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# scene.cpp Example File
demos/boxes/scene.cpp

     /****************************************************************************
     **
     ** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
     ** All rights reserved.
     ** Contact: Nokia Corporation (qt-info@nokia.com)
     **
     ** This file is part of the demonstration applications of the Qt Toolkit.
     **
     ** $QT_BEGIN_LICENSE:LGPL$
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     ** Licensees holding valid Qt Commercial licenses may use this file in
     ** accordance with the Qt Commercial License Agreement provided with the
     ** Software or, alternatively, in accordance with the terms contained in
     ** a written agreement between you and Nokia.
     **
     ** GNU Lesser General Public License Usage
     ** Alternatively, this file may be used under the terms of the GNU Lesser
     ** General Public License version 2.1 as published by the Free Software
     ** Foundation and appearing in the file LICENSE.LGPL included in the
     ** packaging of this file.  Please review the following information to
     ** ensure the GNU Lesser General Public License version 2.1 requirements
     ** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
     **
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     ** rights.  These rights are described in the Nokia Qt LGPL Exception
     ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
     **
     ** GNU General Public License Usage
     ** Alternatively, this file may be used under the terms of the GNU
     ** General Public License version 3.0 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 the GNU General Public License version 3.0 requirements will be
     ** met: http://www.gnu.org/copyleft/gpl.html.
     **
     ** If you have questions regarding the use of this file, please contact
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     ****************************************************************************/

     #include <QDebug>
     #include "scene.h"
     #include <QtGui/qmatrix4x4.h>
     #include <QtGui/qvector3d.h>

     #include "3rdparty/fbm.h"

     void checkGLErrors(const QString& prefix)
     {
         switch (glGetError()) {
         case GL_NO_ERROR:
             //qDebug() << prefix << tr("No error.");
             break;
         case GL_INVALID_ENUM:
             qDebug() << prefix << QObject::tr("Invalid enum.");
             break;
         case GL_INVALID_VALUE:
             qDebug() << prefix << QObject::tr("Invalid value.");
             break;
         case GL_INVALID_OPERATION:
             qDebug() << prefix << QObject::tr("Invalid operation.");
             break;
         case GL_STACK_OVERFLOW:
             qDebug() << prefix << QObject::tr("Stack overflow.");
             break;
         case GL_STACK_UNDERFLOW:
             qDebug() << prefix << QObject::tr("Stack underflow.");
             break;
         case GL_OUT_OF_MEMORY:
             qDebug() << prefix << QObject::tr("Out of memory.");
             break;
         default:
             qDebug() << prefix << QObject::tr("Unknown error.");
             break;
         }
     }

     //============================================================================//
     //                                  ColorEdit                                 //
     //============================================================================//

     ColorEdit::ColorEdit(QRgb initialColor, int id)
         : m_color(initialColor), m_id(id)
     {
         QHBoxLayout *layout = new QHBoxLayout;
         setLayout(layout);
         layout->setContentsMargins(0, 0, 0, 0);

         m_lineEdit = new QLineEdit(QString::number(m_color, 16));
         layout->addWidget(m_lineEdit);

         m_button = new QFrame;
         QPalette palette = m_button->palette();
         palette.setColor(QPalette::Window, QColor(m_color));
         m_button->setPalette(palette);
         m_button->setAutoFillBackground(true);
         m_button->setMinimumSize(32, 0);
         m_button->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Preferred);
         m_button->setFrameStyle(QFrame::StyledPanel | QFrame::Sunken);
         layout->addWidget(m_button);

         connect(m_lineEdit, SIGNAL(editingFinished()), this, SLOT(editDone()));
     }

     void ColorEdit::editDone()
     {
         bool ok;
         QRgb newColor = m_lineEdit->text().toUInt(&ok, 16);
         if (ok)
             setColor(newColor);
     }

     void ColorEdit::mousePressEvent(QMouseEvent *event)
     {
         if (event->button() == Qt::LeftButton) {
             QColor color(m_color);
             QColorDialog dialog(color, 0);
             dialog.setOption(QColorDialog::ShowAlphaChannel, true);
     // The ifdef block is a workaround for the beta, TODO: remove when bug 238525 is fixed
     #ifdef Q_WS_MAC
             dialog.setOption(QColorDialog::DontUseNativeDialog, true);
     #endif
             dialog.move(280, 120);
             if (dialog.exec() == QDialog::Rejected)
                 return;
             QRgb newColor = dialog.selectedColor().rgba();
             if (newColor == m_color)
                 return;
             setColor(newColor);
         }
     }

     void ColorEdit::setColor(QRgb color)
     {
         m_color = color;
         m_lineEdit->setText(QString::number(m_color, 16)); // "Clean up" text
         QPalette palette = m_button->palette();
         palette.setColor(QPalette::Window, QColor(m_color));
         m_button->setPalette(palette);
         emit colorChanged(m_color, m_id);
     }

     //============================================================================//
     //                                  FloatEdit                                 //
     //============================================================================//

     FloatEdit::FloatEdit(float initialValue, int id)
         : m_value(initialValue), m_id(id)
     {
         QHBoxLayout *layout = new QHBoxLayout;
         setLayout(layout);
         layout->setContentsMargins(0, 0, 0, 0);

         m_lineEdit = new QLineEdit(QString::number(m_value));
         layout->addWidget(m_lineEdit);

         connect(m_lineEdit, SIGNAL(editingFinished()), this, SLOT(editDone()));
     }

     void FloatEdit::editDone()
     {
         bool ok;
         float newValue = m_lineEdit->text().toFloat(&ok);
         if (ok) {
             m_value = newValue;
             m_lineEdit->setText(QString::number(m_value)); // "Clean up" text
             emit valueChanged(m_value, m_id);
         }
     }

     //============================================================================//
     //                           TwoSidedGraphicsWidget                           //
     //============================================================================//

     TwoSidedGraphicsWidget::TwoSidedGraphicsWidget(QGraphicsScene *scene)
         : QObject(scene)
         , m_current(0)
         , m_angle(0)
         , m_delta(0)
     {
         for (int i = 0; i < 2; ++i)
             m_proxyWidgets[i] = 0;
     }

     void TwoSidedGraphicsWidget::setWidget(int index, QWidget *widget)
     {
         if (index < 0 || index >= 2)
             {
                     qWarning("TwoSidedGraphicsWidget::setWidget: Index out of bounds, index == %d", index);
                     return;
             }

         GraphicsWidget *proxy = new GraphicsWidget;
         proxy->setWidget(widget);

         if (m_proxyWidgets[index])
             delete m_proxyWidgets[index];
         m_proxyWidgets[index] = proxy;

         proxy->setCacheMode(QGraphicsItem::ItemCoordinateCache);
         proxy->setZValue(1e30); // Make sure the dialog is drawn on top of all other (OpenGL) items

         if (index != m_current)
             proxy->setVisible(false);

         qobject_cast<QGraphicsScene *>(parent())->addItem(proxy);
     }

     QWidget *TwoSidedGraphicsWidget::widget(int index)
     {
         if (index < 0 || index >= 2)
             {
                     qWarning("TwoSidedGraphicsWidget::widget: Index out of bounds, index == %d", index);
                     return 0;
             }
         return m_proxyWidgets[index]->widget();
     }

     void TwoSidedGraphicsWidget::flip()
     {
         m_delta = (m_current == 0 ? 9 : -9);
         animateFlip();
     }

     void TwoSidedGraphicsWidget::animateFlip()
     {
         m_angle += m_delta;
         if (m_angle == 90) {
             int old = m_current;
             m_current ^= 1;
             m_proxyWidgets[old]->setVisible(false);
             m_proxyWidgets[m_current]->setVisible(true);
             m_proxyWidgets[m_current]->setGeometry(m_proxyWidgets[old]->geometry());
         }

         QRectF r = m_proxyWidgets[m_current]->boundingRect();
         m_proxyWidgets[m_current]->setTransform(QTransform()
             .translate(r.width() / 2, r.height() / 2)
             .rotate(m_angle - 180 * m_current, Qt::YAxis)
             .translate(-r.width() / 2, -r.height() / 2));

         if ((m_current == 0 && m_angle > 0) || (m_current == 1 && m_angle < 180))
             QTimer::singleShot(25, this, SLOT(animateFlip()));
     }

     QVariant GraphicsWidget::itemChange(GraphicsItemChange change, const QVariant &value)
     {
         if (change == ItemPositionChange && scene()) {
             QRectF rect = boundingRect();
             QPointF pos = value.toPointF();
             QRectF sceneRect = scene()->sceneRect();
             if (pos.x() + rect.left() < sceneRect.left())
                 pos.setX(sceneRect.left() - rect.left());
             else if (pos.x() + rect.right() >= sceneRect.right())
                 pos.setX(sceneRect.right() - rect.right());
             if (pos.y() + rect.top() < sceneRect.top())
                 pos.setY(sceneRect.top() - rect.top());
             else if (pos.y() + rect.bottom() >= sceneRect.bottom())
                 pos.setY(sceneRect.bottom() - rect.bottom());
             return pos;
         }
         return QGraphicsProxyWidget::itemChange(change, value);
     }

     void GraphicsWidget::resizeEvent(QGraphicsSceneResizeEvent *event)
     {
         setCacheMode(QGraphicsItem::NoCache);
         setCacheMode(QGraphicsItem::ItemCoordinateCache);
         QGraphicsProxyWidget::resizeEvent(event);
     }

     void GraphicsWidget::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
     {
         painter->setRenderHint(QPainter::Antialiasing, false);
         QGraphicsProxyWidget::paint(painter, option, widget);
         //painter->setRenderHint(QPainter::Antialiasing, true);
     }

     //============================================================================//
     //                             RenderOptionsDialog                            //
     //============================================================================//

     RenderOptionsDialog::RenderOptionsDialog()
         : QDialog(0, Qt::CustomizeWindowHint | Qt::WindowTitleHint)
     {
         setWindowOpacity(0.75);
         setWindowTitle(tr("Options (double click to flip)"));
         QGridLayout *layout = new QGridLayout;
         setLayout(layout);
         layout->setColumnStretch(1, 1);

         int row = 0;

         QCheckBox *check = new QCheckBox(tr("Dynamic cube map"));
         check->setCheckState(Qt::Unchecked);
         // Dynamic cube maps are only enabled when multi-texturing and render to texture are available.
         check->setEnabled(glActiveTexture && glGenFramebuffersEXT);
         connect(check, SIGNAL(stateChanged(int)), this, SIGNAL(dynamicCubemapToggled(int)));
         layout->addWidget(check, 0, 0, 1, 2);
         ++row;

         QPalette palette;

         // Load all .par files
         // .par files have a simple syntax for specifying user adjustable uniform variables.
         QSet<QByteArray> uniforms;
         QList<QString> filter = QStringList("*.par");
         QList<QFileInfo> files = QDir(":/res/boxes/").entryInfoList(filter, QDir::Files | QDir::Readable);

         foreach (QFileInfo fileInfo, files) {
             QFile file(fileInfo.absoluteFilePath());
             if (file.open(QIODevice::ReadOnly)) {
                 while (!file.atEnd()) {
                     QList<QByteArray> tokens = file.readLine().simplified().split(' ');
                     QList<QByteArray>::const_iterator it = tokens.begin();
                     if (it == tokens.end())
                         continue;
                     QByteArray type = *it;
                     if (++it == tokens.end())
                         continue;
                     QByteArray name = *it;
                     bool singleElement = (tokens.size() == 3); // type, name and one value
                     char counter[10] = "000000000";
                     int counterPos = 8; // position of last digit
                     while (++it != tokens.end()) {
                         m_parameterNames << name;
                         if (!singleElement) {
                             m_parameterNames.back() += "[";
                             m_parameterNames.back() += counter + counterPos;
                             m_parameterNames.back() += "]";
                             int j = 8; // position of last digit
                             ++counter[j];
                             while (j > 0 && counter[j] > '9') {
                                 counter[j] = '0';
                                 ++counter[--j];
                             }
                             if (j < counterPos)
                                 counterPos = j;
                         }

                         if (type == "color") {
                             layout->addWidget(new QLabel(m_parameterNames.back()));
                             bool ok;
                             ColorEdit *colorEdit = new ColorEdit(it->toUInt(&ok, 16), m_parameterNames.size() - 1);
                             m_parameterEdits << colorEdit;
                             layout->addWidget(colorEdit);
                             connect(colorEdit, SIGNAL(colorChanged(QRgb,int)), this, SLOT(setColorParameter(QRgb,int)));
                             ++row;
                         } else if (type == "float") {
                             layout->addWidget(new QLabel(m_parameterNames.back()));
                             bool ok;
                             FloatEdit *floatEdit = new FloatEdit(it->toFloat(&ok), m_parameterNames.size() - 1);
                             m_parameterEdits << floatEdit;
                             layout->addWidget(floatEdit);
                             connect(floatEdit, SIGNAL(valueChanged(float,int)), this, SLOT(setFloatParameter(float,int)));
                             ++row;
                         }
                     }
                 }
                 file.close();
             }
         }

         layout->addWidget(new QLabel(tr("Texture:")));
         m_textureCombo = new QComboBox;
         connect(m_textureCombo, SIGNAL(currentIndexChanged(int)), this, SIGNAL(textureChanged(int)));
         layout->addWidget(m_textureCombo);
         ++row;

         layout->addWidget(new QLabel(tr("Shader:")));
         m_shaderCombo = new QComboBox;
         connect(m_shaderCombo, SIGNAL(currentIndexChanged(int)), this, SIGNAL(shaderChanged(int)));
         layout->addWidget(m_shaderCombo);
         ++row;

         layout->setRowStretch(row, 1);
     }

     int RenderOptionsDialog::addTexture(const QString &name)
     {
         m_textureCombo->addItem(name);
         return m_textureCombo->count() - 1;
     }

     int RenderOptionsDialog::addShader(const QString &name)
     {
         m_shaderCombo->addItem(name);
         return m_shaderCombo->count() - 1;
     }

     void RenderOptionsDialog::emitParameterChanged()
     {
         foreach (ParameterEdit *edit, m_parameterEdits)
             edit->emitChange();
     }

     void RenderOptionsDialog::setColorParameter(QRgb color, int id)
     {
         emit colorParameterChanged(m_parameterNames[id], color);
     }

     void RenderOptionsDialog::setFloatParameter(float value, int id)
     {
         emit floatParameterChanged(m_parameterNames[id], value);
     }

     void RenderOptionsDialog::mouseDoubleClickEvent(QMouseEvent *event)
     {
         if (event->button() == Qt::LeftButton)
             emit doubleClicked();
     }

     //============================================================================//
     //                                 ItemDialog                                 //
     //============================================================================//

     ItemDialog::ItemDialog()
         : QDialog(0, Qt::CustomizeWindowHint | Qt::WindowTitleHint)
     {
         setWindowTitle(tr("Items (double click to flip)"));
         setWindowOpacity(0.75);
         resize(160, 100);

         QVBoxLayout *layout = new QVBoxLayout;
         setLayout(layout);
         QPushButton *button;

         button = new QPushButton(tr("Add Qt box"));
         layout->addWidget(button);
         connect(button, SIGNAL(clicked()), this, SLOT(triggerNewQtBox()));

         button = new QPushButton(tr("Add circle"));
         layout->addWidget(button);
         connect(button, SIGNAL(clicked()), this, SLOT(triggerNewCircleItem()));

         button = new QPushButton(tr("Add square"));
         layout->addWidget(button);
         connect(button, SIGNAL(clicked()), this, SLOT(triggerNewSquareItem()));

         layout->addStretch(1);
     }

     void ItemDialog::triggerNewQtBox()
     {
         emit newItemTriggered(QtBoxItem);
     }

     void ItemDialog::triggerNewCircleItem()
     {
         emit newItemTriggered(CircleItem);
     }

     void ItemDialog::triggerNewSquareItem()
     {
         emit newItemTriggered(SquareItem);
     }

     void ItemDialog::mouseDoubleClickEvent(QMouseEvent *event)
     {
         if (event->button() == Qt::LeftButton)
             emit doubleClicked();
     }

     //============================================================================//
     //                                    Scene                                   //
     //============================================================================//

     const static char environmentShaderText[] =
         "uniform samplerCube env;"
         "void main() {"
             "gl_FragColor = textureCube(env, gl_TexCoord[1].xyz);"
         "}";

     Scene::Scene(int width, int height, int maxTextureSize)
         : m_distExp(600)
         , m_frame(0)
         , m_maxTextureSize(maxTextureSize)
         , m_currentShader(0)
         , m_currentTexture(0)
         , m_dynamicCubemap(false)
         , m_updateAllCubemaps(true)
         , m_box(0)
         , m_vertexShader(0)
         , m_environmentShader(0)
         , m_environmentProgram(0)
     {
         setSceneRect(0, 0, width, height);

         m_trackBalls[0] = TrackBall(0.05f, QVector3D(0, 1, 0), TrackBall::Sphere);
         m_trackBalls[1] = TrackBall(0.005f, QVector3D(0, 0, 1), TrackBall::Sphere);
         m_trackBalls[2] = TrackBall(0.0f, QVector3D(0, 1, 0), TrackBall::Plane);

         m_renderOptions = new RenderOptionsDialog;
         m_renderOptions->move(20, 120);
         m_renderOptions->resize(m_renderOptions->sizeHint());

         connect(m_renderOptions, SIGNAL(dynamicCubemapToggled(int)), this, SLOT(toggleDynamicCubemap(int)));
         connect(m_renderOptions, SIGNAL(colorParameterChanged(QString,QRgb)), this, SLOT(setColorParameter(QString,QRgb)));
         connect(m_renderOptions, SIGNAL(floatParameterChanged(QString,float)), this, SLOT(setFloatParameter(QString,float)));
         connect(m_renderOptions, SIGNAL(textureChanged(int)), this, SLOT(setTexture(int)));
         connect(m_renderOptions, SIGNAL(shaderChanged(int)), this, SLOT(setShader(int)));

         m_itemDialog = new ItemDialog;
         connect(m_itemDialog, SIGNAL(newItemTriggered(ItemDialog::ItemType)), this, SLOT(newItem(ItemDialog::ItemType)));

         TwoSidedGraphicsWidget *twoSided = new TwoSidedGraphicsWidget(this);
         twoSided->setWidget(0, m_renderOptions);
         twoSided->setWidget(1, m_itemDialog);

         connect(m_renderOptions, SIGNAL(doubleClicked()), twoSided, SLOT(flip()));
         connect(m_itemDialog, SIGNAL(doubleClicked()), twoSided, SLOT(flip()));

         addItem(new QtBox(64, width - 64, height - 64));
         addItem(new QtBox(64, width - 64, 64));
         addItem(new QtBox(64, 64, height - 64));
         addItem(new QtBox(64, 64, 64));

         initGL();

         m_timer = new QTimer(this);
         m_timer->setInterval(20);
         connect(m_timer, SIGNAL(timeout()), this, SLOT(update()));
         m_timer->start();

         m_time.start();
     }

     Scene::~Scene()
     {
         if (m_box)
             delete m_box;
         foreach (GLTexture *texture, m_textures)
             if (texture) delete texture;
         if (m_mainCubemap)
             delete m_mainCubemap;
         foreach (QGLShaderProgram *program, m_programs)
             if (program) delete program;
         if (m_vertexShader)
             delete m_vertexShader;
         foreach (QGLShader *shader, m_fragmentShaders)
             if (shader) delete shader;
         foreach (GLRenderTargetCube *rt, m_cubemaps)
             if (rt) delete rt;
         if (m_environmentShader)
             delete m_environmentShader;
         if (m_environmentProgram)
             delete m_environmentProgram;
     }

     void Scene::initGL()
     {
         m_box = new GLRoundedBox(0.25f, 1.0f, 10);

         m_vertexShader = new QGLShader(QGLShader::Vertex);
         m_vertexShader->compileSourceFile(QLatin1String(":/res/boxes/basic.vsh"));

         QStringList list;
         list << ":/res/boxes/cubemap_posx.jpg" << ":/res/boxes/cubemap_negx.jpg" << ":/res/boxes/cubemap_posy.jpg"
              << ":/res/boxes/cubemap_negy.jpg" << ":/res/boxes/cubemap_posz.jpg" << ":/res/boxes/cubemap_negz.jpg";
         m_environment = new GLTextureCube(list, qMin(1024, m_maxTextureSize));
         m_environmentShader = new QGLShader(QGLShader::Fragment);
         m_environmentShader->compileSourceCode(environmentShaderText);
         m_environmentProgram = new QGLShaderProgram;
         m_environmentProgram->addShader(m_vertexShader);
         m_environmentProgram->addShader(m_environmentShader);
         m_environmentProgram->link();

         const int NOISE_SIZE = 128; // for a different size, B and BM in fbm.c must also be changed
         m_noise = new GLTexture3D(NOISE_SIZE, NOISE_SIZE, NOISE_SIZE);
         QRgb *data = new QRgb[NOISE_SIZE * NOISE_SIZE * NOISE_SIZE];
         memset(data, 0, NOISE_SIZE * NOISE_SIZE * NOISE_SIZE * sizeof(QRgb));
         QRgb *p = data;
         float pos[3];
         for (int k = 0; k < NOISE_SIZE; ++k) {
             pos[2] = k * (0x20 / (float)NOISE_SIZE);
             for (int j = 0; j < NOISE_SIZE; ++j) {
                 for (int i = 0; i < NOISE_SIZE; ++i) {
                     for (int byte = 0; byte < 4; ++byte) {
                         pos[0] = (i + (byte & 1) * 16) * (0x20 / (float)NOISE_SIZE);
                         pos[1] = (j + (byte & 2) * 8) * (0x20 / (float)NOISE_SIZE);
                         *p |= (int)(128.0f * (noise3(pos) + 1.0f)) << (byte * 8);
                     }
                     ++p;
                 }
             }
         }
         m_noise->load(NOISE_SIZE, NOISE_SIZE, NOISE_SIZE, data);
         delete[] data;

         m_mainCubemap = new GLRenderTargetCube(512);

         QStringList filter;
         QList<QFileInfo> files;

         // Load all .png files as textures
         m_currentTexture = 0;
         filter = QStringList("*.png");
         files = QDir(":/res/boxes/").entryInfoList(filter, QDir::Files | QDir::Readable);

         foreach (QFileInfo file, files) {
             GLTexture *texture = new GLTexture2D(file.absoluteFilePath(), qMin(256, m_maxTextureSize), qMin(256, m_maxTextureSize));
             if (texture->failed()) {
                 delete texture;
                 continue;
             }
             m_textures << texture;
             m_renderOptions->addTexture(file.baseName());
         }

         if (m_textures.size() == 0)
             m_textures << new GLTexture2D(qMin(64, m_maxTextureSize), qMin(64, m_maxTextureSize));

         // Load all .fsh files as fragment shaders
         m_currentShader = 0;
         filter = QStringList("*.fsh");
         files = QDir(":/res/boxes/").entryInfoList(filter, QDir::Files | QDir::Readable);
         foreach (QFileInfo file, files) {
             QGLShaderProgram *program = new QGLShaderProgram;
             QGLShader* shader = new QGLShader(QGLShader::Fragment);
             shader->compileSourceFile(file.absoluteFilePath());
             // The program does not take ownership over the shaders, so store them in a vector so they can be deleted afterwards.
             program->addShader(m_vertexShader);
             program->addShader(shader);
             if (!program->link()) {
                 qWarning("Failed to compile and link shader program");
                 qWarning("Vertex shader log:");
                 qWarning() << m_vertexShader->log();
                 qWarning() << "Fragment shader log ( file =" << file.absoluteFilePath() << "):";
                 qWarning() << shader->log();
                 qWarning("Shader program log:");
                 qWarning() << program->log();

                 delete shader;
                 delete program;
                 continue;
             }

             m_fragmentShaders << shader;
             m_programs << program;
             m_renderOptions->addShader(file.baseName());

             program->bind();
             m_cubemaps << ((program->uniformLocation("env") != -1) ? new GLRenderTargetCube(qMin(256, m_maxTextureSize)) : 0);
             program->release();
         }

         if (m_programs.size() == 0)
             m_programs << new QGLShaderProgram;

         m_renderOptions->emitParameterChanged();
     }

     static void loadMatrix(const QMatrix4x4& m)
     {
         GLfloat mat[16];
         const qreal *data = m.constData();
         for (int index = 0; index < 16; ++index)
             mat[index] = data[index];
         glLoadMatrixf(mat);
     }

     static void multMatrix(const QMatrix4x4& m)
     {
         GLfloat mat[16];
         const qreal *data = m.constData();
         for (int index = 0; index < 16; ++index)
             mat[index] = data[index];
         glMultMatrixf(mat);
     }

     // If one of the boxes should not be rendered, set excludeBox to its index.
     // If the main box should not be rendered, set excludeBox to -1.
     void Scene::renderBoxes(const QMatrix4x4 &view, int excludeBox)
     {
         QMatrix4x4 invView = view.inverted();

         // If multi-texturing is supported, use three saplers.
         if (glActiveTexture) {
             glActiveTexture(GL_TEXTURE0);
             m_textures[m_currentTexture]->bind();
             glActiveTexture(GL_TEXTURE2);
             m_noise->bind();
             glActiveTexture(GL_TEXTURE1);
         } else {
             m_textures[m_currentTexture]->bind();
         }

         glDisable(GL_LIGHTING);
         glDisable(GL_CULL_FACE);

         QMatrix4x4 viewRotation(view);
         viewRotation(3, 0) = viewRotation(3, 1) = viewRotation(3, 2) = 0.0f;
         viewRotation(0, 3) = viewRotation(1, 3) = viewRotation(2, 3) = 0.0f;
         viewRotation(3, 3) = 1.0f;
         loadMatrix(viewRotation);
         glScalef(20.0f, 20.0f, 20.0f);

         // Don't render the environment if the environment texture can't be set for the correct sampler.
         if (glActiveTexture) {
             m_environment->bind();
             m_environmentProgram->bind();
             m_environmentProgram->setUniformValue("tex", GLint(0));
             m_environmentProgram->setUniformValue("env", GLint(1));
             m_environmentProgram->setUniformValue("noise", GLint(2));
             m_box->draw();
             m_environmentProgram->release();
             m_environment->unbind();
         }

         loadMatrix(view);

         glEnable(GL_CULL_FACE);
         glEnable(GL_LIGHTING);

         for (int i = 0; i < m_programs.size(); ++i) {
             if (i == excludeBox)
                 continue;

             glPushMatrix();
             QMatrix4x4 m;
             m.rotate(m_trackBalls[1].rotation());
             multMatrix(m);

             glRotatef(360.0f * i / m_programs.size(), 0.0f, 0.0f, 1.0f);
             glTranslatef(2.0f, 0.0f, 0.0f);
             glScalef(0.3f, 0.6f, 0.6f);

             if (glActiveTexture) {
                 if (m_dynamicCubemap && m_cubemaps[i])
                     m_cubemaps[i]->bind();
                 else
                     m_environment->bind();
             }
             m_programs[i]->bind();
             m_programs[i]->setUniformValue("tex", GLint(0));
             m_programs[i]->setUniformValue("env", GLint(1));
             m_programs[i]->setUniformValue("noise", GLint(2));
             m_programs[i]->setUniformValue("view", view);
             m_programs[i]->setUniformValue("invView", invView);
             m_box->draw();
             m_programs[i]->release();

             if (glActiveTexture) {
                 if (m_dynamicCubemap && m_cubemaps[i])
                     m_cubemaps[i]->unbind();
                 else
                     m_environment->unbind();
             }
             glPopMatrix();
         }

         if (-1 != excludeBox) {
             QMatrix4x4 m;
             m.rotate(m_trackBalls[0].rotation());
             multMatrix(m);

             if (glActiveTexture) {
                 if (m_dynamicCubemap)
                     m_mainCubemap->bind();
                 else
                     m_environment->bind();
             }

             m_programs[m_currentShader]->bind();
             m_programs[m_currentShader]->setUniformValue("tex", GLint(0));
             m_programs[m_currentShader]->setUniformValue("env", GLint(1));
             m_programs[m_currentShader]->setUniformValue("noise", GLint(2));
             m_programs[m_currentShader]->setUniformValue("view", view);
             m_programs[m_currentShader]->setUniformValue("invView", invView);
             m_box->draw();
             m_programs[m_currentShader]->release();

             if (glActiveTexture) {
                 if (m_dynamicCubemap)
                     m_mainCubemap->unbind();
                 else
                     m_environment->unbind();
             }
         }

         if (glActiveTexture) {
             glActiveTexture(GL_TEXTURE2);
             m_noise->unbind();
             glActiveTexture(GL_TEXTURE0);
         }
         m_textures[m_currentTexture]->unbind();
     }

     void Scene::setStates()
     {
         //glClearColor(0.25f, 0.25f, 0.5f, 1.0f);

         glEnable(GL_DEPTH_TEST);
         glEnable(GL_CULL_FACE);
         glEnable(GL_LIGHTING);
         //glEnable(GL_COLOR_MATERIAL);
         glEnable(GL_TEXTURE_2D);
         glEnable(GL_NORMALIZE);

         glMatrixMode(GL_PROJECTION);
         glPushMatrix();
         glLoadIdentity();

         glMatrixMode(GL_MODELVIEW);
         glPushMatrix();
         glLoadIdentity();

         setLights();

         float materialSpecular[] = {0.5f, 0.5f, 0.5f, 1.0f};
         glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, materialSpecular);
         glMaterialf(GL_FRONT_AND_BACK, GL_SHININESS, 32.0f);
     }

     void Scene::setLights()
     {
         glColorMaterial(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE);
         //float lightColour[] = {1.0f, 1.0f, 1.0f, 1.0f};
         float lightDir[] = {0.0f, 0.0f, 1.0f, 0.0f};
         //glLightfv(GL_LIGHT0, GL_DIFFUSE, lightColour);
         //glLightfv(GL_LIGHT0, GL_SPECULAR, lightColour);
         glLightfv(GL_LIGHT0, GL_POSITION, lightDir);
         glLightModelf(GL_LIGHT_MODEL_LOCAL_VIEWER, 1.0f);
         glEnable(GL_LIGHT0);
     }

     void Scene::defaultStates()
     {
         //glClearColor(0.0f, 0.0f, 0.0f, 0.0f);

         glDisable(GL_DEPTH_TEST);
         glDisable(GL_CULL_FACE);
         glDisable(GL_LIGHTING);
         //glDisable(GL_COLOR_MATERIAL);
         glDisable(GL_TEXTURE_2D);
         glDisable(GL_LIGHT0);
         glDisable(GL_NORMALIZE);

         glMatrixMode(GL_MODELVIEW);
         glPopMatrix();

         glMatrixMode(GL_PROJECTION);
         glPopMatrix();

         glLightModelf(GL_LIGHT_MODEL_LOCAL_VIEWER, 0.0f);
         float defaultMaterialSpecular[] = {0.0f, 0.0f, 0.0f, 1.0f};
         glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, defaultMaterialSpecular);
         glMaterialf(GL_FRONT_AND_BACK, GL_SHININESS, 0.0f);
     }

     void Scene::renderCubemaps()
     {
         // To speed things up, only update the cubemaps for the small cubes every N frames.
         const int N = (m_updateAllCubemaps ? 1 : 3);

         QMatrix4x4 mat;
         GLRenderTargetCube::getProjectionMatrix(mat, 0.1f, 100.0f);

         glMatrixMode(GL_PROJECTION);
         glPushMatrix();
         loadMatrix(mat);

         glMatrixMode(GL_MODELVIEW);
         glPushMatrix();

         QVector3D center;

         for (int i = m_frame % N; i < m_cubemaps.size(); i += N) {
             if (0 == m_cubemaps[i])
                 continue;

             float angle = 2.0f * PI * i / m_cubemaps.size();

             center = m_trackBalls[1].rotation().rotatedVector(QVector3D(cos(angle), sin(angle), 0.0f));

             for (int face = 0; face < 6; ++face) {
                 m_cubemaps[i]->begin(face);

                 GLRenderTargetCube::getViewMatrix(mat, face);
                 QVector4D v = QVector4D(-center.x(), -center.y(), -center.z(), 1.0);
                 mat.setColumn(3, mat * v);

                 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
                 renderBoxes(mat, i);

                 m_cubemaps[i]->end();
             }
         }

         for (int face = 0; face < 6; ++face) {
             m_mainCubemap->begin(face);
             GLRenderTargetCube::getViewMatrix(mat, face);

             glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
             renderBoxes(mat, -1);

             m_mainCubemap->end();
         }

         glPopMatrix();

         glMatrixMode(GL_PROJECTION);
         glPopMatrix();

         m_updateAllCubemaps = false;
     }

     void Scene::drawBackground(QPainter *painter, const QRectF &)
     {
         float width = float(painter->device()->width());
         float height = float(painter->device()->height());

         painter->beginNativePainting();
         setStates();

         if (m_dynamicCubemap)
             renderCubemaps();

         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

         glMatrixMode(GL_PROJECTION);
         gluPerspective(60.0, width / height, 0.01, 15.0);

         glMatrixMode(GL_MODELVIEW);

         QMatrix4x4 view;
         view.rotate(m_trackBalls[2].rotation());
         view(2, 3) -= 2.0f * exp(m_distExp / 1200.0f);
         renderBoxes(view);

         defaultStates();
         ++m_frame;

         painter->endNativePainting();
     }

     QPointF Scene::pixelPosToViewPos(const QPointF& p)
     {
         return QPointF(2.0 * float(p.x()) / width() - 1.0,
                        1.0 - 2.0 * float(p.y()) / height());
     }

     void Scene::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
     {
         QGraphicsScene::mouseMoveEvent(event);
         if (event->isAccepted())
             return;

         if (event->buttons() & Qt::LeftButton) {
             m_trackBalls[0].move(pixelPosToViewPos(event->scenePos()), m_trackBalls[2].rotation().conjugate());
             event->accept();
         } else {
             m_trackBalls[0].release(pixelPosToViewPos(event->scenePos()), m_trackBalls[2].rotation().conjugate());
         }

         if (event->buttons() & Qt::RightButton) {
             m_trackBalls[1].move(pixelPosToViewPos(event->scenePos()), m_trackBalls[2].rotation().conjugate());
             event->accept();
         } else {
             m_trackBalls[1].release(pixelPosToViewPos(event->scenePos()), m_trackBalls[2].rotation().conjugate());
         }

         if (event->buttons() & Qt::MidButton) {
             m_trackBalls[2].move(pixelPosToViewPos(event->scenePos()), QQuaternion());
             event->accept();
         } else {
             m_trackBalls[2].release(pixelPosToViewPos(event->scenePos()), QQuaternion());
         }
     }

     void Scene::mousePressEvent(QGraphicsSceneMouseEvent *event)
     {
         QGraphicsScene::mousePressEvent(event);
         if (event->isAccepted())
             return;

         if (event->buttons() & Qt::LeftButton) {
             m_trackBalls[0].push(pixelPosToViewPos(event->scenePos()), m_trackBalls[2].rotation().conjugate());
             event->accept();
         }

         if (event->buttons() & Qt::RightButton) {
             m_trackBalls[1].push(pixelPosToViewPos(event->scenePos()), m_trackBalls[2].rotation().conjugate());
             event->accept();
         }

         if (event->buttons() & Qt::MidButton) {
             m_trackBalls[2].push(pixelPosToViewPos(event->scenePos()), QQuaternion());
             event->accept();
         }
     }

     void Scene::mouseReleaseEvent(QGraphicsSceneMouseEvent *event)
     {
         QGraphicsScene::mouseReleaseEvent(event);
         if (event->isAccepted())
             return;

         if (event->button() == Qt::LeftButton) {
             m_trackBalls[0].release(pixelPosToViewPos(event->scenePos()), m_trackBalls[2].rotation().conjugate());
             event->accept();
         }

         if (event->button() == Qt::RightButton) {
             m_trackBalls[1].release(pixelPosToViewPos(event->scenePos()), m_trackBalls[2].rotation().conjugate());
             event->accept();
         }

         if (event->button() == Qt::MidButton) {
             m_trackBalls[2].release(pixelPosToViewPos(event->scenePos()), QQuaternion());
             event->accept();
         }
     }

     void Scene::wheelEvent(QGraphicsSceneWheelEvent * event)
     {
         QGraphicsScene::wheelEvent(event);
         if (!event->isAccepted()) {
             m_distExp += event->delta();
             if (m_distExp < -8 * 120)
                 m_distExp = -8 * 120;
             if (m_distExp > 10 * 120)
                 m_distExp = 10 * 120;
             event->accept();
         }
     }

     void Scene::setShader(int index)
     {
         if (index >= 0 && index < m_fragmentShaders.size())
             m_currentShader = index;
     }

     void Scene::setTexture(int index)
     {
         if (index >= 0 && index < m_textures.size())
             m_currentTexture = index;
     }

     void Scene::toggleDynamicCubemap(int state)
     {
         if ((m_dynamicCubemap = (state == Qt::Checked)))
             m_updateAllCubemaps = true;
     }

     void Scene::setColorParameter(const QString &name, QRgb color)
     {
         // set the color in all programs
         foreach (QGLShaderProgram *program, m_programs) {
             program->bind();
             program->setUniformValue(program->uniformLocation(name), QColor(color));
             program->release();
         }
     }

     void Scene::setFloatParameter(const QString &name, float value)
     {
         // set the color in all programs
         foreach (QGLShaderProgram *program, m_programs) {
             program->bind();
             program->setUniformValue(program->uniformLocation(name), value);
             program->release();
         }
     }

     void Scene::newItem(ItemDialog::ItemType type)
     {
         QSize size = sceneRect().size().toSize();
         switch (type) {
         case ItemDialog::QtBoxItem:
             addItem(new QtBox(64, rand() % (size.width() - 64) + 32, rand() % (size.height() - 64) + 32));
             break;
         case ItemDialog::CircleItem:
             addItem(new CircleItem(64, rand() % (size.width() - 64) + 32, rand() % (size.height() - 64) + 32));
             break;
         case ItemDialog::SquareItem:
             addItem(new SquareItem(64, rand() % (size.width() - 64) + 32, rand() % (size.height() - 64) + 32));
             break;
         default:
             break;
         }
     }