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<title>Qt 4.8: mainwidget.cpp Example File (opengl/cube/mainwidget.cpp)</title>
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<h1 class="title">mainwidget.cpp Example File</h1>
<span class="small-subtitle">opengl/cube/mainwidget.cpp</span>
<!-- $$$opengl/cube/mainwidget.cpp-description -->
<div class="descr"> <a name="details"></a>
<pre class="cpp"> <span class="comment">/****************************************************************************
**
** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** You may use this file under the terms of the BSD license as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
** * Redistributions of source code must retain the above copyright
** notice, this list of conditions and the following disclaimer.
** * Redistributions in binary form must reproduce the above copyright
** notice, this list of conditions and the following disclaimer in
** the documentation and/or other materials provided with the
** distribution.
** * Neither the name of Nokia Corporation and its Subsidiary(-ies) nor
** the names of its contributors may be used to endorse or promote
** products derived from this software without specific prior written
** permission.
**
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** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
** $QT_END_LICENSE$
**
****************************************************************************/</span>
<span class="preprocessor">#include "mainwidget.h"</span>
<span class="preprocessor">#include "geometryengine.h"</span>
<span class="preprocessor">#include <QtOpenGL/QGLShaderProgram></span>
<span class="preprocessor">#include <QBasicTimer></span>
<span class="preprocessor">#include <QMouseEvent></span>
<span class="preprocessor">#include <QDebug></span>
<span class="preprocessor">#include <math.h></span>
<span class="preprocessor">#include <locale.h></span>
MainWidget<span class="operator">::</span>MainWidget(<span class="type"><a href="qwidget.html">QWidget</a></span> <span class="operator">*</span>parent) :
<span class="type"><a href="qglwidget.html">QGLWidget</a></span>(parent)<span class="operator">,</span>
timer(<span class="keyword">new</span> <span class="type"><a href="qbasictimer.html">QBasicTimer</a></span>)<span class="operator">,</span>
program(<span class="keyword">new</span> <span class="type"><a href="qglshaderprogram.html">QGLShaderProgram</a></span>)<span class="operator">,</span>
geometries(<span class="keyword">new</span> GeometryEngine)
{
}
MainWidget<span class="operator">::</span><span class="operator">~</span>MainWidget()
{
<span class="keyword">delete</span> timer; timer <span class="operator">=</span> <span class="number">0</span>;
<span class="keyword">delete</span> program; program <span class="operator">=</span> <span class="number">0</span>;
<span class="keyword">delete</span> geometries; geometries <span class="operator">=</span> <span class="number">0</span>;
deleteTexture(texture);
}
<span class="type">void</span> MainWidget<span class="operator">::</span>mousePressEvent(<span class="type"><a href="qmouseevent.html">QMouseEvent</a></span> <span class="operator">*</span>e)
{
<span class="comment">// Saving mouse press position</span>
mousePressPosition <span class="operator">=</span> QVector2D(e<span class="operator">-</span><span class="operator">></span>posF());
}
<span class="type">void</span> MainWidget<span class="operator">::</span>mouseReleaseEvent(<span class="type"><a href="qmouseevent.html">QMouseEvent</a></span> <span class="operator">*</span>e)
{
<span class="comment">// Mouse release position - mouse press position</span>
QVector2D diff <span class="operator">=</span> QVector2D(e<span class="operator">-</span><span class="operator">></span>posF()) <span class="operator">-</span> mousePressPosition;
<span class="comment">// Rotation axis is perpendicular to the mouse position difference</span>
<span class="comment">// vector</span>
QVector3D n <span class="operator">=</span> QVector3D(diff<span class="operator">.</span>y()<span class="operator">,</span> diff<span class="operator">.</span>x()<span class="operator">,</span> <span class="number">0.0</span>)<span class="operator">.</span>normalized();
<span class="comment">// Accelerate angular speed relative to the length of the mouse sweep</span>
<span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span> acc <span class="operator">=</span> diff<span class="operator">.</span>length() <span class="operator">/</span> <span class="number">100.0</span>;
<span class="comment">// Calculate new rotation axis as weighted sum</span>
rotationAxis <span class="operator">=</span> (rotationAxis <span class="operator">*</span> angularSpeed <span class="operator">+</span> n <span class="operator">*</span> acc)<span class="operator">.</span>normalized();
<span class="comment">// Increase angular speed</span>
angularSpeed <span class="operator">+</span><span class="operator">=</span> acc;
}
<span class="type">void</span> MainWidget<span class="operator">::</span>timerEvent(<span class="type"><a href="qtimerevent.html">QTimerEvent</a></span> <span class="operator">*</span>e)
{
Q_UNUSED(e);
<span class="comment">// Decrease angular speed (friction)</span>
angularSpeed <span class="operator">*</span><span class="operator">=</span> <span class="number">0.99</span>;
<span class="comment">// Stop rotation when speed goes below threshold</span>
<span class="keyword">if</span> (angularSpeed <span class="operator"><</span> <span class="number">0.01</span>)
angularSpeed <span class="operator">=</span> <span class="number">0.0</span>;
<span class="keyword">else</span> {
<span class="comment">// Update rotation</span>
rotation <span class="operator">=</span> <span class="type"><a href="qquaternion.html">QQuaternion</a></span><span class="operator">::</span>fromAxisAndAngle(rotationAxis<span class="operator">,</span> angularSpeed) <span class="operator">*</span> rotation;
<span class="comment">// Update scene</span>
updateGL();
}
}
<span class="type">void</span> MainWidget<span class="operator">::</span>initializeGL()
{
initializeGLFunctions();
qglClearColor(<span class="type"><a href="qt.html">Qt</a></span><span class="operator">::</span>black);
<a href="qtglobal.html#qDebug">qDebug</a>() <span class="operator"><</span><span class="operator"><</span> <span class="string">"Initializing shaders..."</span>;
initShaders();
<a href="qtglobal.html#qDebug">qDebug</a>() <span class="operator"><</span><span class="operator"><</span> <span class="string">"Initializing textures..."</span>;
initTextures();
<span class="comment">// Enable depth buffer</span>
glEnable(GL_DEPTH_TEST);
<span class="comment">// Enable back face culling</span>
glEnable(GL_CULL_FACE);
<a href="qtglobal.html#qDebug">qDebug</a>() <span class="operator"><</span><span class="operator"><</span> <span class="string">"Initializing geometries..."</span>;
geometries<span class="operator">-</span><span class="operator">></span>init();
<span class="comment">// using QBasicTimer because its faster that QTimer</span>
timer<span class="operator">-</span><span class="operator">></span>start(<span class="number">12</span><span class="operator">,</span> <span class="keyword">this</span>);
}
<span class="type">void</span> MainWidget<span class="operator">::</span>initShaders()
{
<span class="comment">// Overriding system locale until shaders are compiled</span>
setlocale(LC_NUMERIC<span class="operator">,</span> <span class="string">"C"</span>);
<span class="comment">// Compiling vertex shader</span>
<span class="keyword">if</span> (<span class="operator">!</span>program<span class="operator">-</span><span class="operator">></span>addShaderFromSourceFile(<span class="type"><a href="qglshader.html">QGLShader</a></span><span class="operator">::</span>Vertex<span class="operator">,</span> <span class="string">":/vshader.glsl"</span>))
close();
<span class="comment">// Compiling fragment shader</span>
<span class="keyword">if</span> (<span class="operator">!</span>program<span class="operator">-</span><span class="operator">></span>addShaderFromSourceFile(<span class="type"><a href="qglshader.html">QGLShader</a></span><span class="operator">::</span>Fragment<span class="operator">,</span> <span class="string">":/fshader.glsl"</span>))
close();
<span class="comment">// Linking shader pipeline</span>
<span class="keyword">if</span> (<span class="operator">!</span>program<span class="operator">-</span><span class="operator">></span>link())
close();
<span class="comment">// Binding shader pipeline for use</span>
<span class="keyword">if</span> (<span class="operator">!</span>program<span class="operator">-</span><span class="operator">></span>bind())
close();
<span class="comment">// Restore system locale</span>
setlocale(LC_ALL<span class="operator">,</span> <span class="string">""</span>);
}
<span class="type">void</span> MainWidget<span class="operator">::</span>initTextures()
{
<span class="comment">// Loading cube.png to texture unit 0</span>
glActiveTexture(GL_TEXTURE0);
glEnable(GL_TEXTURE_2D);
texture <span class="operator">=</span> bindTexture(<span class="type"><a href="qimage.html">QImage</a></span>(<span class="string">":/cube.png"</span>));
<span class="comment">// Set nearest filtering mode for texture minification</span>
glTexParameterf(GL_TEXTURE_2D<span class="operator">,</span> GL_TEXTURE_MIN_FILTER<span class="operator">,</span> GL_NEAREST);
<span class="comment">// Set bilinear filtering mode for texture magnification</span>
glTexParameterf(GL_TEXTURE_2D<span class="operator">,</span> GL_TEXTURE_MAG_FILTER<span class="operator">,</span> GL_LINEAR);
<span class="comment">// Wrap texture coordinates by repeating</span>
<span class="comment">// f.ex. texture coordinate (1.1, 1.2) is same as (0.1, 0.2)</span>
glTexParameterf(GL_TEXTURE_2D<span class="operator">,</span> GL_TEXTURE_WRAP_S<span class="operator">,</span> GL_REPEAT);
glTexParameterf(GL_TEXTURE_2D<span class="operator">,</span> GL_TEXTURE_WRAP_T<span class="operator">,</span> GL_REPEAT);
}
<span class="type">void</span> MainWidget<span class="operator">::</span>resizeGL(<span class="type">int</span> w<span class="operator">,</span> <span class="type">int</span> h)
{
<span class="comment">// Set OpenGL viewport to cover whole widget</span>
glViewport(<span class="number">0</span><span class="operator">,</span> <span class="number">0</span><span class="operator">,</span> w<span class="operator">,</span> h);
<span class="comment">// Calculate aspect ratio</span>
<span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span> aspect <span class="operator">=</span> (<span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span>)w <span class="operator">/</span> ((<span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span>)h<span class="operator">?</span>h:<span class="number">1</span>);
<span class="comment">// Set near plane to 3.0, far plane to 7.0, field of view 45 degrees</span>
<span class="keyword">const</span> <span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span> zNear <span class="operator">=</span> <span class="number">3.0</span><span class="operator">,</span> zFar <span class="operator">=</span> <span class="number">7.0</span><span class="operator">,</span> fov <span class="operator">=</span> <span class="number">45.0</span>;
<span class="comment">// Reset projection</span>
projection<span class="operator">.</span>setToIdentity();
<span class="comment">// Set perspective projection</span>
projection<span class="operator">.</span>perspective(fov<span class="operator">,</span> aspect<span class="operator">,</span> zNear<span class="operator">,</span> zFar);
}
<span class="type">void</span> MainWidget<span class="operator">::</span>paintGL()
{
<span class="comment">// Clear color and depth buffer</span>
glClear(GL_COLOR_BUFFER_BIT <span class="operator">|</span> GL_DEPTH_BUFFER_BIT);
<span class="comment">// Calculate model view transformation</span>
QMatrix4x4 matrix;
matrix<span class="operator">.</span>translate(<span class="number">0.0</span><span class="operator">,</span> <span class="number">0.0</span><span class="operator">,</span> <span class="operator">-</span><span class="number">5.0</span>);
matrix<span class="operator">.</span>rotate(rotation);
<span class="comment">// Set modelview-projection matrix</span>
program<span class="operator">-</span><span class="operator">></span>setUniformValue(<span class="string">"mvp_matrix"</span><span class="operator">,</span> projection <span class="operator">*</span> matrix);
<span class="comment">// Using texture unit 0 which contains cube.png</span>
program<span class="operator">-</span><span class="operator">></span>setUniformValue(<span class="string">"texture"</span><span class="operator">,</span> <span class="number">0</span>);
<span class="comment">// Draw cube geometry</span>
geometries<span class="operator">-</span><span class="operator">></span>drawCubeGeometry(program);
}</pre>
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<!-- @@@opengl/cube/mainwidget.cpp -->
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