- Change extent to trapezoid shape

- Visualize the viewed area using QgsRubberBand
-  Address reviews

python/3d/auto_generated/qgs3dmapsettings.sip.in

@@ -27,13 +27,6 @@ Definition of the world.
 #include "qgs3dmapsettings.h"
 %End
   public:
-    enum ViewSyncMode
-    {
-      NoSync,
-      Sync3DTo2D,
-      Sync2DTo3D
-    };
-
     Qgs3DMapSettings();
 %Docstring
 Constructor for Qgs3DMapSettings
@@ -628,17 +621,31 @@ Sets the renderer usage
 .. versionadded:: 3.24
 %End
 
-    ViewSyncMode viewSyncMode() const;
+    Qgis::ViewSyncMode viewSyncMode() const;
 %Docstring
 Returns the view sync mode (used to syncronize the 2D main map canvas and the 3D camera navigation)
 
 .. versionadded:: 3.26
 %End
 
-    void setViewSyncMode( ViewSyncMode mode );
+    void setViewSyncMode( Qgis::ViewSyncMode mode );
 %Docstring
 Sets the view sync mode (used to syncronize the 2D main map canvas and the 3D camera navigation)
 
+.. versionadded:: 3.26
+%End
+
+    bool viewFrustumVisualizationEnabled() const;
+%Docstring
+Returns whether the camera's view frustum is visualized on the 2D map canvas
+
+.. versionadded:: 3.26
+%End
+
+    void setViewFrustumVisualizationEnabled( bool enabled );
+%Docstring
+Sets whether the camera's view frustum is visualized on the 2D map canvas
+
 .. versionadded:: 3.26
 %End
 
@@ -849,6 +856,13 @@ Emitted when shadow rendering settings are changed
 Emitted when the FPS counter is enabled or disabled
 
 .. versionadded:: 3.18
+%End
+
+    void viewFrustumVisualizationEnabledChanged();
+%Docstring
+Emitted when the camera's view frustum visualization on the main 2D map canvas is enabled or disabled
+
+.. versionadded:: 3.26
 %End
 
   private:

python/core/auto_additions/qgis.py

@@ -1303,6 +1303,14 @@ Qgis.RendererUsage.__doc__ = 'Usage of the renderer.\n\n.. versionadded:: 3.24\n
 # --
 Qgis.RendererUsage.baseClass = Qgis
 # monkey patching scoped based enum
+Qgis.ViewSyncMode.NoSync.__doc__ = ""
+Qgis.ViewSyncMode.Sync3DTo2D.__doc__ = ""
+Qgis.ViewSyncMode.Sync2DTo3D.__doc__ = ""
+Qgis.ViewSyncMode.BothWaysSync.__doc__ = ""
+Qgis.ViewSyncMode.__doc__ = '\n\n' + '* ``NoSync``: ' + Qgis.ViewSyncMode.NoSync.__doc__ + '\n' + '* ``Sync3DTo2D``: ' + Qgis.ViewSyncMode.Sync3DTo2D.__doc__ + '\n' + '* ``Sync2DTo3D``: ' + Qgis.ViewSyncMode.Sync2DTo3D.__doc__ + '\n' + '* ``BothWaysSync``: ' + Qgis.ViewSyncMode.BothWaysSync.__doc__
+# --
+Qgis.ViewSyncMode.baseClass = Qgis
+# monkey patching scoped based enum
 Qgis.HistoryProviderBackend.LocalProfile.__doc__ = "Local profile"
 Qgis.HistoryProviderBackend.__doc__ = 'History provider backends.\n\n.. versionadded:: 3.24\n\n' + '* ``LocalProfile``: ' + Qgis.HistoryProviderBackend.LocalProfile.__doc__
 # --

python/core/auto_generated/qgis.sip.in

@@ -835,6 +835,14 @@ The development version
       Unknown,
     };
 
+    enum class ViewSyncMode
+    {
+      NoSync,
+      Sync3DTo2D,
+      Sync2DTo3D,
+      BothWaysSync
+    };
+
     enum class HistoryProviderBackend
     {
       LocalProfile,

src/3d/qgs3dmapscene.cpp

@@ -146,6 +146,7 @@ Qgs3DMapScene::Qgs3DMapScene( const Qgs3DMapSettings &map, QgsAbstract3DEngine *
   connect( &map, &Qgs3DMapSettings::fpsCounterEnabledChanged, this, &Qgs3DMapScene::fpsCounterEnabledChanged );
   connect( &map, &Qgs3DMapSettings::cameraMovementSpeedChanged, this, &Qgs3DMapScene::onCameraMovementSpeedChanged );
 
+
   connect( QgsApplication::sourceCache(), &QgsSourceCache::remoteSourceFetched, this, [ = ]( const QString & url )
   {
     const QList<QgsMapLayer *> modelVectorLayers = mModelVectorLayers;
@@ -247,32 +248,56 @@ void Qgs3DMapScene::viewZoomFull()
   mCameraController->resetView( 1.5 * std::sqrt( a * a - side * side ) );  // assuming FOV being 45 degrees
 }
 
-void Qgs3DMapScene::viewExtent( const QgsRectangle &extent )
+void Qgs3DMapScene::setViewFrom2DExtent( const QgsRectangle &extent )
 {
   QgsPointXY center = extent.center();
-  QgsVector3D centerWrld = mMap.mapToWorldCoordinates( QVector3D( center.x(), center.y(), 0 ) );
+  QgsVector3D centerWorld = mMap.mapToWorldCoordinates( QVector3D( center.x(), center.y(), 0 ) );
   QgsVector3D p1 = mMap.mapToWorldCoordinates( QVector3D( extent.xMinimum(), extent.yMinimum(), 0 ) );
   QgsVector3D p2 = mMap.mapToWorldCoordinates( QVector3D( extent.xMaximum(), extent.yMaximum(), 0 ) );
 
-  float side = std::max( std::abs( p1.x() - p2.x() ), std::abs( p1.z() - p2.z() ) );
+  float xSide = std::abs( p1.x() - p2.x() );
-  float a =  side / 2.0f / std::sin( qDegreesToRadians( cameraController()->camera()->fieldOfView() ) / 2.0f );
+  float ySide = std::abs( p1.z() - p2.z() );
-  mCameraController->setViewFromTop( centerWrld.x(), centerWrld.z(), std::sqrt( a * a - side * side ) );
+  if ( xSide < ySide )
+  {
+    float fov = 2 * std::atan( std::tan( qDegreesToRadians( cameraController()->camera()->fieldOfView() ) / 2 ) * cameraController()->camera()->aspectRatio() );
+    float r = xSide / 2.0f / std::tan( fov / 2.0f );
+    mCameraController->setViewFromTop( centerWorld.x(), centerWorld.z(), r );
+  }
+  else
+  {
+    float fov = qDegreesToRadians( cameraController()->camera()->fieldOfView() );
+    float r = ySide / 2.0f / std::tan( fov / 2.0f );
+    mCameraController->setViewFromTop( centerWorld.x(), centerWorld.z(), r );
+  }
 }
 
-QgsRectangle Qgs3DMapScene::viewFrustum2DExtent()
+QVector<QgsPointXY> Qgs3DMapScene::viewFrustum2DExtent()
 {
-  QVector4D p = mCameraController->camera()->projectionMatrix() * mCameraController->camera()->viewMatrix() * mCameraController->camera()->viewCenter();
+  Qt3DRender::QCamera *camera = mCameraController->camera();
-  double maxDepth = p.z();// p.w();
   const QRect viewport = mCameraController->viewport();
-  QgsRectangle extent;
+  QVector<QgsPointXY> extent;
-  extent.setMinimal();
+  QVector<int> pointsOrder = { 0, 1, 3, 2 };
-  for ( int i = 0; i < 8; ++i )
+  for ( int i : pointsOrder )
   {
     const QPoint p( ( ( i >> 0 ) & 1 ) ? 0 : viewport.width(), ( ( i >> 1 ) & 1 ) ? 0 : viewport.height() );
-    const double depth = ( ( i >> 2 ) & 1 ) ? 0 : maxDepth;
+    QgsRay3D ray = Qgs3DUtils::rayFromScreenPoint( p, viewport.size(), camera );
-    QVector3D pWorld = Qgs3DUtils::screenPointToWorldPos( p, depth, viewport.size(), mCameraController->camera() );
+    QVector3D dir = ray.direction();
-    QgsVector3D pMap = mMap.worldToMapCoordinates( pWorld );
+    if ( dir.y() == 0.0 )
-    extent.include( QgsPointXY( pMap.x(), pMap.y() ) );
+      dir.setY( 0.0001 );
+    double t = - ray.origin().y() / dir.y();
+    if ( t < 0 )
+    {
+      // If the projected point is on the back of the camera we choose the farthest point in the front
+      t = camera->farPlane();
+    }
+    else
+    {
+      // If the projected point is on the front of the camera we choose the closest between it and farthest point in the front
+      t = std::min<float>( t, camera->farPlane() );
+    }
+    QVector3D planePoint = ray.origin() + t * dir;
+    QgsVector3D pMap = mMap.worldToMapCoordinates( planePoint );
+    extent.push_back( QgsPointXY( pMap.x(), pMap.y() ) );
   }
   return extent;
 }
@@ -385,7 +410,7 @@ void Qgs3DMapScene::onCameraChanged()
 
   onShadowSettingsChanged();
 
-  QgsRectangle extent2D = viewFrustum2DExtent();
+  QVector<QgsPointXY> extent2D = viewFrustum2DExtent();
   emit viewed2DExtentFrom3DChanged( extent2D );
 }
 

src/3d/qgs3dmapscene.h

@@ -86,14 +86,14 @@ class _3D_EXPORT Qgs3DMapScene : public Qt3DCore::QEntity
      *
      * \since QGIS 3.26
      */
-    void viewExtent( const QgsRectangle &extent );
+    void setViewFrom2DExtent( const QgsRectangle &extent );
 
     /**
-     * Calculates the 2D extent viewed by the 3D camera
+     * Calculates the 2D extent viewed by the 3D camera as the vertices of the viewed trapezoid
      *
      * \since QGIS 3.26
      */
-    QgsRectangle viewFrustum2DExtent();
+    QVector<QgsPointXY> viewFrustum2DExtent();
 
     //! Returns number of pending jobs of the terrain entity
     int terrainPendingJobsCount() const;
@@ -165,7 +165,7 @@ class _3D_EXPORT Qgs3DMapScene : public Qt3DCore::QEntity
      *
      * \since QGIS 3.26
      */
-    void viewed2DExtentFrom3DChanged( QgsRectangle extent );
+    void viewed2DExtentFrom3DChanged( QVector<QgsPointXY> extent );
 
   public slots:
     //! Updates the temporale entities

src/3d/qgs3dmapsettings.cpp

@@ -84,6 +84,7 @@ Qgs3DMapSettings::Qgs3DMapSettings( const Qgs3DMapSettings &other )
   , mEyeDomeLightingStrength( other.mEyeDomeLightingStrength )
   , mEyeDomeLightingDistance( other.mEyeDomeLightingDistance )
   , mViewSyncMode( other.mViewSyncMode )
+  , mVisualizeViewFrustum( other.mVisualizeViewFrustum )
   , mDebugShadowMapEnabled( other.mDebugShadowMapEnabled )
   , mDebugShadowMapCorner( other.mDebugShadowMapCorner )
   , mDebugShadowMapSize( other.mDebugShadowMapSize )
@@ -273,7 +274,8 @@ void Qgs3DMapSettings::readXml( const QDomElement &elem, const QgsReadWriteConte
   mEyeDomeLightingDistance = elemEyeDomeLighting.attribute( "eye-dome-lighting-distance", QStringLiteral( "1" ) ).toInt();
 
   QDomElement elemNavigationSync = elem.firstChildElement( QStringLiteral( "navigation-sync" ) );
-  mViewSyncMode = ( Qgs3DMapSettings::ViewSyncMode )( elemNavigationSync.attribute( QStringLiteral( "view-sync-mode" ), QStringLiteral( "0" ) ).toInt() );
+  mViewSyncMode = ( Qgis::ViewSyncMode )( elemNavigationSync.attribute( QStringLiteral( "view-sync-mode" ), QStringLiteral( "0" ) ).toInt() );
+  mVisualizeViewFrustum = elemNavigationSync.attribute( QStringLiteral( "view-frustum-visualization-enabled" ), QStringLiteral( "0" ) ).toInt();
 
   QDomElement elemDebugSettings = elem.firstChildElement( QStringLiteral( "debug-settings" ) );
   mDebugShadowMapEnabled = elemDebugSettings.attribute( QStringLiteral( "shadowmap-enabled" ), QStringLiteral( "0" ) ).toInt();
@@ -414,6 +416,7 @@ QDomElement Qgs3DMapSettings::writeXml( QDomDocument &doc, const QgsReadWriteCon
 
   QDomElement elemNavigationSync = doc.createElement( QStringLiteral( "navigation-sync" ) );
   elemNavigationSync.setAttribute( QStringLiteral( "view-sync-mode" ), ( int )mViewSyncMode );
+  elemNavigationSync.setAttribute( QStringLiteral( "view-frustum-visualization-enabled" ), mVisualizeViewFrustum ? QStringLiteral( "0" ) : QStringLiteral( "1" ) );
   elem.appendChild( elemNavigationSync );
 
   QDomElement elemDebugSettings = doc.createElement( QStringLiteral( "debug-settings" ) );
@@ -879,11 +882,21 @@ void Qgs3DMapSettings::setRendererUsage( Qgis::RendererUsage rendererUsage )
   mRendererUsage = rendererUsage;
 }
 
-void Qgs3DMapSettings::setViewSyncMode( ViewSyncMode mode )
+void Qgs3DMapSettings::setViewSyncMode( Qgis::ViewSyncMode mode )
 {
   mViewSyncMode = mode;
 }
 
+void Qgs3DMapSettings::setViewFrustumVisualizationEnabled( bool enabled )
+{
+  if ( mVisualizeViewFrustum != enabled )
+  {
+    mVisualizeViewFrustum = enabled;
+    emit viewFrustumVisualizationEnabledChanged();
+  }
+}
+
+
 void Qgs3DMapSettings::connectChangedSignalsToSettingsChanged()
 {
   connect( this, &Qgs3DMapSettings::selectionColorChanged, this, &Qgs3DMapSettings::settingsChanged );

src/3d/qgs3dmapsettings.h

@@ -57,13 +57,6 @@ class _3D_EXPORT Qgs3DMapSettings : public QObject, public QgsTemporalRangeObjec
 {
     Q_OBJECT
   public:
-    enum ViewSyncMode
-    {
-      NoSync, //! No syncronisation will happen
-      Sync3DTo2D, //! Syncronize 3D view camera to the main map canvas extent
-      Sync2DTo3D //! Update the 2D main canvas extent to include the viewed area from the 3D view
-    };
-
     //! Constructor for Qgs3DMapSettings
     Qgs3DMapSettings();
     //! Copy constructor
@@ -603,14 +596,28 @@ class _3D_EXPORT Qgs3DMapSettings : public QObject, public QgsTemporalRangeObjec
      *
      * \since QGIS 3.26
      */
-    ViewSyncMode viewSyncMode() const { return mViewSyncMode; }
+    Qgis::ViewSyncMode viewSyncMode() const { return mViewSyncMode; }
 
     /**
      * Sets the view sync mode (used to syncronize the 2D main map canvas and the 3D camera navigation)
      *
      * \since QGIS 3.26
      */
-    void setViewSyncMode( ViewSyncMode mode );
+    void setViewSyncMode( Qgis::ViewSyncMode mode );
+
+    /**
+     * Returns whether the camera's view frustum is visualized on the 2D map canvas
+     *
+     * \since QGIS 3.26
+     */
+    bool viewFrustumVisualizationEnabled() const { return mVisualizeViewFrustum; }
+
+    /**
+     * Sets whether the camera's view frustum is visualized on the 2D map canvas
+     *
+     * \since QGIS 3.26
+     */
+    void setViewFrustumVisualizationEnabled( bool enabled );
 
   signals:
 
@@ -779,6 +786,13 @@ class _3D_EXPORT Qgs3DMapSettings : public QObject, public QgsTemporalRangeObjec
      */
     void fpsCounterEnabledChanged( bool fpsCounterEnabled );
 
+    /**
+     * Emitted when the camera's view frustum visualization on the main 2D map canvas is enabled or disabled
+     *
+     * \since QGIS 3.26
+     */
+    void viewFrustumVisualizationEnabledChanged();
+
   private:
 #ifdef SIP_RUN
     Qgs3DMapSettings &operator=( const Qgs3DMapSettings & );
@@ -832,7 +846,8 @@ class _3D_EXPORT Qgs3DMapSettings : public QObject, public QgsTemporalRangeObjec
     double mEyeDomeLightingStrength = 1000.0;
     int mEyeDomeLightingDistance = 1;
 
-    ViewSyncMode mViewSyncMode = ViewSyncMode::NoSync;
+    Qgis::ViewSyncMode mViewSyncMode = Qgis::ViewSyncMode::NoSync;
+    bool mVisualizeViewFrustum = false;
 
     bool mDebugShadowMapEnabled = false;
     Qt::Corner mDebugShadowMapCorner = Qt::Corner::TopLeftCorner;

src/app/3d/qgs3dmapcanvas.cpp

@@ -353,12 +353,12 @@ void Qgs3DMapCanvas::onNavigationModeHotKeyPressed( QgsCameraController::Navigat
   mScene->cameraController()->setCameraNavigationMode( mode );
 }
 
-void Qgs3DMapCanvas::viewExtent( const QgsRectangle &extent )
+void Qgs3DMapCanvas::setViewFrom2DExtent( const QgsRectangle &extent )
 {
-  mScene->viewExtent( extent );
+  mScene->setViewFrom2DExtent( extent );
 }
 
-QgsRectangle Qgs3DMapCanvas::viewFrustum2DExtent()
+QVector<QgsPointXY> Qgs3DMapCanvas::viewFrustum2DExtent()
 {
   return mScene->viewFrustum2DExtent();
 }

src/app/3d/qgs3dmapcanvas.h

@@ -41,7 +41,7 @@ class QgsWindow3DEngine;
 class QgsPointXY;
 class Qgs3DNavigationWidget;
 class QgsTemporalController;
-
+class QgsRubberBand;
 
 class Qgs3DMapCanvas : public QWidget
 {
@@ -105,14 +105,14 @@ class Qgs3DMapCanvas : public QWidget
      *
      * \since QGIS 3.26
      */
-    void viewExtent( const QgsRectangle &extent );
+    void setViewFrom2DExtent( const QgsRectangle &extent );
 
     /**
-     * Calculates the 2D extent viewed by the 3D camera
+     * Calculates the 2D extent viewed by the 3D camera as the vertices of the viewed trapezoid
      *
      * \since QGIS 3.26
      */
-    QgsRectangle viewFrustum2DExtent();
+    QVector<QgsPointXY> viewFrustum2DExtent();
 
   signals:
     //! Emitted when the 3D map canvas was successfully saved as image
@@ -131,7 +131,7 @@ class Qgs3DMapCanvas : public QWidget
      *
      * \since QGIS 3.26
      */
-    void viewed2DExtentFrom3DChanged( QgsRectangle extent );
+    void viewed2DExtentFrom3DChanged( QVector<QgsPointXY> extent );
 
     /**
      * Emitted when the camera navigation \a speed is changed.

src/app/3d/qgs3dmapcanvaswidget.cpp

@@ -50,12 +50,14 @@
 #include "qgs3dmapexportsettings.h"
 
 #include "qgsdockablewidgethelper.h"
+#include "qgsrubberband.h"
 
 #include <QWidget>
 
 Qgs3DMapCanvasWidget::Qgs3DMapCanvasWidget( const QString &name, bool isDocked )
   : QWidget( nullptr )
   , mCanvasName( name )
+  , mViewFrustumHighlight( nullptr )
 {
   const QgsSettings setting;
 
@@ -230,6 +232,8 @@ Qgs3DMapCanvasWidget::Qgs3DMapCanvasWidget( const QString &name, bool isDocked )
 Qgs3DMapCanvasWidget::~Qgs3DMapCanvasWidget()
 {
   delete mDockableWidgetHelper;
+  if ( mViewFrustumHighlight )
+    delete mViewFrustumHighlight;
 }
 
 void Qgs3DMapCanvasWidget::resizeEvent( QResizeEvent *event )
@@ -322,6 +326,8 @@ void Qgs3DMapCanvasWidget::setMapSettings( Qgs3DMapSettings *map )
   // Disable button for switching the map theme if the terrain generator is a mesh, or if there is no terrain
   mBtnMapThemes->setDisabled( !mCanvas->map()->terrainGenerator() || mCanvas->map()->terrainGenerator()->type() == QgsTerrainGenerator::Mesh );
   mLabelFpsCounter->setVisible( map->isFpsCounterEnabled() );
+
+  connect( map, &Qgs3DMapSettings::viewFrustumVisualizationEnabledChanged, this, &Qgs3DMapCanvasWidget::onViewFrustumVisualizationEnabledChanged );
 }
 
 void Qgs3DMapCanvasWidget::setMainCanvas( QgsMapCanvas *canvas )
@@ -331,6 +337,11 @@ void Qgs3DMapCanvasWidget::setMainCanvas( QgsMapCanvas *canvas )
   connect( mMainCanvas, &QgsMapCanvas::layersChanged, this, &Qgs3DMapCanvasWidget::onMainCanvasLayersChanged );
   connect( mMainCanvas, &QgsMapCanvas::canvasColorChanged, this, &Qgs3DMapCanvasWidget::onMainCanvasColorChanged );
   connect( mMainCanvas, &QgsMapCanvas::extentsChanged, this, &Qgs3DMapCanvasWidget::onMainMapCanvasExtentChanged );
+
+  if ( mViewFrustumHighlight )
+    delete mViewFrustumHighlight;
+  mViewFrustumHighlight = new QgsRubberBand( canvas, QgsWkbTypes::PolygonGeometry );
+  mViewFrustumHighlight->setColor( QColor::fromRgba( qRgba( 0, 0, 255, 50 ) ) );
 }
 
 void Qgs3DMapCanvasWidget::resetView()
@@ -507,27 +518,50 @@ void Qgs3DMapCanvasWidget::onMainMapCanvasExtentChanged()
 {
   switch ( mCanvas->map()->viewSyncMode() )
   {
-    case Qgs3DMapSettings::NoSync:
+    case Qgis::ViewSyncMode::NoSync:
       break;
-    case Qgs3DMapSettings::Sync3DTo2D:
+    case Qgis::ViewSyncMode::Sync3DTo2D:
-      mCanvas->viewExtent( mMainCanvas->extent() );
+      mCanvas->setViewFrom2DExtent( mMainCanvas->extent() );
       break;
-    case Qgs3DMapSettings::Sync2DTo3D:
+    case Qgis::ViewSyncMode::Sync2DTo3D:
       break;
   }
 }
 
-void Qgs3DMapCanvasWidget::onViewed2DExtentFrom3DChanged( QgsRectangle extent )
+void Qgs3DMapCanvasWidget::onViewed2DExtentFrom3DChanged( QVector<QgsPointXY> extent )
 {
   switch ( mCanvas->map()->viewSyncMode() )
   {
-    case Qgs3DMapSettings::NoSync:
+    case Qgis::ViewSyncMode::NoSync:
       break;
-    case Qgs3DMapSettings::Sync3DTo2D:
+    case Qgis::ViewSyncMode::Sync3DTo2D:
       break;
-    case Qgs3DMapSettings::Sync2DTo3D:
+    case Qgis::ViewSyncMode::Sync2DTo3D:
-      mMainCanvas->setExtent( extent );
+    {
+      QgsRectangle extentRect;
+      extentRect.setMinimal();
+      for ( QgsPointXY &pt : extent )
+      {
+        extentRect.include( pt );
+      }
+      mMainCanvas->setExtent( extentRect );
       mMainCanvas->refresh();
       break;
+    }
+  }
+
+  onViewFrustumVisualizationEnabledChanged();
+}
+
+void Qgs3DMapCanvasWidget::onViewFrustumVisualizationEnabledChanged()
+{
+  mViewFrustumHighlight->reset( QgsWkbTypes::PolygonGeometry );
+  if ( mCanvas->map()->viewFrustumVisualizationEnabled() )
+  {
+    for ( QgsPointXY &pt : mCanvas->viewFrustum2DExtent() )
+    {
+      mViewFrustumHighlight->addPoint( pt, false );
+    }
+    mViewFrustumHighlight->closePoints();
   }
 }

src/app/3d/qgs3dmapcanvaswidget.h

@@ -34,6 +34,7 @@ class Qgs3DMapToolIdentify;
 class Qgs3DMapToolMeasureLine;
 class QgsMapCanvas;
 class QgsDockableWidgetHelper;
+class QgsRubberBand;
 
 class APP_EXPORT Qgs3DMapCanvasWidget : public QWidget
 {
@@ -86,7 +87,8 @@ class APP_EXPORT Qgs3DMapCanvasWidget : public QWidget
     void currentMapThemeRenamed( const QString &theme, const QString &newTheme );
 
     void onMainMapCanvasExtentChanged();
-    void onViewed2DExtentFrom3DChanged( QgsRectangle extent );
+    void onViewed2DExtentFrom3DChanged( QVector<QgsPointXY> extent );
+    void onViewFrustumVisualizationEnabledChanged();
 
   private:
     QString mCanvasName;
@@ -108,6 +110,7 @@ class APP_EXPORT Qgs3DMapCanvasWidget : public QWidget
     QAction *mActionEnableEyeDome = nullptr;
     QToolButton *mBtnOptions = nullptr;
     QgsDockableWidgetHelper *mDockableWidgetHelper = nullptr;
+    QgsRubberBand *mViewFrustumHighlight = nullptr;
 };
 
 #endif // QGS3DMAPCANVASWIDGET_H

src/app/3d/qgs3dmapconfigwidget.cpp

@@ -193,6 +193,7 @@ Qgs3DMapConfigWidget::Qgs3DMapConfigWidget( Qgs3DMapSettings *map, QgsMapCanvas
   edlDistanceSpinBox->setValue( map->eyeDomeLightingDistance() );
 
   mSyncModeComboBox->setCurrentIndex( ( int )map->viewSyncMode() );
+  mVisualizeExtentCheckBox->setChecked( map->viewFrustumVisualizationEnabled() );
 
   mDebugShadowMapCornerComboBox->addItem( tr( "Top Left" ) );
   mDebugShadowMapCornerComboBox->addItem( tr( "Top Right" ) );
@@ -360,7 +361,8 @@ void Qgs3DMapConfigWidget::apply()
   mMap->setEyeDomeLightingStrength( edlStrengthSpinBox->value() );
   mMap->setEyeDomeLightingDistance( edlDistanceSpinBox->value() );
 
-  mMap->setViewSyncMode( static_cast<Qgs3DMapSettings::ViewSyncMode>( mSyncModeComboBox->currentIndex() ) );
+  mMap->setViewSyncMode( static_cast<Qgis::ViewSyncMode>( mSyncModeComboBox->currentIndex() ) );
+  mMap->setViewFrustumVisualizationEnabled( mVisualizeExtentCheckBox->isChecked() );
 
   mMap->setDebugDepthMapSettings( mDebugDepthMapGroupBox->isChecked(), static_cast<Qt::Corner>( mDebugDepthMapCornerComboBox->currentIndex() ), mDebugDepthMapSizeSpinBox->value() );
   mMap->setDebugShadowMapSettings( mDebugShadowMapGroupBox->isChecked(), static_cast<Qt::Corner>( mDebugShadowMapCornerComboBox->currentIndex() ), mDebugShadowMapSizeSpinBox->value() );

src/core/qgis.h

@@ -1373,6 +1373,15 @@ class CORE_EXPORT Qgis
     };
     Q_ENUM( RendererUsage )
 
+    enum class ViewSyncMode : int
+    {
+      NoSync = 0, //! No syncronisation will happen
+      Sync3DTo2D = 1, //! Syncronize 3D view camera to the main map canvas extent
+      Sync2DTo3D = 2,  //! Update the 2D main canvas extent to include the viewed area from the 3D view
+      BothWaysSync = 3
+    };
+    Q_ENUM( ViewSyncMode )
+
     /**
      * History provider backends.
      *

src/ui/3d/map3dconfigwidget.ui

@@ -94,7 +94,7 @@
            <string>Terrain settings</string>
           </property>
           <property name="icon">
-           <iconset resource="../../../images/images.qrc">
+           <iconset>
             <normaloff>:/images/themes/default/mLayoutItem3DMap.svg</normaloff>:/images/themes/default/mLayoutItem3DMap.svg</iconset>
           </property>
          </item>
@@ -106,7 +106,7 @@
            <string>Lights settings</string>
           </property>
           <property name="icon">
-           <iconset resource="../../../images/images.qrc">
+           <iconset>
             <normaloff>:/images/themes/default/mActionHighlightFeature.svg</normaloff>:/images/themes/default/mActionHighlightFeature.svg</iconset>
           </property>
          </item>
@@ -118,7 +118,7 @@
            <string>Shadow settings</string>
           </property>
           <property name="icon">
-           <iconset resource="../../../images/images.qrc">
+           <iconset>
             <normaloff>:/images/themes/default/mIconShadow.svg</normaloff>:/images/themes/default/mIconShadow.svg</iconset>
           </property>
          </item>
@@ -130,7 +130,7 @@
            <string>Camera and skybox settings</string>
           </property>
           <property name="icon">
-           <iconset resource="../../../images/images.qrc">
+           <iconset>
             <normaloff>:/images/themes/default/mIconCamera.svg</normaloff>:/images/themes/default/mIconCamera.svg</iconset>
           </property>
          </item>
@@ -147,7 +147,7 @@
            <string>Advanced settings</string>
           </property>
           <property name="icon">
-           <iconset resource="../../../images/images.qrc">
+           <iconset>
             <normaloff>:/images/themes/default/propertyicons/system.svg</normaloff>:/images/themes/default/propertyicons/system.svg</iconset>
           </property>
          </item>
@@ -184,7 +184,7 @@
        <item>
         <widget class="QStackedWidget" name="m3DOptionsStackedWidget">
          <property name="currentIndex">
-          <number>4</number>
+          <number>5</number>
          </property>
          <widget class="QWidget" name="mPageTerrain">
           <layout class="QVBoxLayout" name="verticalLayout_61">
@@ -421,7 +421,7 @@
                <rect>
                 <x>0</x>
                 <y>0</y>
-                <width>98</width>
+                <width>77</width>
                 <height>43</height>
                </rect>
               </property>
@@ -595,8 +595,8 @@
                <rect>
                 <x>0</x>
                 <y>0</y>
-                <width>234</width>
+                <width>721</width>
-                <height>220</height>
+                <height>604</height>
                </rect>
               </property>
               <layout class="QVBoxLayout" name="verticalLayoutCameraSkybox">
@@ -723,11 +723,31 @@
                <rect>
                 <x>0</x>
                 <y>0</y>
-                <width>707</width>
+                <width>710</width>
                 <height>584</height>
                </rect>
               </property>
               <layout class="QGridLayout" name="gridLayout_7">
+               <item row="2" column="1">
+                <spacer name="verticalSpacer">
+                 <property name="orientation">
+                  <enum>Qt::Vertical</enum>
+                 </property>
+                 <property name="sizeHint" stdset="0">
+                  <size>
+                   <width>20</width>
+                   <height>40</height>
+                  </size>
+                 </property>
+                </spacer>
+               </item>
+               <item row="0" column="0">
+                <widget class="QLabel" name="label_3">
+                 <property name="text">
+                  <string>Sync mode</string>
+                 </property>
+                </widget>
+               </item>
                <item row="0" column="1">
                 <widget class="QComboBox" name="mSyncModeComboBox">
                  <item>
@@ -747,23 +767,10 @@
                  </item>
                 </widget>
                </item>
-               <item row="1" column="1">
+               <item row="1" column="0" colspan="2">
-                <spacer name="verticalSpacer">
+                <widget class="QCheckBox" name="mVisualizeExtentCheckBox">
-                 <property name="orientation">
-                  <enum>Qt::Vertical</enum>
-                 </property>
-                 <property name="sizeHint" stdset="0">
-                  <size>
-                   <width>20</width>
-                   <height>40</height>
-                  </size>
-                 </property>
-                </spacer>
-               </item>
-               <item row="0" column="0">
-                <widget class="QLabel" name="label_3">
                  <property name="text">
-                  <string>Sync mode</string>
+                  <string>Visualize viewed 3D area in main 2D map canvas</string>
                  </property>
                 </widget>
                </item>
@@ -797,7 +804,7 @@
                <rect>
                 <x>0</x>
                 <y>0</y>
-                <width>408</width>
+                <width>707</width>
                 <height>690</height>
                </rect>
               </property>
@@ -1199,9 +1206,6 @@
   <tabstop>mDebugDepthMapCornerComboBox</tabstop>
   <tabstop>mDebugDepthMapSizeSpinBox</tabstop>
  </tabstops>
- <resources>
+ <resources/>
-  <include location="../../../images/images.qrc"/>
-  <include location="../../../images/images.qrc"/>
- </resources>
  <connections/>
 </ui>