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# glwidget.cpp Example File
opengl/textures/glwidget.cpp

        /****************************************************************************
        **
        ** Copyright (C) 2005-2006 Trolltech AS. All rights reserved.
        **
        ** This file is part of the documentation of the Qt Toolkit.
        **
        ** This file may be used under the terms of the GNU General Public
        ** License version 2.0 as published by the Free Software Foundation
        ** and appearing in the file LICENSE.GPL included in the packaging of
        ** this file.  Please review the following information to ensure GNU
        ** General Public Licensing requirements will be met:
        ** http://www.trolltech.com/products/qt/opensource.html
        **
        ** If you are unsure which license is appropriate for your use, please
        ** review the following information:
        ** http://www.trolltech.com/products/qt/licensing.html or contact the
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        **
        ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
        ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
        **
        ****************************************************************************/

        #include <QtGui>
        #include <QtOpenGL>

        #include <math.h>

        #include "glwidget.h"

        GLuint GLWidget::sharedObject = 0;
        int GLWidget::refCount = 0;

        GLWidget::GLWidget(QWidget *parent, QGLWidget *shareWidget)
            : QGLWidget(parent, shareWidget)
        {
            clearColor = Qt::black;
            xRot = 0;
            yRot = 0;
            zRot = 0;
        }

        GLWidget::~GLWidget()
        {
            if (--refCount == 0) {
                makeCurrent();
                glDeleteLists(sharedObject, 1);
            }
        }

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

        QSize GLWidget::sizeHint() const
        {
            return QSize(200, 200);
        }

        void GLWidget::rotateBy(int xAngle, int yAngle, int zAngle)
        {
            xRot += xAngle;
            yRot += yAngle;
            zRot += zAngle;
            updateGL();
        }

        void GLWidget::setClearColor(const QColor &color)
        {
            clearColor = color;
            updateGL();
        }

        void GLWidget::initializeGL()
        {
            if (!sharedObject)
                sharedObject = makeObject();
            ++refCount;

            glEnable(GL_DEPTH_TEST);
            glEnable(GL_CULL_FACE);
            glEnable(GL_TEXTURE_2D);
        }

        void GLWidget::paintGL()
        {
            qglClearColor(clearColor);
            glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
            glLoadIdentity();
            glTranslated(0.0, 0.0, -10.0);
            glRotated(xRot / 16.0, 1.0, 0.0, 0.0);
            glRotated(yRot / 16.0, 0.0, 1.0, 0.0);
            glRotated(zRot / 16.0, 0.0, 0.0, 1.0);
            glCallList(sharedObject);
        }

        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();
            glOrtho(-0.5, +0.5, +0.5, -0.5, 4.0, 15.0);
            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) {
                rotateBy(8 * dy, 8 * dx, 0);
            } else if (event->buttons() & Qt::RightButton) {
                rotateBy(8 * dy, 0, 8 * dx);
            }
            lastPos = event->pos();
        }

        void GLWidget::mouseReleaseEvent(QMouseEvent * /* event */)
        {
            emit clicked();
        }

        GLuint GLWidget::makeObject()
        {
            static const int coords[6][4][3] = {
                { { +1, -1, -1 }, { -1, -1, -1 }, { -1, +1, -1 }, { +1, +1, -1 } },
                { { +1, +1, -1 }, { -1, +1, -1 }, { -1, +1, +1 }, { +1, +1, +1 } },
                { { +1, -1, +1 }, { +1, -1, -1 }, { +1, +1, -1 }, { +1, +1, +1 } },
                { { -1, -1, -1 }, { -1, -1, +1 }, { -1, +1, +1 }, { -1, +1, -1 } },
                { { +1, -1, +1 }, { -1, -1, +1 }, { -1, -1, -1 }, { +1, -1, -1 } },
                { { -1, -1, +1 }, { +1, -1, +1 }, { +1, +1, +1 }, { -1, +1, +1 } }
            };

            GLuint textures[6];
            for (int j=0; j < 6; ++j)
                textures[j] = bindTexture(QPixmap(QString(":/images/side%1.png").arg(j + 1)),
                                          GL_TEXTURE_2D);

            GLuint list = glGenLists(1);
            glNewList(list, GL_COMPILE);
            for (int i = 0; i < 6; ++i) {
                glBindTexture(GL_TEXTURE_2D, textures[i]);
                glBegin(GL_QUADS);
                for (int j = 0; j < 4; ++j) {
                    glTexCoord2d(j == 0 || j == 3, j == 0 || j == 1);
                    glVertex3d(0.2 * coords[i][j][0], 0.2 * coords[i][j][1],
                               0.2 * coords[i][j][2]);
                }
                glEnd();
            }

            glEndList();
            return list;
        }