[FEM] fix a variable casting

- reported by MSVC not to cast a float to a double but as double directly

- also remove some superfluous Boolean comparisons

src/Mod/Fem/App/FemMesh.cpp

@@ -1085,7 +1085,7 @@ std::set<int> FemMesh::getEdgesOnly(void) const
                 break;
             }
         }
-        if (edgeBelongsToAFace == false)
+        if (!edgeBelongsToAFace)
             resultIDs.insert(aEdge->GetID());
     }
 
@@ -1144,7 +1144,7 @@ std::set<int> FemMesh::getFacesOnly(void) const
                 break;
             }
         }
-        if (faceBelongsToAVolume == false)
+        if (!faceBelongsToAVolume)
             resultIDs.insert(aFace->GetID());
     }
 
@@ -2172,7 +2172,7 @@ void FemMesh::writeABAQUS(const std::string &Filename, int elemParam, bool group
                         anABAQUS_Output  << ", " << *kt;
                     }
                     else {
-                        if (first_line == true) {
+                        if (first_line) {
                             anABAQUS_Output << "," << std::endl;
                             first_line = false;
                         }
@@ -2232,7 +2232,7 @@ void FemMesh::writeABAQUS(const std::string &Filename, int elemParam, bool group
     anABAQUS_Output << elsetname << std::endl;
 
     // groups
-    if (groupParam == false) {
+    if (!groupParam) {
         anABAQUS_Output.close();
     }
     else {

src/Mod/Fem/Gui/Command.cpp

@@ -985,7 +985,7 @@ void DefineNodesCallback(void* ud, SoEventCallback* n)
         const SMDS_MeshNode* aNode = aNodeIter->next();
         Base::Vector3f vec(aNode->X(), aNode->Y(), aNode->Z());
         pt2d = proj(vec);
-        if (polygon.Contains(Base::Vector2d(pt2d.x, pt2d.y)) == true)
+        if (polygon.Contains(Base::Vector2d(pt2d.x, pt2d.y)))
             IntSet.insert(aNode->GetID());
     }
 

src/Mod/Fem/Gui/ViewProviderFemPostObject.cpp

@@ -449,8 +449,8 @@ void ViewProviderFemPostObject::setRangeOfColorBar(double min, double max)
 {
     try {
         if (min >= max) {
-            min = max - 10 * std::numeric_limits<float>::epsilon();
-            max = max + 10 * std::numeric_limits<float>::epsilon();
+            min = max - 10 * std::numeric_limits<double>::epsilon();
+            max = max + 10 * std::numeric_limits<double>::epsilon();
         }
         m_colorBar->setRange(min, max);
     }
@@ -465,7 +465,6 @@ void ViewProviderFemPostObject::WriteColorData(bool ResetColorBarRange) {
         return;
 
     if (Field.getEnumVector().empty() || Field.getValue() == 0) {
-
         m_material->diffuseColor.setValue(SbColor(0.8, 0.8, 0.8));
         m_material->transparency.setValue(0.);
         m_materialBinding->value = SoMaterialBinding::OVERALL;
@@ -473,7 +472,6 @@ void ViewProviderFemPostObject::WriteColorData(bool ResetColorBarRange) {
         return;
     };
 
-
     int array = Field.getValue() - 1; //0 is none
     vtkPolyData* pd = m_currentAlgorithm->GetOutput();
     vtkDataArray* data = pd->GetPointData()->GetArray(array);
@@ -483,7 +481,7 @@ void ViewProviderFemPostObject::WriteColorData(bool ResetColorBarRange) {
         component = 0;
 
     //build the lookuptable
-    if (ResetColorBarRange == true) {
+    if (ResetColorBarRange) {
         double range[2];
         data->GetRange(range, component);
         setRangeOfColorBar(range[0], range[1]);
@@ -591,7 +589,7 @@ bool ViewProviderFemPostObject::doubleClicked(void) {
     // check if backlight is enabled
     ParameterGrp::handle hGrp = App::GetApplication().GetParameterGroupByPath("User parameter:BaseApp/Preferences/View");
     bool isBackLightEnabled = hGrp->GetBool("EnableBacklight", false);
-    if (isBackLightEnabled == false)
+    if (!isBackLightEnabled)
         Base::Console().Error("Backlight is not enabled. Due to a VTK implementation problem you really should consider to enable backlight in FreeCAD display preferences if you work with VTK post processing.\n");
     // set edit
     Gui::Application::Instance->activeDocument()->setEdit(this, (int)ViewProvider::Default);