qgs3daxis: Define only only one viewport in the framegraph

The axis framegraph has two distinct branches : one for the main
object (the axis or the cube) and one for the axis labels. Each of
those branches have a dedicated viewport. However, only one viewport
is needed since the two branches need the same part of the
window.

With this change, the first node of the axis' framegraph is now the
viewport (mViewport) and the two branches inherit from it:

- viewport
  <-- object branch -->
  - layerfilter (axisLayerFilter)
  - cameraselector
  - sortPolicy
  - clearBuffers

  <-- labels branch -->
  - layerfilter (twoDLayerFilter)
  - cameraselector
  - sortPolicy
  - clearBuffers

`from3DTo2DLabelPosition()` is also simplified to compute the
billboard position of the axis labels. Indeed, the viewport of the
labels had the dimensions of the main window (0, 0, 1, 1) while the
objects viewport has only the dimensions the relevant part of the
window. Therefore, `from3DTo2DLabelPosition()` needed to take into
this into account and recenter the computer coordinates. This is not
needed anymore.

src/3d/qgs3daxis.cpp

@@ -55,11 +55,10 @@ Qgs3DAxis::Qgs3DAxis( Qgs3DMapCanvas *canvas,
   , mCameraController( cameraCtrl )
   , mCrs( map->crs() )
 {
-  mAxisViewport = constructAxisViewport( parent3DScene );
-  mAxisViewport->setParent( mCanvas->activeFrameGraph() );
+  mViewport = constructAxisScene( parent3DScene );
+  mViewport->setParent( mCanvas->activeFrameGraph() );
 
-  mTwoDLabelViewport = constructLabelViewport( parent3DScene, QRectF( 0.0f, 0.0f, 1.0f, 1.0f ) );
-  mTwoDLabelViewport->setParent( mCanvas->activeFrameGraph() );
+  constructLabelsScene( parent3DScene );
 
   connect( cameraCtrl, &QgsCameraController::cameraChanged, this, &Qgs3DAxis::onCameraUpdate );
   connect( mCanvas, &Qgs3DMapCanvas::widthChanged, this, &Qgs3DAxis::onAxisViewportSizeUpdate );
@@ -142,11 +141,11 @@ bool Qgs3DAxis::eventFilter( QObject *watched, QEvent *event )
       if ( 2 <= QgsLogger::debugLevel() && event->type() == QEvent::MouseButtonRelease )
       {
         std::ostringstream os;
-        os << "QGS3DAxis: normalized pos: " << normalizedPos << " / viewport: " << mAxisViewport->normalizedRect();
+        os << "QGS3DAxis: normalized pos: " << normalizedPos << " / viewport: " << mViewport->normalizedRect();
         QgsDebugMsgLevel( os.str().c_str(), 2 );
       }
 
-      if ( mAxisViewport->normalizedRect().contains( normalizedPos ) )
+      if ( mViewport->normalizedRect().contains( normalizedPos ) )
       {
         mLastClickedButton = mouseEvent->button();
         mLastClickedPos = mouseEvent->pos();
@@ -286,7 +285,7 @@ void Qgs3DAxis::onTouchedByRay( const Qt3DRender::QAbstractRayCaster::Hits &hits
   }
 }
 
-Qt3DRender::QViewport *Qgs3DAxis::constructAxisViewport( Qt3DCore::QEntity *parent3DScene )
+Qt3DRender::QViewport *Qgs3DAxis::constructAxisScene( Qt3DCore::QEntity *parent3DScene )
 {
   Qt3DRender::QViewport *axisViewport = new Qt3DRender::QViewport;
   // parent will be set later
@@ -331,23 +330,16 @@ Qt3DRender::QViewport *Qgs3DAxis::constructAxisViewport( Qt3DCore::QEntity *pare
   return axisViewport;
 }
 
-Qt3DRender::QViewport *Qgs3DAxis::constructLabelViewport( Qt3DCore::QEntity *parent3DScene, const QRectF &parentViewportSize )
+void Qgs3DAxis::constructLabelsScene( Qt3DCore::QEntity *parent3DScene )
 {
-  Qt3DRender::QViewport *twoDViewport = new Qt3DRender::QViewport;
-  // parent will be set later
-  twoDViewport->setNormalizedRect( parentViewportSize );
-
   mTwoDLabelSceneEntity = new Qt3DCore::QEntity;
   mTwoDLabelSceneEntity->setParent( parent3DScene );
   mTwoDLabelSceneEntity->setEnabled( true );
 
   mTwoDLabelCamera = new Qt3DRender::QCamera;
   mTwoDLabelCamera->setParent( mTwoDLabelSceneEntity );
   mTwoDLabelCamera->setProjectionType( Qt3DRender::QCameraLens::ProjectionType::OrthographicProjection );
-  mTwoDLabelCamera->lens()->setOrthographicProjection(
-    -mCanvas->width() / 2.0f, mCanvas->width() / 2.0f,
-    -mCanvas->height() / 2.0f, mCanvas->height() / 2.0f,
-    -10.0f, 100.0f );
+  // the camera lens parameters are defined by onAxisViewportSizeUpdate()
 
   mTwoDLabelCamera->setUpVector( QVector3D( 0.0f, 0.0f, 1.0f ) );
   mTwoDLabelCamera->setViewCenter( QVector3D( 0.0f, 0.0f, 0.0f ) );
@@ -359,7 +351,7 @@ Qt3DRender::QViewport *Qgs3DAxis::constructLabelViewport( Qt3DCore::QEntity *par
   twoDLayer->setRecursive( true );
   mTwoDLabelSceneEntity->addComponent( twoDLayer );
 
-  Qt3DRender::QLayerFilter *twoDLayerFilter = new Qt3DRender::QLayerFilter( twoDViewport );
+  Qt3DRender::QLayerFilter *twoDLayerFilter = new Qt3DRender::QLayerFilter;
   twoDLayerFilter->addLayer( twoDLayer );
 
   Qt3DRender::QCameraSelector *twoDCameraSelector = new Qt3DRender::QCameraSelector;
@@ -376,40 +368,18 @@ Qt3DRender::QViewport *Qgs3DAxis::constructLabelViewport( Qt3DCore::QEntity *par
   Qt3DRender::QClearBuffers *clearBuffers = new Qt3DRender::QClearBuffers( sortPolicy );
   clearBuffers->setBuffers( Qt3DRender::QClearBuffers::DepthBuffer );
 
-  // cppcheck-suppress memleak
-  return twoDViewport;
+  twoDLayerFilter->setParent( mViewport );
 }
 
-QVector3D Qgs3DAxis::from3DTo2DLabelPosition( const QVector3D &sourcePos,
-    Qt3DRender::QCamera *sourceCamera, Qt3DRender::QViewport *sourceViewport,
-    Qt3DRender::QCamera *destCamera, Qt3DRender::QViewport *destViewport,
-    const QSize &destSize )
+QVector3D Qgs3DAxis::from3DTo2DLabelPosition( const QVector3D &sourcePos, Qt3DRender::QCamera *sourceCamera, Qt3DRender::QCamera *destCamera )
 {
-  QVector3D destPos = sourcePos.project( sourceCamera->viewMatrix(),
-                                         destCamera->projectionMatrix(),
-                                         QRect( 0.0f, 0.0f,
-                                             destViewport->normalizedRect().width() * destSize.width(),
-                                             destViewport->normalizedRect().height() * destSize.height() ) );
-  QPointF axisCenter = sourceViewport->normalizedRect().center();
-  QPointF labelCenter = destViewport->normalizedRect().center();
-  QVector3D viewTranslation = QVector3D( ( axisCenter - labelCenter ).x() * destSize.width(),
-                                         ( axisCenter - labelCenter ).y() * destSize.height(),
-                                         0.0f );
-  destPos -= QVector3D( labelCenter.x() * destSize.width(),
-                        labelCenter.y() * destSize.height(),
-                        0.0f );
-  destPos.setX( destPos.x() + viewTranslation.x() );
-  destPos.setY( destPos.y() - viewTranslation.y() );
-  destPos.setZ( 0.0f );
+  const int viewportWidth = static_cast<int>( std::round( mTwoDLabelCamera->lens()->right() - mTwoDLabelCamera->lens()->left() ) );
+  const int viewportHeight = static_cast<int>( std::round( mTwoDLabelCamera->lens()->top() - mTwoDLabelCamera->lens()->bottom() ) );
+  QRect viewportRect( static_cast<int>( std::round( mTwoDLabelCamera->lens()->left() ) ), static_cast<int>( std::round( mTwoDLabelCamera->lens()->bottom() ) ),
+                      viewportWidth, viewportHeight );
 
-  if ( 2 <= QgsLogger::debugLevel() )
-  {
-    std::ostringstream os;
-    os << "Qgs3DAxis::from3DTo2DLabelPosition: sourcePos: " << sourcePos.toPoint()
-       << " with translation: " << viewTranslation.toPoint()
-       << " corrected to pos: " << destPos.toPoint();
-    QgsDebugMsgLevel( os.str().c_str(), 2 );
-  }
+  QVector3D destPos = sourcePos.project( sourceCamera->viewMatrix(), destCamera->projectionMatrix(), viewportRect );
+  destPos.setZ( 0.0f );
   return destPos;
 }
 
@@ -1096,7 +1066,7 @@ void Qgs3DAxis::onAxisViewportSizeUpdate( int )
   {
     QgsDebugMsgLevel( "viewport takes too much place into the 3d view, disabling it", 2 );
     // take too much place into the 3d view
-    mAxisViewport->setEnabled( false );
+    mViewport->setEnabled( false );
     setEnableCube( false );
     setEnableAxis( false );
   }
@@ -1106,14 +1076,14 @@ void Qgs3DAxis::onAxisViewportSizeUpdate( int )
     mAxisScaleFactor = viewportPixelSize / defaultViewportPixelSize;
     QgsDebugMsgLevel( QString( "3DAxis viewport mAxisScaleFactor %1" ).arg( mAxisScaleFactor ), 2 );
 
-    if ( ! mAxisViewport->isEnabled() )
+    if ( ! mViewport->isEnabled() )
     {
       if ( settings.mode() == Qgs3DAxisSettings::Mode::Crs )
         setEnableAxis( true );
       else if ( settings.mode() == Qgs3DAxisSettings::Mode::Cube )
         setEnableCube( true );
     }
-    mAxisViewport->setEnabled( true );
+    mViewport->setEnabled( true );
 
     float xRatio = 1.0f;
     float yRatio = 1.0f;
@@ -1132,13 +1102,15 @@ void Qgs3DAxis::onAxisViewportSizeUpdate( int )
       yRatio = 1.0f - heightRatio;
 
     QgsDebugMsgLevel( QString( "Qgs3DAxis: update viewport: %1 x %2 x %3 x %4" ).arg( xRatio ).arg( yRatio ).arg( widthRatio ).arg( heightRatio ), 2 );
-    mAxisViewport->setNormalizedRect( QRectF( xRatio, yRatio, widthRatio, heightRatio ) );
+    mViewport->setNormalizedRect( QRectF( xRatio, yRatio, widthRatio, heightRatio ) );
 
     if ( settings.mode() == Qgs3DAxisSettings::Mode::Crs )
     {
+      const float halfWidthSize = static_cast<float>( windowWidth * widthRatio / 2.0 );
+      const float halfHeightSize = static_cast<float>( windowWidth * widthRatio / 2.0 );
       mTwoDLabelCamera->lens()->setOrthographicProjection(
-        -windowWidth / 2.0f, windowWidth / 2.0f,
-        -windowHeight / 2.0f, windowHeight / 2.0f,
+        -halfWidthSize, halfWidthSize,
+        -halfHeightSize, halfHeightSize,
         mTwoDLabelCamera->lens()->nearPlane(), mTwoDLabelCamera->lens()->farPlane() );
 
       updateAxisLabelPosition();
@@ -1182,19 +1154,13 @@ void Qgs3DAxis::updateAxisLabelPosition()
 {
   if ( mTextTransformX && mTextTransformY && mTextTransformZ )
   {
-    mTextTransformX->setTranslation( from3DTo2DLabelPosition( mTextCoordX * mAxisScaleFactor, mAxisCamera,
-                                     mAxisViewport, mTwoDLabelCamera, mTwoDLabelViewport,
-                                     mCanvas->size() ) );
+    mTextTransformX->setTranslation( from3DTo2DLabelPosition( mTextCoordX * static_cast<float>( mAxisScaleFactor ), mAxisCamera, mTwoDLabelCamera ) );
     updateAxisLabelText( mTextX, mTextX->text() );
 
-    mTextTransformY->setTranslation( from3DTo2DLabelPosition( mTextCoordY * mAxisScaleFactor, mAxisCamera,
-                                     mAxisViewport, mTwoDLabelCamera, mTwoDLabelViewport,
-                                     mCanvas->size() ) );
+    mTextTransformY->setTranslation( from3DTo2DLabelPosition( mTextCoordY * static_cast<float>( mAxisScaleFactor ), mAxisCamera, mTwoDLabelCamera ) );
     updateAxisLabelText( mTextY, mTextY->text() );
 
-    mTextTransformZ->setTranslation( from3DTo2DLabelPosition( mTextCoordZ * mAxisScaleFactor, mAxisCamera,
-                                     mAxisViewport, mTwoDLabelCamera, mTwoDLabelViewport,
-                                     mCanvas->size() ) );
+    mTextTransformZ->setTranslation( from3DTo2DLabelPosition( mTextCoordZ * static_cast<float>( mAxisScaleFactor ), mAxisCamera, mTwoDLabelCamera ) );
     updateAxisLabelText( mTextZ, mTextZ->text() );
   }
 }

src/3d/qgs3daxis.h

@@ -69,20 +69,15 @@ class _3D_EXPORT Qgs3DAxis : public QObject
     ~Qgs3DAxis() override;
 
     /**
-     * \brief project a 3D position from sourceCamera (in sourceViewport) to a 2D position for destCamera (in destViewport). destCamera and the destViewport act as a billboarding layer. The labels displayed by this process will always face the camera.
+     * \brief project a 3D position from sourceCamera to a 2D position for destCamera. destCamera acts as a billboarding layer. The labels displayed by this process will always face the camera.
      *
      * \param sourcePos 3D label coordinates
      * @param sourceCamera main view camera
-     * @param sourceViewport main viewport
      * @param destCamera billboarding camera
-     * @param destViewport billboarding viewport
-     * @param destSize main qt3d window size
      * @return
      */
-    QVector3D from3DTo2DLabelPosition( const QVector3D &sourcePos,
-                                       Qt3DRender::QCamera *sourceCamera, Qt3DRender::QViewport *sourceViewport,
-                                       Qt3DRender::QCamera *destCamera, Qt3DRender::QViewport *destViewport,
-                                       const QSize &destSize );
+    QVector3D from3DTo2DLabelPosition( const QVector3D &sourcePos, Qt3DRender::QCamera *sourceCamera, Qt3DRender::QCamera *destCamera );
+
 
   public slots:
 
@@ -121,8 +116,8 @@ class _3D_EXPORT Qgs3DAxis : public QObject
     void updateAxisLabelText( Qt3DExtras::QText2DEntity *textEntity, const QString &text );
     QFont createFont( int pointSize );
 
-    Qt3DRender::QViewport *constructAxisViewport( Qt3DCore::QEntity *parent3DScene );
-    Qt3DRender::QViewport *constructLabelViewport( Qt3DCore::QEntity *parent3DScene, const QRectF &parentViewportSize );
+    Qt3DRender::QViewport *constructAxisScene( Qt3DCore::QEntity *parent3DScene );
+    void constructLabelsScene( Qt3DCore::QEntity *parent3DScene );
 
     Qt3DExtras::QText2DEntity *addCubeText( const QString &text, float textHeight, float textWidth, const QFont &font, const QMatrix4x4 &rotation, const QVector3D &translation );
 
@@ -142,10 +137,11 @@ class _3D_EXPORT Qgs3DAxis : public QObject
     float mCylinderLength = 40.0f;
     int mFontSize = 12;
 
+    Qt3DRender::QViewport *mViewport = nullptr;
+
     Qt3DCore::QEntity *mAxisSceneEntity = nullptr;
     Qt3DRender::QLayer *mAxisObjectLayer = nullptr;
     Qt3DRender::QCamera *mAxisCamera = nullptr;
-    Qt3DRender::QViewport *mAxisViewport = nullptr;
 
     Qt3DCore::QEntity *mAxisRoot = nullptr;
     Qt3DCore::QEntity *mCubeRoot = nullptr;
@@ -166,7 +162,6 @@ class _3D_EXPORT Qgs3DAxis : public QObject
 
     Qt3DRender::QCamera *mTwoDLabelCamera  = nullptr;
     Qt3DCore::QEntity *mTwoDLabelSceneEntity = nullptr;
-    Qt3DRender::QViewport *mTwoDLabelViewport = nullptr;
 
     // axis picking and menu
     Qt3DRender::QScreenRayCaster *mScreenRayCaster = nullptr;