda (e) (eq? (entity-ref e #:type) 'bullet)) entities))
(enemies (filter (lambda (e) (eq? (entity-ref e #:type) 'enemy)) entities))
(dead '()))
(for-each
(lambda (b)
(for-each
(lambda (en)
(when (entities-overlap? b en)
(set! dead (cons b (cons en dead)))))
enemies))
bullets)
dead))
(define *game*
(make-game
title: "Demo: Shoot-em-up" width: 600 height: 400
preload: (lambda (game)
(init-audio!)
(load-sounds! '((shoot . "demo/assets/jump.wav"))))
create: (lambda (game)
(game-scene-set! game
(make-scene
entities: (list (make-player))
tilemap: #f
camera: (make-camera x: 0 y: 0)
tileset-texture: #f
camera-target: #f)))
update: (lambda (game dt)
(let* ((input (game-input game))
(scene (game-scene game))
(entities (scene-entities scene))
(player (car (filter (lambda (e) (eq? (entity-ref e #:type) 'player))
entities))))
(set! *frame-count* (+ *frame-count* 1))
;; Move player
(let* ((player (entity-set player #:vx
(cond ((input-held? input 'left) -4)
((input-held? input 'right) 4)
(else 0))))
(player (apply-velocity-x player))
(player (entity-set player #:x
(max 0 (min 584 (entity-ref player #:x 0))))))
;; Fire bullet
(when (input-pressed? input 'a)
(play-sound 'shoot)
(scene-add-entity scene
(make-bullet (+ (entity-ref player #:x 0) 6) 340)))
;; Spawn enemy every 60 frames
(when (zero? (modulo *frame-count* 60))
(scene-add-entity scene
(make-enemy (+ 20 (* (pseudo-random-integer 28) 20)))))
;; Update player in scene
(scene-entities-set! scene
(cons player
(filter (lambda (e) (not (eq? (entity-ref e #:type) 'player)))
(scene-entities scene)))))
;; Move non-player entities
(scene-update-entities scene
(lambda (e)
(if (eq? (entity-ref e #:type) 'player)
e
(entity-set
(entity-set e #:x (+ (entity-ref e #:x 0) (entity-ref e #:vx 0)))
#:y (+ (entity-ref e #:y 0) (entity-ref e #:vy 0))))))
;; Remove collisions
(let ((dead (find-dead (scene-entities scene))))
(scene-filter-entities scene
(lambda (e) (not (memq e dead)))))
;; Remove out-of-bounds
(scene-filter-entities scene
(lambda (e)
(let ((y (entity-ref e #:y 0)))
(or (eq? (entity-ref e #:type) 'player)
(and (> y -20) (< y 420))))))))
render: (lambda (game)
(let* ((renderer (game-renderer game))
(scene (game-scene game))
(entities (scene-entities scene)))
(for-each
(lambda (e)
(let ((type (entity-ref e #:type 'unknown))
(x (inexact->exact (floor (entity-ref e #:x 0))))
(y (inexact->exact (floor (entity-ref e #:y 0))))
(w (entity-ref e #:width 16))
(h (entity-ref e #:height 16)))
(set! (sdl2:render-draw-color renderer)
(case type
((player) (sdl2:make-color 255 255 255 255))
((bullet) (sdl2:make-color 255 255 0 255))
((enemy) (sdl2:make-color 255 50 50 255))
(else (sdl2:make-color 100 100 100 255))))
(sdl2:render-fill-rect! renderer
(sdl2:make-rect x y w h))))
entities)))))
(game-run! *game*)
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