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comparison Framework/OpenGL/WebAssemblyOpenGLContext.cpp @ 616:97926984d5d0

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WebAssembly sample using Scene2D
author Sebastien Jodogne <s.jodogne@gmail.com>
date Thu, 02 May 2019 13:27:41 +0200
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children 7efa2543699d
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615:b4de8272e8fb 616:97926984d5d0
1 /**
2 * Stone of Orthanc
3 * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
4 * Department, University Hospital of Liege, Belgium
5 * Copyright (C) 2017-2019 Osimis S.A., Belgium
6 *
7 * This program is free software: you can redistribute it and/or
8 * modify it under the terms of the GNU Affero General Public License
9 * as published by the Free Software Foundation, either version 3 of
10 * the License, or (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful, but
13 * WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Affero General Public License for more details.
16 *
17 * You should have received a copy of the GNU Affero General Public License
18 * along with this program. If not, see <http://www.gnu.org/licenses/>.
19 **/
20
21
22 #include "WebAssemblyOpenGLContext.h"
23
24 #if ORTHANC_ENABLE_WASM == 1
25
26 #include <Core/OrthancException.h>
27
28 #include <emscripten/html5.h>
29 #include <boost/math/special_functions/round.hpp>
30
31 namespace OrthancStone
32 {
33 namespace OpenGL
34 {
35 class WebAssemblyOpenGLContext::PImpl
36 {
37 private:
38 std::string canvas_;
39 EMSCRIPTEN_WEBGL_CONTEXT_HANDLE context_;
40 unsigned int canvasWidth_;
41 unsigned int canvasHeight_;
42
43 public:
44 PImpl(const std::string& canvas) :
45 canvas_(canvas)
46 {
47 // Context configuration
48 EmscriptenWebGLContextAttributes attr;
49 emscripten_webgl_init_context_attributes(&attr);
50
51 context_ = emscripten_webgl_create_context(canvas.c_str(), &attr);
52 if (context_ < 0)
53 {
54 throw Orthanc::OrthancException(Orthanc::ErrorCode_InternalError,
55 "Cannot create an OpenGL context for canvas: " + canvas);
56 }
57
58 UpdateSize();
59 }
60
61 ~PImpl()
62 {
63 emscripten_webgl_destroy_context(context_);
64 }
65
66 void MakeCurrent()
67 {
68 if (emscripten_webgl_make_context_current(context_) != EMSCRIPTEN_RESULT_SUCCESS)
69 {
70 throw Orthanc::OrthancException(Orthanc::ErrorCode_InternalError,
71 "Cannot set the OpenGL context");
72 }
73 }
74
75 void SwapBuffer()
76 {
77 /**
78 * "Rendered WebGL content is implicitly presented (displayed to
79 * the user) on the canvas when the event handler that renders with
80 * WebGL returns back to the browser event loop."
81 * https://emscripten.org/docs/api_reference/html5.h.html#webgl-context
82 *
83 * Could call "emscripten_webgl_commit_frame()" if
84 * "explicitSwapControl" option were set to "true".
85 **/
86 }
87
88 unsigned int GetCanvasWidth() const
89 {
90 return canvasWidth_;
91 }
92
93 unsigned int GetCanvasHeight() const
94 {
95 return canvasHeight_;
96 }
97
98 void UpdateSize()
99 {
100 double w, h;
101 emscripten_get_element_css_size(canvas_.c_str(), &w, &h);
102
103 /**
104 * Emscripten has the function emscripten_get_element_css_size()
105 * to query the width and height of a named HTML element. I'm
106 * calling this first to get the initial size of the canvas DOM
107 * element, and then call emscripten_set_canvas_size() to
108 * initialize the framebuffer size of the canvas to the same
109 * size as its DOM element.
110 * https://floooh.github.io/2017/02/22/emsc-html.html
111 **/
112
113 if (w <= 0 ||
114 h <= 0)
115 {
116 canvasWidth_ = 0;
117 canvasHeight_ = 0;
118 }
119 else
120 {
121 canvasWidth_ = static_cast<unsigned int>(boost::math::iround(w));
122 canvasHeight_ = static_cast<unsigned int>(boost::math::iround(h));
123 }
124
125 emscripten_set_canvas_element_size(canvas_.c_str(), canvasWidth_, canvasHeight_);
126 }
127 };
128
129
130 WebAssemblyOpenGLContext::WebAssemblyOpenGLContext(const std::string& canvas) :
131 pimpl_(new PImpl(canvas))
132 {
133 }
134
135 void WebAssemblyOpenGLContext::MakeCurrent()
136 {
137 assert(pimpl_.get() != NULL);
138 pimpl_->MakeCurrent();
139 }
140
141
142 void WebAssemblyOpenGLContext::SwapBuffer()
143 {
144 assert(pimpl_.get() != NULL);
145 pimpl_->SwapBuffer();
146 }
147
148 unsigned int WebAssemblyOpenGLContext::GetCanvasWidth() const
149 {
150 assert(pimpl_.get() != NULL);
151 return pimpl_->GetCanvasWidth();
152 }
153
154 unsigned int WebAssemblyOpenGLContext::GetCanvasHeight() const
155 {
156 assert(pimpl_.get() != NULL);
157 return pimpl_->GetCanvasHeight();
158 }
159
160 void WebAssemblyOpenGLContext::UpdateSize()
161 {
162 assert(pimpl_.get() != NULL);
163 pimpl_->UpdateSize();
164 }
165 }
166 }
167
168 #endif