add option to placement dialog to rotate around center of mass

src/Gui/Placement.cpp

@@ -35,6 +35,7 @@
 #include <Gui/Selection.h>
 #include <Gui/ViewProvider.h>
 #include <App/Document.h>
+#include <App/GeoFeature.h>
 #include <App/PropertyGeo.h>
 #include <Base/Console.h>
 #include <Base/Tools.h>
@@ -263,6 +264,32 @@ void Placement::onPlacementChanged(int)
     /*emit*/ placementChanged(data, incr, false);
 }
 
+void Placement::on_centerOfMass_toggled(bool on)
+{
+    ui->xCnt->setDisabled(on);
+    ui->yCnt->setDisabled(on);
+    ui->zCnt->setDisabled(on);
+
+    if (on) {
+        cntOfMass.Set(0,0,0);
+        std::vector<App::DocumentObject*> sel = Gui::Selection().getObjectsOfType
+            (App::GeoFeature::getClassTypeId());
+        if (!sel.empty()) {
+            for (auto it : sel) {
+                const App::PropertyComplexGeoData* propgeo = static_cast<App::GeoFeature*>(it)->getPropertyOfGeometry();
+                const Data::ComplexGeoData* geodata = propgeo ? propgeo->getComplexData() : nullptr;
+                if (geodata && geodata->getCenterOfGravity(cntOfMass)) {
+                    break;
+                }
+            }
+        }
+
+        ui->xCnt->setValue(cntOfMass.x);
+        ui->yCnt->setValue(cntOfMass.y);
+        ui->zCnt->setValue(cntOfMass.z);
+    }
+}
+
 void Placement::on_applyIncrementalPlacement_toggled(bool on)
 {
     if (on) {
@@ -419,6 +446,15 @@ Base::Placement Placement::getPlacement() const
     return p;
 }
 
+Base::Vector3d Placement::getCenterData() const
+{
+    if (ui->centerOfMass->isChecked())
+        return this->cntOfMass;
+    return Base::Vector3d(ui->xCnt->value().getValue(),
+                          ui->yCnt->value().getValue(),
+                          ui->zCnt->value().getValue());
+}
+
 Base::Placement Placement::getPlacementData() const
 {
     int index = ui->rotationInput->currentIndex();
@@ -427,7 +463,7 @@ Base::Placement Placement::getPlacementData() const
     Base::Vector3d cnt;
 
     pos = Base::Vector3d(ui->xPos->value().getValue(),ui->yPos->value().getValue(),ui->zPos->value().getValue());
-    cnt = Base::Vector3d(ui->xCnt->value().getValue(),ui->yCnt->value().getValue(),ui->zCnt->value().getValue());
+    cnt = getCenterData();
 
     if (index == 0) {
         Base::Vector3d dir = getDirection();
@@ -448,6 +484,7 @@ QString Placement::getPlacementString() const
 {
     QString cmd;
     int index = ui->rotationInput->currentIndex();
+    Base::Vector3d cnt = getCenterData();
 
     if (index == 0) {
         Base::Vector3d dir = getDirection();
@@ -460,9 +497,9 @@ QString Placement::getPlacementString() const
             .arg(dir.y)
             .arg(dir.z)
             .arg(ui->angle->value().getValue())
-            .arg(ui->xCnt->value().getValue())
-            .arg(ui->yCnt->value().getValue())
-            .arg(ui->zCnt->value().getValue());
+            .arg(cnt.x)
+            .arg(cnt.y)
+            .arg(cnt.z);
     }
     else if (index == 1) {
         cmd = QString::fromLatin1(
@@ -473,9 +510,9 @@ QString Placement::getPlacementString() const
             .arg(ui->yawAngle->value().getValue())
             .arg(ui->pitchAngle->value().getValue())
             .arg(ui->rollAngle->value().getValue())
-            .arg(ui->xCnt->value().getValue())
-            .arg(ui->yCnt->value().getValue())
-            .arg(ui->zCnt->value().getValue());
+            .arg(cnt.x)
+            .arg(cnt.y)
+            .arg(cnt.z);
     }
 
     return cmd;

src/Gui/Placement.h

@@ -63,11 +63,13 @@ private Q_SLOTS:
     void on_applyIncrementalPlacement_toggled(bool);
     void onPlacementChanged(int);
     void on_resetButton_clicked();
+    void on_centerOfMass_toggled(bool);
 
 private:
     bool onApply();
     void setPlacementData(const Base::Placement&);
     Base::Placement getPlacementData() const;
+    Base::Vector3d getCenterData() const;
     QString getPlacementString() const;
     void directionActivated(int);
     void applyPlacement(const Base::Placement& p, bool incremental);
@@ -87,6 +89,7 @@ private:
     QSignalMapper* signalMapper;
     Connection connectAct;
     Base::Placement ref;
+    Base::Vector3d cntOfMass;
     std::string propertyName; // the name of the placement property
     std::set<std::string> documents;
 

src/Gui/Placement.ui

@@ -108,7 +108,7 @@
       <property name="spacing">
        <number>6</number>
       </property>
-      <item row="3" column="1">
+      <item row="4" column="1">
        <spacer>
         <property name="orientation">
          <enum>Qt::Vertical</enum>
@@ -169,6 +169,13 @@
       <item row="2" column="1">
        <widget class="Gui::QuantitySpinBox" name="zCnt"/>
       </item>
+      <item row="3" column="0" colspan="2">
+       <widget class="QCheckBox" name="centerOfMass">
+        <property name="text">
+         <string>Use center of mass</string>
+        </property>
+       </widget>
+      </item>
      </layout>
     </widget>
    </item>