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;;; Sly
;;; Copyright (C) 2013, 2014 David Thompson <dthompson2@worcester.edu>
;;;
;;; This program is free software: you can redistribute it and/or
;;; modify it under the terms of the GNU General Public License as
;;; published by the Free Software Foundation, either version 3 of the
;;; License, or (at your option) any later version.
;;;
;;; This program is distributed in the hope that it will be useful,
;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;;; General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with this program. If not, see
;;; <http://www.gnu.org/licenses/>.
;;; Commentary:
;;
;; Sprites are typically the most important part of a 2D game. This
;; module provides sprites as an abstraction around OpenGL textures.
;;
;;; Code:
(define-module (sly sprite)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-26)
#:use-module (gl)
#:use-module (gl contrib packed-struct)
#:use-module ((sdl sdl) #:prefix SDL:)
#:use-module (sly color)
#:use-module (sly config)
#:use-module (sly agenda)
#:use-module (sly helpers)
#:use-module (sly math)
#:use-module (sly mesh)
#:use-module (sly shader)
#:use-module (sly signal)
#:use-module (sly texture)
#:use-module (sly vector)
#:export (make-sprite
load-sprite
make-animated-sprite))
;;;
;;; Sprites
;;;
(define* (make-sprite texture #:optional #:key
(shader (load-default-shader))
(anchor 'center)
(color white))
"Return a 2D rectangular mesh that displays the image TEXTURE. The
size of the mesh is the size of TEXTURE, in pixels. Optionally, a
custom SHADER can be specified."
(let* ((anchor (anchor-texture texture anchor))
(x1 (- (vx anchor)))
(y1 (- (vy anchor)))
(x2 (+ x1 (texture-width texture)))
(y2 (+ y1 (texture-height texture)))
(s1 (texture-s1 texture))
(t1 (texture-t1 texture))
(s2 (texture-s2 texture))
(t2 (texture-t2 texture)))
(make-mesh
#:shader shader
#:texture texture
#:indices #(0 3 2 0 2 1)
#:data `(("position" ,(vector
(vector x1 y1 0)
(vector x2 y1 0)
(vector x2 y2 0)
(vector x1 y2 0)))
("tex" ,(vector
(vector s1 t1)
(vector s2 t1)
(vector s2 t2)
(vector s1 t2)))))))
(define* (load-sprite file-name #:optional #:key (shader (load-default-shader))
(anchor 'center) (color white))
"Return a sprite mesh for the texture loaded from FILE-NAME.
Optionally, a custom SHADER can be specified."
(make-sprite (load-texture file-name) #:shader shader
#:anchor anchor #:color color))
(define* (make-animated-sprite textures frame-duration #:optional #:key
(loop? #t)
(shader (load-default-shader)))
"Return a signal that iterates through the list TEXTURES and
displays them each for FRAME-DURATION ticks. The optional LOOP? flag
specifies if the animation should play once or indefinitely.
Optionally, a SHADER can be specified, otherwise the default mesh
shader is used."
(let ((frames (map (cut make-sprite <> #:shader shader) textures)))
(signal-generator
(define (animate)
(for-each (lambda (frame)
(yield frame)
(wait frame-duration))
frames))
(if loop?
(forever (animate))
(animate)))))
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