scene.cpp Example File | Qt Widgets 5.6

Qt 5.6 | Qt Widgets | Boxes | scene.cpp Example File

Qt 5.6.2 Reference Documentation

# scene.cpp Example File

graphicsview/boxes/scene.cpp

      /****************************************************************************
      **
      ** Copyright (C) 2015 The Qt Company Ltd.
      ** Contact: http://www.qt.io/licensing/
      **
      ** This file is part of the demonstration applications of the Qt Toolkit.
      **
      ** $QT_BEGIN_LICENSE:LGPL21$
      ** Commercial License Usage
      ** Licensees holding valid commercial Qt licenses may use this file in
      ** accordance with the commercial license agreement provided with the
      ** Software or, alternatively, in accordance with the terms contained in
      ** a written agreement between you and The Qt Company. For licensing terms
      ** and conditions see http://www.qt.io/terms-conditions. For further
      ** information use the contact form at http://www.qt.io/contact-us.
      **
      ** 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 or version 3 as published by the Free
      ** Software Foundation and appearing in the file LICENSE.LGPLv21 and
      ** LICENSE.LGPLv3 included in the packaging of this file. Please review the
      ** following information to ensure the GNU Lesser General Public License
      ** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
      ** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
      **
      ** As a special exception, The Qt Company gives you certain additional
      ** rights. These rights are described in The Qt Company LGPL Exception
      ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
      **
      ** $QT_END_LICENSE$
      **
      ****************************************************************************/

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

      #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_DEAD_CODE_FROM_QT4_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)
      {
          // static to prevent glLoadMatrixf to fail on certain drivers
          static GLfloat mat[16];
          const float *data = m.constData();
          for (int index = 0; index < 16; ++index)
              mat[index] = data[index];
          glLoadMatrixf(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());
              glMultMatrixf(m.constData());

              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());
              glMultMatrixf(m.constData());

              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(std::cos(angle), std::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);
          qgluPerspective(60.0, width / height, 0.01, 15.0);

          glMatrixMode(GL_MODELVIEW);

          QMatrix4x4 view;
          view.rotate(m_trackBalls[2].rotation());
          view(2, 3) -= 2.0f * std::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;
          }
      }