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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 render 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 utils)
#:use-module (sly math)
#:use-module (sly mesh)
#:use-module (sly render shader)
#:use-module (sly signal)
#:use-module (sly render texture)
#:use-module (sly math 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)
#:positions (vector
(vector3 x1 y1 0)
(vector3 x2 y1 0)
(vector3 x2 y2 0)
(vector3 x1 y2 0))
#:textures (vector
(vector2 s1 t1)
(vector2 s2 t1)
(vector2 s2 t2)
(vector2 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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