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;;; Chickadee Game Toolkit
;;; Copyright © 2017 David Thompson <davet@gnu.org>
;;;
;;; Chickadee 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.
;;;
;;; Chickadee 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:
;;
;; Render to texture.
;;
;;; Code:
(define-module (chickadee render framebuffer)
#:use-module (oop goops)
#:use-module (ice-9 match)
#:use-module (srfi srfi-9)
#:use-module (system foreign)
#:use-module (gl)
#:use-module (gl enums)
#:use-module (chickadee render gl)
#:use-module (chickadee render gpu)
#:use-module ((chickadee render texture) #:select (make-texture null-texture))
#:use-module (chickadee render viewport)
#:export (make-framebuffer
framebuffer?
framebuffer-texture
framebuffer-viewport
null-framebuffer
apply-framebuffer
*framebuffer-state*))
(define (generate-framebuffer)
"Generate a new OpenGL framebuffer object."
(let ((bv (u32vector 1)))
(gl-gen-framebuffers 1 (bytevector->pointer bv))
(u32vector-ref bv 0)))
(define (generate-renderbuffer)
"Generate a new OpenGL renderbuffer object."
(let ((bv (u32vector 1)))
(gl-gen-renderbuffers 1 (bytevector->pointer bv))
(u32vector-ref bv 0)))
(define-record-type <framebuffer>
(%make-framebuffer id renderbuffer-id texture viewport)
framebuffer?
(id framebuffer-id)
(renderbuffer-id framebuffer-renderbuffer-id)
(texture framebuffer-texture)
(viewport framebuffer-viewport))
(define null-framebuffer
(%make-framebuffer 0 0 null-texture null-viewport))
(define <<framebuffer>> (class-of null-framebuffer))
(define (free-framebuffer framebuffer)
(gl-delete-renderbuffers 1
(bytevector->pointer
(u32vector
(framebuffer-renderbuffer-id framebuffer))))
(gl-delete-framebuffers 1
(bytevector->pointer
(u32vector
(framebuffer-id framebuffer)))))
(define-method (gpu-finalize (framebuffer <<framebuffer>>))
(free-framebuffer framebuffer))
(define (apply-framebuffer framebuffer)
(gl-bind-framebuffer (version-3-0 framebuffer)
(framebuffer-id framebuffer)))
(define *framebuffer-state*
(make-gpu-state apply-framebuffer null-framebuffer))
(define make-framebuffer
(let ((draw-buffers (u32vector (version-3-0 color-attachment0))))
(lambda* (width height #:key (min-filter 'linear) (mag-filter 'linear)
(wrap-s 'repeat) (wrap-t 'repeat))
"Create a new framebuffer that renders to a texture with
dimensions WIDTH x HEIGHT."
(let* ((framebuffer-id (generate-framebuffer))
(renderbuffer-id (generate-renderbuffer))
(texture (make-texture #f width height
#:min-filter min-filter
#:mag-filter mag-filter
#:wrap-s wrap-s
#:wrap-t wrap-t))
;; It is convenient to make a default viewport for the
;; framebuffer so that the rendering engine can set it
;; whenever it changes to this framebuffer, saving users
;; the trouble of having to this tedious task themselves.
(viewport (make-viewport 0 0 width height))
(framebuffer (%make-framebuffer framebuffer-id
renderbuffer-id
texture
viewport)))
(gpu-state-set! *framebuffer-state* framebuffer)
;; Setup depth buffer.
(gl-bind-renderbuffer (version-3-0 renderbuffer)
renderbuffer-id)
(gl-renderbuffer-storage (version-3-0 renderbuffer)
(pixel-format depth-component)
width
height)
(gl-framebuffer-renderbuffer (version-3-0 framebuffer)
(arb-framebuffer-object depth-attachment)
(version-3-0 renderbuffer)
renderbuffer-id)
;; Setup framebuffer.
(gl-framebuffer-texture-2d (version-3-0 framebuffer)
(version-3-0 color-attachment0)
(texture-target texture-2d)
((@@ (chickadee render texture) texture-id)
texture)
0)
(gl-draw-buffers 1 (bytevector->pointer draw-buffers))
;; Check for errors.
(unless (= (gl-check-framebuffer-status (version-3-0 framebuffer))
(version-3-0 framebuffer-complete))
(error "Framebuffer cannot be created"))
framebuffer))))
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