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(import scheme
(chicken base)
(chicken random)
(only srfi-1 filter any)
(only srfi-197 chain)
(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)
;; ── Constants ────────────────────────────────────────────────────────────────
(define +screen-width+ 600)
(define +screen-height+ 400)
(define +spawn-interval+ 60)
;; ── State ────────────────────────────────────────────────────────────────────
(define *frame-count* 0)
;; ── Entity factories ─────────────────────────────────────────────────────────
(define (make-player)
(list #:type 'player #:x 280 #:y 360
#:width 16 #:height 16 #:vx 0 #:vy 0))
(define (make-bullet x y)
(list #:type 'bullet #:x x #:y y
#:width 4 #:height 8 #:vx 0 #:vy -6))
(define (make-enemy x)
(list #:type 'enemy #:x x #:y 0
#:width 16 #:height 16 #:vx 0 #:vy 2))
;; ── Collision ────────────────────────────────────────────────────────────────
(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-type e) 'bullet)) entities))
(enemies (filter (lambda (e) (eq? (entity-type e) 'enemy)) entities)))
(filter (lambda (e)
(case (entity-type e)
((bullet) (any (lambda (en) (entities-overlap? e en)) enemies))
((enemy) (any (lambda (b) (entities-overlap? e b)) bullets))
(else #f)))
entities)))
(define (in-bounds? e)
(let ((y (entity-ref e #:y 0)))
(and (> y -20) (< y (+ +screen-height+ 20)))))
;; ── Update helpers ───────────────────────────────────────────────────────────
(define (player-vx input)
(cond ((input-held? input 'left) -4)
((input-held? input 'right) 4)
(else 0)))
(define (clamp-player-x player)
(entity-set player #:x
(max 0 (min (- +screen-width+ 16) (entity-ref player #:x 0)))))
(define (update-player player input scene)
(let ((updated (chain player
(entity-set _ #:vx (player-vx input))
(apply-velocity-x _)
(clamp-player-x _))))
(when (input-pressed? input 'a)
(play-sound 'shoot)
(scene-add-entity scene
(make-bullet (+ (entity-ref updated #:x 0) 6) 340)))
updated))
(define (move-projectile e)
(chain e
(entity-set _ #:x (+ (entity-ref e #:x 0) (entity-ref e #:vx 0)))
(entity-set _ #:y (+ (entity-ref e #:y 0) (entity-ref e #:vy 0)))))
(define (maybe-spawn-enemy! scene)
(when (zero? (modulo *frame-count* +spawn-interval+))
(scene-add-entity scene
(make-enemy (+ 20 (* (pseudo-random-integer 28) 20))))))
;; ── Render ───────────────────────────────────────────────────────────────────
(define (entity-color type)
(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))))
(define (draw-shmup-entity renderer e)
(let ((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) (entity-color (entity-type e)))
(sdl2:render-fill-rect! renderer (sdl2:make-rect x y w h))))
;; ── Game ─────────────────────────────────────────────────────────────────────
(define *game*
(make-game
title: "Demo: Shoot-em-up"
width: +screen-width+ height: +screen-height+
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)
(set! *frame-count* (+ *frame-count* 1))
(let* ((input (game-input game))
(scene (game-scene game))
(player (car (scene-entities scene)))
(player (update-player player input scene)))
(maybe-spawn-enemy! scene)
;; Replace player, then move all projectiles
(scene-entities-set! scene
(cons player (filter (lambda (e) (not (eq? (entity-type e) 'player)))
(scene-entities scene))))
(scene-update-entities scene
(lambda (e) (if (eq? (entity-type e) 'player) e (move-projectile e))))
;; Remove bullet/enemy collisions, then out-of-bounds
(let ((dead (find-dead (scene-entities scene))))
(scene-filter-entities scene (lambda (e) (not (memq e dead)))))
(scene-filter-entities scene
(lambda (e) (or (eq? (entity-type e) 'player) (in-bounds? e))))))
render: (lambda (game)
(for-each (lambda (e) (draw-shmup-entity (game-renderer game) e))
(scene-entities (game-scene game))))))
(game-run! *game*)
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