Change how "Get Z value from project terrain" tool is presented in Mesh Editing

python/PyQt6/core/auto_generated/mesh/qgsmeshadvancedediting.sip.in

@@ -137,7 +137,7 @@ Sets the expressions for the coordinates transformation.
    Expressions are optional for each coordinate, the coordinate will not be transformed if the string is void.
 %End
 
-    bool calculate( QgsMeshLayer *layer );
+    bool calculate( QgsMeshLayer *layer, QgsProject *project = 0 );
 %Docstring
 Calculates the transformed vertices of the mesh ``layer``, returns ``False`` if this leads to topological or geometrical errors.
 The mesh layer must be in edit mode.
@@ -146,13 +146,26 @@ The mesh layer must be in edit mode.
 
    this method not apply new vertices to the mesh layer but only store the calculated transformation
    that can be apply later with :py:func:`QgsMeshEditor.advancedEdit()`
+
+:param layer:
+
+.. versionadded:: 3.44
 %End
 
     QgsMeshVertex transformedVertex( QgsMeshLayer *layer, int vertexIndex ) const;
 %Docstring
 Returns the transformed vertex from its index ``vertexIndex`` for the mesh ``layer``
 
 If ``layer`` is not the same than the one used to make the calculation, this will create an undefined behavior
+%End
+
+    void setZFromTerrain( bool enable );
+%Docstring
+Sets if Z values for vertices should be obtained from project terrain, instead of expression.
+
+:param enable:
+
+.. versionadded:: 3.44
 %End
 
 };

python/core/auto_generated/mesh/qgsmeshadvancedediting.sip.in

@@ -137,7 +137,7 @@ Sets the expressions for the coordinates transformation.
    Expressions are optional for each coordinate, the coordinate will not be transformed if the string is void.
 %End
 
-    bool calculate( QgsMeshLayer *layer );
+    bool calculate( QgsMeshLayer *layer, QgsProject *project = 0 );
 %Docstring
 Calculates the transformed vertices of the mesh ``layer``, returns ``False`` if this leads to topological or geometrical errors.
 The mesh layer must be in edit mode.
@@ -146,13 +146,26 @@ The mesh layer must be in edit mode.
 
    this method not apply new vertices to the mesh layer but only store the calculated transformation
    that can be apply later with :py:func:`QgsMeshEditor.advancedEdit()`
+
+:param layer:
+
+.. versionadded:: 3.44
 %End
 
     QgsMeshVertex transformedVertex( QgsMeshLayer *layer, int vertexIndex ) const;
 %Docstring
 Returns the transformed vertex from its index ``vertexIndex`` for the mesh ``layer``
 
 If ``layer`` is not the same than the one used to make the calculation, this will create an undefined behavior
+%End
+
+    void setZFromTerrain( bool enable );
+%Docstring
+Sets if Z values for vertices should be obtained from project terrain, instead of expression.
+
+:param enable:
+
+.. versionadded:: 3.44
 %End
 
 };

src/app/mesh/qgsmeshtransformcoordinatesdockwidget.cpp

@@ -56,7 +56,16 @@ QgsMeshTransformCoordinatesDockWidget::QgsMeshTransformCoordinatesDockWidget( QW
   connect( mButtonPreview, &QToolButton::clicked, this, &QgsMeshTransformCoordinatesDockWidget::calculate );
   connect( mButtonApply, &QPushButton::clicked, this, &QgsMeshTransformCoordinatesDockWidget::apply );
   connect( mButtonImport, &QToolButton::toggled, this, &QgsMeshTransformCoordinatesDockWidget::onImportVertexClicked );
-  connect( mGetZValuesButton, &QPushButton::clicked, this, &QgsMeshTransformCoordinatesDockWidget::updateZValuesFromTerrain );
+
+  connect( mCheckBoxZ, &QCheckBox::toggled, this, [=]( const bool checked ) {
+    if ( checked )
+      mCheckBoxZFromProjectTerrain->setChecked( !checked );
+  } );
+  connect( mCheckBoxZFromProjectTerrain, &QCheckBox::toggled, this, [=]( const bool checked ) {
+    if ( checked )
+      mCheckBoxZ->setChecked( !checked );
+  } );
+  connect( mCheckBoxZFromProjectTerrain, &QCheckBox::toggled, this, &QgsMeshTransformCoordinatesDockWidget::updateButton );
 }
 
 QgsExpressionContext QgsMeshTransformCoordinatesDockWidget::createExpressionContext() const
@@ -104,8 +113,6 @@ void QgsMeshTransformCoordinatesDockWidget::setInput( QgsMeshLayer *layer, const
     }
   }
 
-  mGetZValuesButton->setDisabled( vertexIndexes.empty() );
-
   importVertexCoordinates();
   updateButton();
   emit calculationUpdated();
@@ -120,10 +127,13 @@ void QgsMeshTransformCoordinatesDockWidget::calculate()
   mTransformVertices.clear();
   mTransformVertices.setInputVertices( mInputVertices );
   mTransformVertices.setExpressions( mCheckBoxX->isChecked() ? mExpressionEditX->expression() : QString(), mCheckBoxY->isChecked() ? mExpressionEditY->expression() : QString(), mCheckBoxZ->isChecked() ? mExpressionEditZ->expression() : QString() );
-  QgsExpressionContext context;
-  context.appendScope( QgsExpressionContextUtils::projectScope( QgsProject::instance() ) );
 
-  mIsResultValid = mTransformVertices.calculate( mInputLayer );
+  if ( mCheckBoxZFromProjectTerrain->isChecked() )
+  {
+    mTransformVertices.setZFromTerrain( mCheckBoxZFromProjectTerrain->isChecked() );
+  }
+
+  mIsResultValid = mTransformVertices.calculate( mInputLayer, QgsProject::instance() );
 
   mIsCalculated = true;
   mButtonApply->setEnabled( mIsResultValid );
@@ -133,6 +143,7 @@ void QgsMeshTransformCoordinatesDockWidget::calculate()
 
 void QgsMeshTransformCoordinatesDockWidget::updateButton()
 {
+  bool modifyXYZSelected = false;
   mButtonApply->setEnabled( false );
   bool isCalculable = mInputLayer && !mInputVertices.isEmpty();
   if ( isCalculable )
@@ -141,6 +152,11 @@ void QgsMeshTransformCoordinatesDockWidget::updateButton()
     for ( const QCheckBox *cb : std::as_const( mCheckBoxes ) )
       isCalculable |= cb->isChecked();
 
+    if ( isCalculable )
+    {
+      modifyXYZSelected = true;
+    }
+
     if ( isCalculable )
     {
       for ( int i = 0; i < mCheckBoxes.count(); ++i )
@@ -149,6 +165,11 @@ void QgsMeshTransformCoordinatesDockWidget::updateButton()
         isCalculable &= !checked || mExpressionLineEdits.at( i )->isValidExpression();
       }
     }
+
+    if ( !modifyXYZSelected && mCheckBoxZFromProjectTerrain->isChecked() )
+    {
+      isCalculable = true;
+    }
   }
 
   mButtonPreview->setEnabled( isCalculable );
@@ -163,56 +184,6 @@ void QgsMeshTransformCoordinatesDockWidget::apply()
   emit applied();
 }
 
-void QgsMeshTransformCoordinatesDockWidget::updateZValuesFromTerrain()
-{
-  if ( mInputVertices.empty() )
-    return;
-
-  QList<int> modifiedVerticesIndexes;
-  QList<double> newZValues;
-
-  const QgsAbstractTerrainProvider *terrainProvider = QgsProject::instance()->elevationProperties()->terrainProvider();
-
-  if ( terrainProvider == nullptr )
-    return;
-
-  const QgsCoordinateTransform transformation = QgsCoordinateTransform( mInputLayer->crs(), terrainProvider->crs(), QgsProject::instance() );
-
-  QgsPointXY point;
-  bool vertexTransformed;
-  double elevation;
-
-  for ( int i = 0; i < mInputVertices.count(); i++ )
-  {
-    const int vertexIndex = mInputVertices.at( i );
-    const QgsPoint vertex = mInputLayer->nativeMesh()->vertex( vertexIndex );
-
-    try
-    {
-      point = transformation.transform( vertex.x(), vertex.y() );
-      vertexTransformed = true;
-    }
-    catch ( const QgsCsException & )
-    {
-      vertexTransformed = false;
-    }
-
-    if ( vertexTransformed )
-    {
-      elevation = terrainProvider->heightAt( point.x(), point.y() );
-      if ( !std::isnan( elevation ) )
-      {
-        modifiedVerticesIndexes.push_back( vertexIndex );
-        newZValues.push_back( elevation );
-      }
-    }
-  }
-
-  emit aboutToBeApplied();
-  mInputLayer->meshEditor()->changeZValues( modifiedVerticesIndexes, newZValues );
-  emit applied();
-}
-
 void QgsMeshTransformCoordinatesDockWidget::onImportVertexClicked( bool checked )
 {
   if ( checked )

src/app/mesh/qgsmeshtransformcoordinatesdockwidget.h

@@ -48,13 +48,6 @@ class APP_EXPORT QgsMeshTransformCoordinatesDockWidget : public QgsDockWidget, p
     //! Returns whether the calculation has been done
     bool isCalculated() const;
 
-    /**
-     * Updates Z values of selected vertices from QGIS project terrain provider
-     *
-     * \since QGIS 3.42
-     */
-    void updateZValuesFromTerrain();
-
   signals:
     //! Emitted when the calculation of the transform is done
     void calculationUpdated();

src/core/mesh/qgsmeshadvancedediting.cpp

@@ -22,7 +22,9 @@
 #include "qgsmeshlayer.h"
 #include "qgsexpression.h"
 #include "qgsexpressioncontextutils.h"
-
+#include "qgsproject.h"
+#include "qgsprojectelevationproperties.h"
+#include "qgsterrainprovider.h"
 
 QgsMeshAdvancedEditing::QgsMeshAdvancedEditing() = default;
 
@@ -610,7 +612,7 @@ QString QgsMeshEditRefineFaces::text() const
   return QObject::tr( "Refine %n face(s)", nullptr, mInputFaces.count() );
 }
 
-bool QgsMeshTransformVerticesByExpression::calculate( QgsMeshLayer *layer )
+bool QgsMeshTransformVerticesByExpression::calculate( QgsMeshLayer *layer, QgsProject *project )
 {
   if ( !layer || !layer->meshEditor() || !layer->nativeMesh() )
     return false;
@@ -657,14 +659,29 @@ bool QgsMeshTransformVerticesByExpression::calculate( QgsMeshLayer *layer )
   }
 
   QgsExpression expressionZ;
-  if ( calcZ )
+  if ( calcZ || mZFromTerrain )
   {
     expressionZ = QgsExpression( mExpressionZ );
     expressionZ.prepare( &context );
     mNewZValues.reserve( inputCount );
     mOldZValues.reserve( inputCount );
   }
 
+  QgsCoordinateTransform transformation;
+  const QgsAbstractTerrainProvider *terrainProvider = nullptr;
+
+  if ( mZFromTerrain )
+  {
+    if ( project )
+    {
+      terrainProvider = project->elevationProperties()->terrainProvider();
+      if ( terrainProvider )
+      {
+        transformation = QgsCoordinateTransform( layer->crs(), terrainProvider->crs(), project );
+      }
+    }
+  }
+
   for ( int i = 0; i < mInputVertices.count(); ++i )
   {
     const int vertexIndex = mInputVertices.at( i );
@@ -721,7 +738,7 @@ bool QgsMeshTransformVerticesByExpression::calculate( QgsMeshLayer *layer )
         return false;
     }
 
-    if ( calcZ )
+    if ( calcZ && !mZFromTerrain )
     {
       double z = std::numeric_limits<double>::quiet_NaN();
       if ( zvar.isValid() )
@@ -734,6 +751,38 @@ bool QgsMeshTransformVerticesByExpression::calculate( QgsMeshLayer *layer )
       mNewZValues.append( z );
       mOldZValues.append( vert.z() );
     }
+
+    if ( mZFromTerrain )
+    {
+      if ( terrainProvider )
+      {
+        QgsPointXY point;
+        bool vertexTransformed;
+        double elevation;
+
+        try
+        {
+          point = transformation.transform( vert.x(), vert.y() );
+          vertexTransformed = true;
+        }
+        catch ( const QgsCsException & )
+        {
+          vertexTransformed = false;
+        }
+
+        if ( vertexTransformed )
+        {
+          elevation = terrainProvider->heightAt( point.x(), point.y() );
+          // if elevation at terrain provider is NaN, use the original vertex Z value
+          if ( std::isnan( elevation ) )
+          {
+            elevation = vert.z();
+          }
+          mNewZValues.append( elevation );
+          mOldZValues.append( vert.z() );
+        }
+      }
+    }
   }
 
   auto transformFunction = [this, layer ]( int vi )-> const QgsMeshVertex
@@ -789,3 +838,8 @@ QgsMeshVertex QgsMeshTransformVerticesByExpression::transformedVertex( QgsMeshLa
   else
     return layer->nativeMesh()->vertex( vertexIndex );
 }
+
+void QgsMeshTransformVerticesByExpression::setZFromTerrain( bool enable )
+{
+  mZFromTerrain = enable;
+}

src/core/mesh/qgsmeshadvancedediting.h

@@ -180,8 +180,11 @@ class CORE_EXPORT QgsMeshTransformVerticesByExpression : public QgsMeshAdvancedE
      *
      * \note this method not apply new vertices to the mesh layer but only store the calculated transformation
      *       that can be apply later with QgsMeshEditor::advancedEdit()
+     *
+     * \param layer
+     * \param project QgsProject if it is necessary for the calculation ( for example with \see setZFromTerrain() ) \since QGIS 3.44
      */
-    bool calculate( QgsMeshLayer *layer );
+    bool calculate( QgsMeshLayer *layer, QgsProject *project = nullptr );
 
     /**
      * Returns the transformed vertex from its index \a vertexIndex for the mesh \a layer
@@ -190,11 +193,21 @@ class CORE_EXPORT QgsMeshTransformVerticesByExpression : public QgsMeshAdvancedE
      */
     QgsMeshVertex transformedVertex( QgsMeshLayer *layer, int vertexIndex ) const;
 
+    /**
+     * Sets if Z values for vertices should be obtained from project terrain, instead of expression.
+     *
+     * \param enable
+     *
+     * \since QGIS 3.44
+     */
+    void setZFromTerrain( bool enable );
+
   private:
     QString mExpressionX;
     QString mExpressionY;
     QString mExpressionZ;
     QHash<int, int> mChangingVertexMap;
+    bool mZFromTerrain = false;
 
     QgsTopologicalMesh::Changes apply( QgsMeshEditor *meshEditor ) override;
 

src/ui/mesh/qgsmeshtransformcoordinatesdockwidgetbase.ui

@@ -38,7 +38,14 @@
       </property>
      </widget>
     </item>
-    <item row="4" column="0" colspan="2">
+    <item row="4" column="0">
+     <widget class="QCheckBox" name="mCheckBoxZFromProjectTerrain">
+      <property name="text">
+       <string>Get Z value from project terrain</string>
+      </property>
+     </widget>
+    </item>
+    <item row="5" column="0" colspan="2">
      <layout class="QHBoxLayout" name="horizontalLayout">
       <property name="sizeConstraint">
        <enum>QLayout::SetDefaultConstraint</enum>
@@ -150,16 +157,6 @@
     <item row="1" column="1">
      <widget class="QgsExpressionLineEdit" name="mExpressionEditX" native="true"/>
     </item>
-    <item row="5" column="0" colspan="2">
-     <widget class="QPushButton" name="mGetZValuesButton">
-      <property name="enabled">
-       <bool>false</bool>
-      </property>
-      <property name="text">
-       <string>Get Z value from project terrain</string>
-      </property>
-     </widget>
-    </item>
    </layout>
   </widget>
  </widget>