Create Base property for SketchBased features and changed Pad to use it

src/Mod/PartDesign/App/Body.cpp

@@ -86,6 +86,22 @@ const Part::TopoShape Body::getPreviousSolid(const PartDesign::Feature* f)
     return static_cast<const PartDesign::Feature*>(*it)->Shape.getShape();
 }
 
+App::DocumentObject* Body::getTipSolidFeature()
+{
+    std::vector<App::DocumentObject*> features = Model.getValues();
+    if (features.empty()) return NULL;
+    std::vector<App::DocumentObject*>::const_iterator it = std::find(features.begin(), features.end(), Tip.getValue());
+
+    // Skip sketches
+    while (!(*it)->getTypeId().isDerivedFrom(PartDesign::Feature::getClassTypeId())) {
+        if (it == features.begin())
+            return NULL;
+        it--;
+    }
+
+    return *it;
+}
+
 const bool Body::hasFeature(const App::DocumentObject* f)
 {
     std::vector<App::DocumentObject*> features = Model.getValues();

src/Mod/PartDesign/App/Body.h

@@ -58,6 +58,14 @@ public:
     /// Get the tip shape
     const Part::TopoShape getTipShape();
 
+    /**
+      * Return Tip feature if it is a solid. Otherwise, go backwards in the Model and
+      * find the first feature that is a solid (i.e. Sketches are skipped)
+      * This is used by SketchBased features to determine the shape they should fuse with or cut out off
+      * NOTE: Currently only PartDesign features are accepted as TipSolidFeatures
+      */
+    App::DocumentObject *getTipSolidFeature();
+
     /// Return the shape of the feature preceding this feature
     const Part::TopoShape getPreviousSolid(const PartDesign::Feature* f);
 

src/Mod/PartDesign/App/FeaturePad.cpp

@@ -96,7 +96,20 @@ App::DocumentObjectExecReturn *Pad::execute(void)
         return new App::DocumentObjectExecReturn(e.what());
     }
 
+    TopoDS_Shape support;
+    try {
+        support = getSupportShape();
+    } catch (const Base::Exception&) {
+        // ignore, because support isn't mandatory
+        support = TopoDS_Shape();
+    }
+
+/*
     // Find Body feature which owns this Pad and get the shape of the feature preceding this one for fusing
+    // This method was rejected in favour of the Base property because it makes the feature atomic (independent of the
+    // Body object). See
+    // https://sourceforge.net/apps/phpbb/free-cad/viewtopic.php?f=19&t=3831
+    // https://sourceforge.net/apps/phpbb/free-cad/viewtopic.php?f=19&t=3855
     PartDesign::Body* body = getBody();
     if (body == NULL) {
         return new App::DocumentObjectExecReturn(
@@ -113,6 +126,7 @@ App::DocumentObjectExecReturn *Pad::execute(void)
         support = TopoDS_Shape();
     else
         support = prevShape._Shape;
+*/
 
     // get the Sketch plane
     Base::Placement SketchPos = sketch->Placement.getValue();
@@ -184,13 +198,22 @@ App::DocumentObjectExecReturn *Pad::execute(void)
         prism = refineShapeIfActive(prism);
         this->AddShape.setValue(prism);
 
-        // if the sketch has a support fuse them to get one result object
-        if (!support.IsNull()) {
+        // if the Base property has a valid shape, fuse the prism into it
+        TopoDS_Shape base;
+        try {
+            base = getBaseShape();
+            base.Move(invObjLoc);
+        } catch (const Base::Exception&) {
+            // fall back to support (for legacy features)
+            base = support;
+        }
+
+        if (!base.IsNull()) {
             // Let's call algorithm computing a fuse operation:
-            BRepAlgoAPI_Fuse mkFuse(support, prism);
+            BRepAlgoAPI_Fuse mkFuse(base, prism);
             // Let's check if the fusion has been successful
             if (!mkFuse.IsDone())
-                return new App::DocumentObjectExecReturn("Pad: Fusion with support failed");
+                return new App::DocumentObjectExecReturn("Pad: Fusion with base feature failed");
             TopoDS_Shape result = mkFuse.Shape();
             // we have to get the solids (fuse sometimes creates compounds)
             TopoDS_Shape solRes = this->getSolid(result);

src/Mod/PartDesign/App/FeatureSketchBased.cpp

@@ -98,6 +98,7 @@ PROPERTY_SOURCE(PartDesign::SketchBased, PartDesign::Feature)
 
 SketchBased::SketchBased()
 {
+    ADD_PROPERTY(Base,(0));
     ADD_PROPERTY_TYPE(Sketch,(0),"SketchBased", App::Prop_None, "Reference to sketch");
     ADD_PROPERTY_TYPE(Midplane,(0),"SketchBased", App::Prop_None, "Extrude symmetric to sketch face");
     ADD_PROPERTY_TYPE(Reversed, (0),"SketchBased", App::Prop_None, "Reverse extrusion direction");
@@ -231,6 +232,26 @@ const TopoDS_Shape& SketchBased::getSupportShape() const {
     return result;
 }
 
+const TopoDS_Shape& SketchBased::getBaseShape() const {
+    App::DocumentObject* BaseLink = Base.getValue();
+    if (BaseLink == NULL) throw Base::Exception("Base property not set");
+    Part::Feature* BaseObject = NULL;
+    if (BaseLink->getTypeId().isDerivedFrom(Part::Feature::getClassTypeId()))
+        BaseObject = static_cast<Part::Feature*>(BaseLink);
+
+    if (BaseObject == NULL)
+        throw Base::Exception("No base feature linked");
+
+    const TopoDS_Shape& result = BaseObject->Shape.getValue();
+    if (result.IsNull())
+        throw Base::Exception("Base feature's shape is invalid");
+    TopExp_Explorer xp (result, TopAbs_SOLID);
+    if (!xp.More())
+        throw Base::Exception("Base feature's shape is not a solid");
+
+    return result;
+}
+
 int SketchBased::getSketchAxisCount(void) const
 {
     Part::Part2DObject *sketch = static_cast<Part::Part2DObject*>(Sketch.getValue());

src/Mod/PartDesign/App/FeatureSketchBased.h

@@ -44,7 +44,10 @@ class PartDesignExport SketchBased : public PartDesign::Feature
 public:
     SketchBased();
 
-    /// Common properties for all sketch based features
+    // Common properties for all sketch based features
+    /// Base feature which this feature will be fused into or cut out of
+    App::PropertyLink   Base;
+    /// Sketch used to create this feature
     App::PropertyLink   Sketch;
     /// Reverse extrusion direction
     App::PropertyBool       Reversed;
@@ -72,6 +75,8 @@ public:
     Part::Feature* getSupport() const;
     /// Returns the sketch support shape (if any)
     const TopoDS_Shape& getSupportShape() const;
+    /// Returns the base property's shape (if any)
+    const TopoDS_Shape& getBaseShape() const;
 
     /// retrieves the number of axes in the linked sketch (defined as construction lines)
     int getSketchAxisCount(void) const;