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# glwidget.cpp Example File

opengl/hellogl/glwidget.cpp

     /****************************************************************************
     **
     ** Copyright (C) 2015 The Qt Company Ltd.
     ** Contact: http://www.qt.io/licensing/
     **
     ** This file is part of the examples 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 The Qt Company Ltd nor the names of its
     **     contributors may be used to endorse or promote products derived
     **     from this software without specific prior written permission.
     **
     **
     ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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     ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
     **
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     ****************************************************************************/

     #include <QtGui>
     #include <QtOpenGL>

     #include <math.h>

     #include "glwidget.h"
     #include "qtlogo.h"

     #ifndef GL_MULTISAMPLE
     #define GL_MULTISAMPLE  0x809D
     #endif

     GLWidget::GLWidget(QWidget *parent)
         : QGLWidget(QGLFormat(QGL::SampleBuffers), parent)
     {
         logo = 0;
         xRot = 0;
         yRot = 0;
         zRot = 0;

         qtGreen = QColor::fromCmykF(0.40, 0.0, 1.0, 0.0);
         qtPurple = QColor::fromCmykF(0.39, 0.39, 0.0, 0.0);
     }

     GLWidget::~GLWidget()
     {
     }

     QSize GLWidget::minimumSizeHint() const
     {
         return QSize(50, 50);
     }

     QSize GLWidget::sizeHint() const
     {
         return QSize(400, 400);
     }

     static void qNormalizeAngle(int &angle)
     {
         while (angle < 0)
             angle += 360 * 16;
         while (angle > 360 * 16)
             angle -= 360 * 16;
     }

     void GLWidget::setXRotation(int angle)
     {
         qNormalizeAngle(angle);
         if (angle != xRot) {
             xRot = angle;
             emit xRotationChanged(angle);
             updateGL();
         }
     }

     void GLWidget::setYRotation(int angle)
     {
         qNormalizeAngle(angle);
         if (angle != yRot) {
             yRot = angle;
             emit yRotationChanged(angle);
             updateGL();
         }
     }

     void GLWidget::setZRotation(int angle)
     {
         qNormalizeAngle(angle);
         if (angle != zRot) {
             zRot = angle;
             emit zRotationChanged(angle);
             updateGL();
         }
     }

     void GLWidget::initializeGL()
     {
         qglClearColor(qtPurple.dark());

         logo = new QtLogo(this, 64);
         logo->setColor(qtGreen.dark());

         glEnable(GL_DEPTH_TEST);
         glEnable(GL_CULL_FACE);
         glShadeModel(GL_SMOOTH);
         glEnable(GL_LIGHTING);
         glEnable(GL_LIGHT0);
         glEnable(GL_MULTISAMPLE);
         static GLfloat lightPosition[4] = { 0.5, 5.0, 7.0, 1.0 };
         glLightfv(GL_LIGHT0, GL_POSITION, lightPosition);
     }

     void GLWidget::paintGL()
     {
         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
         glLoadIdentity();
         glTranslatef(0.0, 0.0, -10.0);
         glRotatef(xRot / 16.0, 1.0, 0.0, 0.0);
         glRotatef(yRot / 16.0, 0.0, 1.0, 0.0);
         glRotatef(zRot / 16.0, 0.0, 0.0, 1.0);
         logo->draw();
     }

     void GLWidget::resizeGL(int width, int height)
     {
         int side = qMin(width, height);
         glViewport((width - side) / 2, (height - side) / 2, side, side);

         glMatrixMode(GL_PROJECTION);
         glLoadIdentity();
     #ifdef QT_OPENGL_ES_1
         glOrthof(-0.5, +0.5, -0.5, +0.5, 4.0, 15.0);
     #else
         glOrtho(-0.5, +0.5, -0.5, +0.5, 4.0, 15.0);
     #endif
         glMatrixMode(GL_MODELVIEW);
     }

     void GLWidget::mousePressEvent(QMouseEvent *event)
     {
         lastPos = event->pos();
     }

     void GLWidget::mouseMoveEvent(QMouseEvent *event)
     {
         int dx = event->x() - lastPos.x();
         int dy = event->y() - lastPos.y();

         if (event->buttons() & Qt::LeftButton) {
             setXRotation(xRot + 8 * dy);
             setYRotation(yRot + 8 * dx);
         } else if (event->buttons() & Qt::RightButton) {
             setXRotation(xRot + 8 * dy);
             setZRotation(zRot + 8 * dx);
         }
         lastPos = event->pos();
     }