summaryrefslogtreecommitdiff
path: root/sly/render/context.scm
blob: fb28eda050637bd333dc4ad47accd2c9c54c1827 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
;;; 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:
;;
;; Manages OpenGL state and reduces state changes.
;;
;;; Code:

(define-module (sly render context)
  #:use-module (ice-9 q)
  #:use-module (srfi srfi-9)
  #:use-module (srfi srfi-42)
  #:use-module (gl)
  #:use-module (gl enums)
  #:use-module (gl low-level)
  #:use-module (sly wrappers gl)
  #:use-module (sly math transform)
  #:use-module (sly render shader)
  #:use-module (sly render texture)
  #:use-module (sly render utils)
  #:use-module (sly render mesh)
  #:export (make-render-context
            render-context?
            with-render-context with-temp-transform
            render-context-blend-mode set-render-context-blend-mode!
            render-context-depth-test? set-render-context-depth-test?!
            render-context-texture set-render-context-texture!
            render-context-shader set-render-context-shader!
            render-context-mesh set-render-context-mesh!))

(define-record-type <render-context>
  (%make-render-context blend-mode depth-test? texture shader
                        mesh transform-stack)
  render-context?
  (blend-mode render-context-blend-mode %set-render-context-blend-mode!)
  (depth-test? render-context-depth-test? %set-render-context-depth-test?!)
  (texture render-context-texture %set-render-context-texture!)
  (shader render-context-shader %set-render-context-shader!)
  (mesh render-context-mesh %set-render-context-mesh!)
  (transform-stack render-context-transform-stack))

(define (make-null-transform)
  (make-transform 0 0 0 0
                  0 0 0 0
                  0 0 0 0
                  0 0 0 0))

(define (make-transform-stack size)
  (let ((stack (make-q)))
    (do-ec (: i 128) (q-push! stack (make-null-transform)))
    stack))

(define* (make-render-context #:optional (transform-stack-size 32))
  (%make-render-context #f #f #f #f #f
                        (make-transform-stack transform-stack-size)))

(define (render-context-reset! context)
  (gl-disable (enable-cap blend))
  (%set-render-context-blend-mode! context #f)
  (gl-disable (enable-cap depth-test))
  (%set-render-context-depth-test?! context #f)
  (glBindTexture (texture-target texture-2d) 0)
  (%set-render-context-texture! context #f)
  (glUseProgram 0)
  (%set-render-context-shader! context #f)
  (glBindVertexArray 0)
  (%set-render-context-mesh! context #f))

(define-syntax-rule (with-render-context context body ...)
  (begin (render-context-reset! context) body ...))

(define (set-render-context-blend-mode! context blend-mode)
  (unless (equal? (render-context-blend-mode context) blend-mode)
    (if blend-mode
        (begin
          (gl-enable (enable-cap blend))
          (apply-blend-mode blend-mode))
        ;; Turn off blending if there is no blend-mode specified.
        (gl-disable (enable-cap blend)))
    (%set-render-context-blend-mode! context blend-mode)))

(define (set-render-context-depth-test?! context depth-test?)
  (unless (eq? (render-context-depth-test? context) depth-test?)
    (if depth-test?
        (gl-enable (enable-cap depth-test))
        (gl-disable (enable-cap depth-test)))
    (%set-render-context-depth-test?! context depth-test?)))

(define (set-render-context-texture! context texture)
  (let ((current-texture (render-context-texture context)))
    (unless (equal? current-texture texture)
      (if texture
          (begin
            ;; Enable texturing if it was disabled.
            (unless current-texture
              (gl-enable (enable-cap texture-2d)))
            (apply-texture texture))
          (gl-disable (enable-cap texture-2d)))
      (%set-render-context-texture! context texture))))

(define (set-render-context-shader! context shader)
  (unless (equal? (render-context-shader context) shader)
    (apply-shader-program shader)
    (%set-render-context-shader! context shader)))

(define (set-render-context-mesh! context mesh)
  (unless (equal? (render-context-mesh context) mesh)
    (apply-mesh mesh)
    (%set-render-context-mesh! context mesh)))

;; emacs: (put 'with-temp-transform 'scheme-indent-function 2)
(define-syntax-rule (with-temp-transform context name body ...)
  (let* ((stack (render-context-transform-stack context))
         (name (q-pop! stack)))
    (begin body ...)
    (q-push! stack name)))