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;; load the SDL module and some useful srfi's
(use-modules ((sdl sdl) #:prefix SDL:)
(figl gl)
(srfi srfi-1)
(srfi srfi-2)
(srfi srfi-9)
(ice-9 format)
(2d texture)
(2d sprite)
(2d game-loop)
(2d window)
(2d vector))
(set! *random-state* (random-state-from-platform))
;;;
;;; Particles
;;;
(define-record-type <particle>
(make-particle sprite position velocity)
particle?
(sprite particle-sprite)
(position particle-position set-particle-position!)
(velocity particle-velocity set-particle-velocity!))
(define (draw-particle particle)
(let* ((texture (sprite-texture (particle-sprite particle)))
(p (particle-position particle))
(x (vx p))
(y (vy p))
(x2 (+ x (texture-width texture)))
(y2 (+ y (texture-height texture))))
(gl-texture-coordinates 0 0)
(gl-vertex x y)
(gl-texture-coordinates 1 0)
(gl-vertex x2 y)
(gl-texture-coordinates 1 1)
(gl-vertex x2 y2)
(gl-texture-coordinates 0 1)
(gl-vertex x y2)))
(define (draw-particles particles)
(let ((texture (sprite-texture (particle-sprite (car particles)))))
(with-gl-bind-texture (texture-target texture-2d) (texture-id texture)
(gl-begin (begin-mode quads)
(gl-color 1 1 1)
(for-each (lambda (p) (draw-particle p)) particles)))))
(define (update-particle! particle)
(set-particle-position! particle
(v+ (particle-position particle)
(particle-velocity particle))))
;;;
;;; Demo
;;;
(define window-width 800)
(define window-height 600)
(open-window window-width window-height)
(define stars (load-sprite "stars.png" #:anchor #(0 0)))
(define particle-image (load-texture "bullet.png"))
(define num-particles 300)
(define particles
(list-tabulate num-particles
(lambda (n)
(make-particle (make-sprite particle-image)
(vector (random window-width)
(random window-height))
(vector (* (random:normal) 1)
(* (random:normal) 1))))))
(set-render-callback (lambda () (render)))
(set-update-callback (lambda () (update)))
(set-key-down-callback (lambda (key) (key-down key)))
(define (key-down key)
(case key
((SDLK_ESCAPE SDLK_q)
(close-window)
(quit))))
(define (render)
(draw-sprite stars)
(draw-particles particles))
(define (update)
(for-each update-particle! particles))
(run-game-loop)
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