PartDesign: Add method suggesting Revolution Reversed property so that material is always added to the support

src/Mod/PartDesign/App/FeatureRevolution.cpp

@@ -34,6 +34,8 @@
 # include <BRepAlgoAPI_Fuse.hxx>
 # include <Precision.hxx>
 # include <gp_Lin.hxx>
+# include <GProp_GProps.hxx>
+# include <BRepGProp.hxx>
 #endif
 
 #include <Base/Axis.h>
@@ -75,9 +77,9 @@ App::DocumentObjectExecReturn *Revolution::execute(void)
     // Validate parameters
     double angle = Angle.getValue();
     if (angle < Precision::Confusion())
-        return new App::DocumentObjectExecReturn("Angle of groove too small");
+        return new App::DocumentObjectExecReturn("Angle of revolution too small");
     if (angle > 360.0)
-        return new App::DocumentObjectExecReturn("Angle of groove too large");
+        return new App::DocumentObjectExecReturn("Angle of revolution too large");
 
     angle = Base::toRadians<double>(angle);
     // Reverse angle if selected
@@ -205,4 +207,40 @@ App::DocumentObjectExecReturn *Revolution::execute(void)
     }
 }
 
+bool Revolution::suggestReversed(void) const
+{
+    // suggest a value for Reversed flag so that material is added to the support
+    try {
+        Part::Part2DObject* sketch = getVerifiedSketch();
+        std::vector<TopoDS_Wire> wires = getSketchWires();
+        TopoDS_Shape sketchshape = makeFace(wires);
+
+        Base::Vector3f b = Base.getValue();
+        Base::Vector3f v = Axis.getValue();
+
+        // get centre of gravity of the sketch face
+        GProp_GProps props;
+        BRepGProp::SurfaceProperties(sketchshape, props);
+        gp_Pnt cog = props.CentreOfMass();
+        Base::Vector3f p_cog(cog.X(), cog.Y(), cog.Z());
+        // get direction to cog from its projection on the revolve axis
+        Base::Vector3f perp_dir = p_cog - p_cog.Perpendicular(b, v);
+        // get cross product of projection direction with revolve axis direction
+        Base::Vector3f cross = v % perp_dir;
+        // get sketch vector pointing away from support material
+        Base::Placement SketchPos = sketch->Placement.getValue();
+        Base::Rotation SketchOrientation = SketchPos.getRotation();
+        Base::Vector3d SketchNormal(0,0,1);
+        SketchOrientation.multVec(SketchNormal,SketchNormal);
+        // simply convert double to float
+        Base::Vector3f norm(SketchNormal.x, SketchNormal.y, SketchNormal.z);
+
+        // return true if the angle between norm and cross is acute
+        return norm * cross < 0.f;
+    }
+    catch (...) {
+        return false;
+    }
+}
+
 }

src/Mod/PartDesign/App/FeatureRevolution.h

@@ -62,6 +62,8 @@ public:
         return "PartDesignGui::ViewProviderRevolution";
     }
     //@}
+
+    bool suggestReversed(void) const;
 };
 
 } //namespace PartDesign