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;;; Chickadee Game Toolkit
;;; Copyright © 2017, 2021 David Thompson <dthompson2@worcester.edu>
;;;
;;; Licensed under the Apache License, Version 2.0 (the "License");
;;; you may not use this file except in compliance with the License.
;;; You may obtain a copy of the License at
;;;
;;; http://www.apache.org/licenses/LICENSE-2.0
;;;
;;; Unless required by applicable law or agreed to in writing, software
;;; distributed under the License is distributed on an "AS IS" BASIS,
;;; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
;;; See the License for the specific language governing permissions and
;;; limitations under the License.
;;; Commentary:
;;
;; Render to texture.
;;
;;; Code:
(define-module (chickadee graphics framebuffer)
#:use-module (ice-9 match)
#:use-module (srfi srfi-9)
#:use-module (system foreign)
#:use-module (gl)
#:use-module (gl enums)
#:use-module (chickadee math matrix)
#:use-module (chickadee graphics color)
#:use-module (chickadee graphics engine)
#:use-module (chickadee graphics gl)
#:use-module (chickadee graphics pixbuf)
#:use-module ((chickadee graphics texture) #:select (make-texture null-texture))
#:use-module (chickadee graphics viewport)
#:export (make-framebuffer
framebuffer?
framebuffer-texture
framebuffer-viewport
framebuffer-projection
null-framebuffer
g:framebuffer
current-framebuffer
with-framebuffer))
(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 projection)
framebuffer?
(id framebuffer-id)
(renderbuffer-id framebuffer-renderbuffer-id)
(texture framebuffer-texture)
(viewport framebuffer-viewport)
(projection framebuffer-projection))
(define null-framebuffer
(%make-framebuffer 0 0 null-texture null-viewport (make-identity-matrix4)))
(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 (apply-framebuffer framebuffer)
(gl-bind-framebuffer (version-3-0 framebuffer)
(framebuffer-id framebuffer)))
(define (bind-framebuffer framebuffer)
(gl-bind-framebuffer (version-3-0 framebuffer)
(framebuffer-id framebuffer)))
(define-graphics-finalizer framebuffer-finalizer
#:predicate framebuffer?
#:free free-framebuffer)
(define-graphics-state g:framebuffer
current-framebuffer
#:default null-framebuffer
#:bind bind-framebuffer)
(define %clear-color (transparency 0.0))
(define %draw-buffers (bytevector->pointer (u32vector (version-3-0 color-attachment0))))
(define* (make-framebuffer 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."
(assert-current-graphics-engine)
(let* ((framebuffer-id (generate-framebuffer))
(renderbuffer-id (generate-renderbuffer))
(texture (make-texture 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 and
;; projection matrix 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 #:clear-color %clear-color))
(projection (orthographic-projection 0 width height 0 0 1))
(framebuffer (%make-framebuffer framebuffer-id
renderbuffer-id
texture
viewport
projection)))
(graphics-engine-guard! framebuffer)
(with-graphics-state! ((g:framebuffer framebuffer))
;; Setup depth buffer.
(gl-bind-renderbuffer (version-3-0 renderbuffer)
renderbuffer-id)
(gl-renderbuffer-storage (version-3-0 renderbuffer)
(arb-framebuffer-object depth24-stencil8)
width
height)
(gl-bind-renderbuffer (version-3-0 renderbuffer) 0)
(gl-framebuffer-renderbuffer (version-3-0 framebuffer)
(arb-framebuffer-object depth-stencil-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 graphics texture) texture-id)
texture)
0)
(gl-draw-buffers 1 %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))
(define-syntax-rule (with-framebuffer framebuffer body ...)
;; As a convenience, initialize the viewport and projection matrix
;; as well so that the user doesn't have to explicitly make a
;; viewport and/or projection matrix unless they actually want to do
;; fancy viewport manipulations.
(with-graphics-state! ((g:framebuffer framebuffer)
(g:viewport (framebuffer-viewport framebuffer)))
(clear-viewport)
(with-projection (framebuffer-projection framebuffer)
body ...)))
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