1 /****************************************************************************
2 **
3 ** Copyright (C) 2016 The Qt Company Ltd.
4 ** Contact: https://www.qt.io/licensing/
5 **
6 ** This file is part of the documentation of the Qt Toolkit.
7 **
8 ** $QT_BEGIN_LICENSE:BSD$
9 ** Commercial License Usage
10 ** Licensees holding valid commercial Qt licenses may use this file in
11 ** accordance with the commercial license agreement provided with the
12 ** Software or, alternatively, in accordance with the terms contained in
13 ** a written agreement between you and The Qt Company. For licensing terms
14 ** and conditions see https://www.qt.io/terms-conditions. For further
15 ** information use the contact form at https://www.qt.io/contact-us.
16 **
17 ** BSD License Usage
18 ** Alternatively, you may use this file under the terms of the BSD license
19 ** as follows:
20 **
21 ** "Redistribution and use in source and binary forms, with or without
22 ** modification, are permitted provided that the following conditions are
23 ** met:
24 ** * Redistributions of source code must retain the above copyright
25 ** notice, this list of conditions and the following disclaimer.
26 ** * Redistributions in binary form must reproduce the above copyright
27 ** notice, this list of conditions and the following disclaimer in
28 ** the documentation and/or other materials provided with the
29 ** distribution.
30 ** * Neither the name of The Qt Company Ltd nor the names of its
31 ** contributors may be used to endorse or promote products derived
32 ** from this software without specific prior written permission.
33 **
34 **
35 ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
36 ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
37 ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
38 ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
39 ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
40 ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
41 ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
42 ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
43 ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
44 ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
45 ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
46 **
47 ** $QT_END_LICENSE$
48 **
49 ****************************************************************************/
50
51 //! [0]
52 class MyGLWidget : public QOpenGLWidget
53 {
54 public:
MyGLWidget(QWidget * parent)55 MyGLWidget(QWidget *parent) : QOpenGLWidget(parent) { }
56
57 protected:
initializeGL()58 void initializeGL() override
59 {
60 // Set up the rendering context, load shaders and other resources, etc.:
61 QOpenGLFunctions *f = QOpenGLContext::currentContext()->functions();
62 f->glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
63 ...
64 }
65
resizeGL(int w,int h)66 void resizeGL(int w, int h) override
67 {
68 // Update projection matrix and other size related settings:
69 m_projection.setToIdentity();
70 m_projection.perspective(45.0f, w / float(h), 0.01f, 100.0f);
71 ...
72 }
73
paintGL()74 void paintGL() override
75 {
76 // Draw the scene:
77 QOpenGLFunctions *f = QOpenGLContext::currentContext()->functions();
78 f->glClear(GL_COLOR_BUFFER_BIT);
79 ...
80 }
81
82 };
83 //! [0]
84
85 //! [1]
86 class MyGLWidget : public QOpenGLWidget, protected QOpenGLFunctions
87 {
88 ...
89 void initializeGL() override
90 {
91 initializeOpenGLFunctions();
92 glClearColor(...);
93 ...
94 }
95 ...
96 };
97 //! [1]
98
99 //! [2]
100 QOpenGLWidget *widget = new QOpenGLWidget(parent);
101 QSurfaceFormat format;
102 format.setDepthBufferSize(24);
103 format.setStencilBufferSize(8);
104 format.setVersion(3, 2);
105 format.setProfile(QSurfaceFormat::CoreProfile);
106 widget->setFormat(format); // must be called before the widget or its parent window gets shown
107 //! [2]
108
109 //! [3]
110 ...
111 void paintGL() override
112 {
113 QOpenGLFunctions_3_2_Core *f = QOpenGLContext::currentContext()->versionFunctions<QOpenGLFunctions_3_2_Core>();
114 ...
115 f->glDrawArraysInstanced(...);
116 ...
117 }
118 ...
119 //! [3]
120
121 //! [4]
122 class MyGLWidget : public QOpenGLWidget
123 {
124 ...
125
126 private:
127 QOpenGLVertexArrayObject m_vao;
128 QOpenGLBuffer m_vbo;
129 QOpenGLShaderProgram *m_program;
130 QOpenGLShader *m_shader;
131 QOpenGLTexture *m_texture;
132 };
133
MyGLWidget()134 MyGLWidget::MyGLWidget()
135 : m_program(0), m_shader(0), m_texture(0)
136 {
137 // No OpenGL resource initialization is done here.
138 }
139
~MyGLWidget()140 MyGLWidget::~MyGLWidget()
141 {
142 // Make sure the context is current and then explicitly
143 // destroy all underlying OpenGL resources.
144 makeCurrent();
145
146 delete m_texture;
147 delete m_shader;
148 delete m_program;
149
150 m_vbo.destroy();
151 m_vao.destroy();
152
153 doneCurrent();
154 }
155
initializeGL()156 void MyGLWidget::initializeGL()
157 {
158 m_vao.create();
159 if (m_vao.isCreated())
160 m_vao.bind();
161
162 m_vbo.create();
163 m_vbo.bind();
164 m_vbo.allocate(...);
165
166 m_texture = new QOpenGLTexture(QImage(...));
167
168 m_shader = new QOpenGLShader(...);
169 m_program = new QOpenGLShaderProgram(...);
170
171 ...
172 }
173 //! [4]
174
175 //! [5]
initializeGL()176 void MyGLWidget::initializeGL()
177 {
178 // context() and QOpenGLContext::currentContext() are equivalent when called from initializeGL or paintGL.
179 connect(context(), &QOpenGLContext::aboutToBeDestroyed, this, &MyGLWidget::cleanup);
180 }
181
cleanup()182 void MyGLWidget::cleanup()
183 {
184 makeCurrent();
185 delete m_texture;
186 m_texture = 0;
187 ...
188 doneCurrent();
189 }
190 //! [5]
191
192 //! [6]
main(int argc,char ** argv)193 int main(int argc, char **argv)
194 {
195 QApplication app(argc, argv);
196
197 QSurfaceFormat format;
198 format.setDepthBufferSize(24);
199 format.setStencilBufferSize(8);
200 format.setVersion(3, 2);
201 format.setProfile(QSurfaceFormat::CoreProfile);
202 QSurfaceFormat::setDefaultFormat(format);
203
204 MyWidget widget;
205 widget.show();
206
207 return app.exec();
208 }
209 //! [6]
210