Fem: Plot vector components in FemPostDataAlongLineFilter - fixes #5916

src/Mod/Fem/App/FemPostFilter.cpp

@@ -152,8 +152,14 @@ FemPostDataAlongLineFilter::FemPostDataAlongLineFilter()
                       App::Prop_None,
                       "Y axis data values used for plotting");
     ADD_PROPERTY_TYPE(PlotData, (""), "DataAlongLine", App::Prop_None, "Field used for plotting");
+    ADD_PROPERTY_TYPE(PlotDataComponent,
+                      ((long)0),
+                      "DataAlongLine",
+                      App::Prop_None,
+                      "Field component used for plotting");
 
     PlotData.setStatus(App::Property::ReadOnly, true);
+    PlotDataComponent.setStatus(App::Property::ReadOnly, true);
     XAxisData.setStatus(App::Property::Output, true);
     YAxisData.setStatus(App::Property::Output, true);
 
@@ -229,6 +235,10 @@ void FemPostDataAlongLineFilter::onChanged(const Property* prop)
     else if (prop == &PlotData) {
         GetAxisData();
     }
+    else if (prop == &PlotDataComponent) {
+        GetAxisData();
+    }
+
     Fem::FemPostFilter::onChanged(prop);
 }
 
@@ -258,9 +268,15 @@ void FemPostDataAlongLineFilter::GetAxisData()
     if (!pdata) {
         return;
     }
-    vtkDataArray* tcoords = dset->GetPointData()->GetTCoords("Texture Coordinates");
 
-    vtkIdType component = 0;
+    // expected "Magnitude" -> 0; "X" -> 1; "Y" -> 2, "Z" -> 3
+    vtkIdType component = PlotDataComponent.getValue();
+    // prevent selecting a component out of range
+    if (!PlotDataComponent.isValid() || component > pdata->GetNumberOfComponents()) {
+        return;
+    }
+
+    vtkDataArray* tcoords = dset->GetPointData()->GetTCoords("Texture Coordinates");
 
     const Base::Vector3d& vec1 = Point1.getValue();
     const Base::Vector3d& vec2 = Point2.getValue();
@@ -268,25 +284,31 @@ void FemPostDataAlongLineFilter::GetAxisData()
     double Len = diff.Length();
 
     for (vtkIdType i = 0; i < dset->GetNumberOfPoints(); ++i) {
-
         double value = 0;
         if (pdata) {
             if (pdata->GetNumberOfComponents() == 1) {
-                value = pdata->GetComponent(i, component);
+                value = pdata->GetComponent(i, 0);
             }
-            else {
-                for (vtkIdType j = 0; j < pdata->GetNumberOfComponents(); ++j) {
-                    value += std::pow(pdata->GetComponent(i, j), 2);
+            else if (pdata->GetNumberOfComponents() > 1) {
+                if (component) {
+                    value = pdata->GetComponent(i, component - 1);
                 }
+                else {
+                    // compute magnitude
+                    for (vtkIdType j = 0; j < pdata->GetNumberOfComponents(); ++j) {
+                        value += std::pow(pdata->GetComponent(i, j), 2);
+                    }
 
-                value = std::sqrt(value);
+                    value = std::sqrt(value);
+                }
             }
         }
 
         values.push_back(value);
-        double tcoord = tcoords->GetComponent(i, component);
+        double tcoord = tcoords->GetComponent(i, 0);
         coords.push_back(tcoord * Len);
     }
+
     YAxisData.setValues(values);
     XAxisData.setValues(coords);
 }

src/Mod/Fem/App/FemPostFilter.h

@@ -99,6 +99,7 @@ public:
     App::PropertyFloatList XAxisData;
     App::PropertyFloatList YAxisData;
     App::PropertyString PlotData;
+    App::PropertyEnumeration PlotDataComponent;
 
     const char* getViewProviderName() const override
     {

src/Mod/Fem/Gui/TaskPostBoxes.cpp

@@ -883,15 +883,30 @@ void TaskPostDataAlongLine::onFieldActivated(int i)
     std::string FieldName = ui->Field->currentText().toStdString();
     static_cast<Fem::FemPostDataAlongLineFilter*>(getObject())->PlotData.setValue(FieldName);
     updateEnumerationList(getTypedView<ViewProviderFemPostObject>()->VectorMode, ui->VectorMode);
+
+    auto vecMode = static_cast<ViewProviderFemPostObject*>(getView())->VectorMode.getEnum();
+    static_cast<Fem::FemPostDataAlongLineFilter*>(getObject())->PlotDataComponent.setValue(vecMode);
 }
 
 void TaskPostDataAlongLine::onVectorModeActivated(int i)
 {
     getTypedView<ViewProviderFemPostObject>()->VectorMode.setValue(i);
+    int comp = ui->VectorMode->currentIndex();
+    static_cast<Fem::FemPostDataAlongLineFilter*>(getObject())->PlotDataComponent.setValue(comp);
 }
 
 std::string TaskPostDataAlongLine::Plot()
 {
+    auto obj = static_cast<Fem::FemPostDataAlongLineFilter*>(getObject());
+    std::string yLabel;
+    // if there is only one component, it is the magnitude
+    if (obj->PlotDataComponent.getEnum().maxValue() < 1) {
+        yLabel = "Magnitude";
+    }
+    else {
+        yLabel = obj->PlotDataComponent.getValueAsString();
+    }
+
     auto xlabel = tr("Length", "X-Axis plot label");
     std::ostringstream oss;
     oss << "import FreeCAD\n\
@@ -903,13 +918,15 @@ plt.figure(title)\n\
 plt.plot(x, y)\n\
 plt.xlabel(\""
         << xlabel.toStdString() << "\")\n\
-plt.ylabel(title)\n\
+plt.ylabel(\""
+        << yLabel << "\")\n\
 plt.title(title)\n\
 plt.grid()\n\
 fig_manager = plt.get_current_fig_manager()\n\
 fig_manager.window.setParent(FreeCADGui.getMainWindow())\n\
 fig_manager.window.setWindowFlag(QtCore.Qt.Tool)\n\
 plt.show()\n";
+
     return oss.str();
 }