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** This file is part of the examples of the Qt Toolkit.
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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;
}
