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;;; guile-2d
;;; Copyright (C) 2013 David Thompson <dthompson2@worcester.edu>
;;;
;;; Guile-2d is free software: you can redistribute it and/or modify it
;;; under the terms of the GNU Lesser General Public License as
;;; published by the Free Software Foundation, either version 3 of the
;;; License, or (at your option) any later version.
;;;
;;; Guile-2d 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
;;; Lesser General Public License for more details.
;;;
;;; You should have received a copy of the GNU Lesser General Public
;;; License along with this program. If not, see
;;; <http://www.gnu.org/licenses/>.
;;; Commentary:
;;
;; Animations represent a sequence of textures and/or texture regions.
;;
;;; Code:
(define-module (2d animation)
#:use-module (srfi srfi-9)
#:use-module (2d texture))
;;;
;;; Animations
;;;
;; The <animation> type represents a vector of textures or texture
;; regions that are to be played in sequence and possibly looped.
(define-record-type <animation>
(make-animation frames frame-duration loop)
animation?
(frames animation-frames)
(frame-duration animation-frame-duration)
(loop animation-loop?))
(define (animation-frame animation index)
"Return the texture for the given frame INDEX."
(vector-ref (animation-frames animation) index))
(define (animation-length animation)
"Return the number of frames in the ANIMATION."
(vector-length (animation-frames animation)))
(define (animation-duration animation)
"Return the total duration of ANIMATION in ticks."
(* (animation-length animation)
(animation-frame-duration animation)))
(export make-animation
animation?
animation-frames
animation-frame-duration
animation-loop?
animation-frame
animation-length
animation-duration)
;; The <animator> type encapsulates the state for playing an
;; animation.
(define-record-type <animator>
(%make-animator animation frame time playing)
animator?
(animation animator-animation)
(frame animator-frame set-animator-frame!)
(time animator-time set-animator-time!)
(playing animator-playing? set-animator-playing!))
(define (make-animator animation)
"Creates a new animation animator object."
(%make-animator animation 0 0 #t))
(define (animator-frame-complete? animator)
(>= (animator-time animator)
(animation-frame-duration (animator-animation animator))))
(define (animator-next-frame animator)
"Return the next frame index for the animation ANIMATOR. Return -1 when
the animation is complete."
(modulo (1+ (animator-frame animator))
(animation-length (animator-animation animator))))
(define (animator-texture animator)
"Returns the texture for the animation at the current frame index."
(animation-frame (animator-animation animator)
(animator-frame animator)))
(define (animator-next! animator)
"Advance to the next animation frame for the given animation ANIMATOR."
(let ((next-frame (animator-next-frame animator))
(animation (animator-animation animator)))
(set-animator-time! animator 0)
(set-animator-frame! animator next-frame)
(set-animator-playing! animator (or (not (zero? next-frame))
(animation-loop? animation)))))
(define (animator-update! animator)
"Increments the frame time for the animation ANIMATOR and advances to
the next frame in the animation if necessary."
(when (animator-playing? animator)
(set-animator-time! animator (1+ (animator-time animator)))
(when (animator-frame-complete? animator)
(animator-next! animator))))
(export make-animator
animator?
animator-animation
animator-frame
animator-time
animator-frame-complete?
animator-playing?
animator-next-frame
animator-texture
animator-next!
animator-update!)
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