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

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 ** General Public License version 3.0 as published by the Free Software
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 #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;
 }