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;;; Sly
;;; Copyright (C) 2014 David Thompson <davet@gnu.org>
;;;
;;; Sly 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.
;;;
;;; Sly 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:
;;
;; Scene graph
;;
;;; Code:
(define-module (sly scene)
#:use-module (srfi srfi-9)
#:use-module (srfi srfi-26)
#:use-module (sly mesh)
#:use-module (sly quaternion)
#:use-module (sly signal)
#:use-module (sly transform)
#:use-module (sly transition)
#:export (scene-node
make-scene-node
scene-root
scene-node?
scene-node-position scene-node-scale scene-node-rotation
scene-node-uniforms scene-node-children
update-scene-node draw-scene-node))
(define-record-type <scene-node>
(%make-scene-node position scale rotation uniforms children)
scene-node?
(position scene-node-position)
(scale scene-node-scale)
(rotation scene-node-rotation)
(prev-position scene-node-prev-position set-scene-node-prev-position!)
(prev-scale scene-node-prev-scale set-scene-node-prev-scale!)
(prev-rotation scene-node-prev-rotation set-scene-node-prev-rotation!)
(transform scene-node-transform set-scene-node-transform!)
(uniforms scene-node-uniforms)
(children scene-node-children))
(define* (make-scene-node #:optional #:key
(position #(0 0))
(scale 1)
(rotation identity-quaternion)
(uniforms '())
(children '())
#:allow-other-keys)
(let ((node (%make-scene-node position scale rotation uniforms children)))
(update-scene-node node)
(recompute-transform! node 0)
node))
(define-syntax-rule (scene-node (field val) ...)
(apply make-scene-node
(append (list (symbol->keyword 'field) val) ...)))
(define (scene-node-dirty? node)
(define (different? a b)
(not (equal? (a node) (b node))))
(or (different? scene-node-position scene-node-prev-position)
(different? scene-node-scale scene-node-prev-scale)
(different? scene-node-rotation scene-node-prev-rotation)))
(define (scene-root . children)
(make-scene-node #:children children))
(define (update-scene-node node)
(signal-let ((node node))
(when (scene-node? node)
(signal-let ((position (scene-node-position node))
(scale (scene-node-scale node))
(rotation (scene-node-rotation node))
(children (scene-node-children node)))
(set-scene-node-prev-position! node position)
(set-scene-node-prev-scale! node scale)
(set-scene-node-prev-rotation! node rotation)
(for-each update-scene-node children)))))
(define (interpolate current prev alpha)
(if (or (not prev)
(equal? current prev))
current
(vector-interpolate prev current alpha)))
(define (recompute-transform! node alpha)
(signal-let ((position (scene-node-position node))
(%scale (scene-node-scale node))
(rotation (scene-node-rotation node)))
(let ((t (transform*
(translate
(interpolate position
(scene-node-prev-position node)
alpha))
(quaternion->transform
(quaternion-slerp rotation
(scene-node-prev-rotation node)
alpha))
(scale (interpolate %scale
(scene-node-prev-scale node)
alpha)))))
(set-scene-node-transform! node t)
t)))
(define* (draw-scene-node node alpha transform #:optional (uniforms '()))
(signal-let ((node node))
(if (mesh? node)
(draw-mesh node `(("mvp" ,transform)
,@uniforms))
(let ((transform
(transform* transform
(if (scene-node-dirty? node)
(recompute-transform! node alpha)
(scene-node-transform node)))))
(signal-let ((children (scene-node-children node)))
(for-each (cut draw-scene-node <> alpha transform
(scene-node-uniforms node))
children))))))
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