Part: Fix orientation of internal shells of a solid (#26717)

* Part: Fix orientation of internal shells of a solid

If a solid consists of multiple shells then it can happen that the
internal shells have incorrect orientation that leads to a broken solid.

This fixes issue https://github.com/FreeCAD/FreeCAD/issues/24994

* Part: Add method Feature::fixSolids

This method explicitly checks for solids with the error
'BRepCheck_EnclosedRegion' that means that internal shells of a solid
are wrong.

Using ShapeFix_Solid fixes the solid.

---------

Co-authored-by: wwmayer <wmayer@freecad.org>

src/Mod/Part/App/OpenCascadeAll.h

@@ -150,6 +150,7 @@
 #include <BRepCheck_Analyzer.hxx>
 #include <BRepCheck_ListIteratorOfListOfStatus.hxx>
 #include <BRepCheck_Result.hxx>
+#include <BRepCheck_Solid.hxx>
 #include <BRepClass_FaceClassifier.hxx>
 #include <BRepClass3d.hxx>
 #include <BRepClass3d_SolidClassifier.hxx>

src/Mod/Part/App/modelRefine.cpp

@@ -1292,6 +1292,13 @@ bool FaceUniter::process()
     return true;
 }
 
+void FaceUniter::fixOrientation(const TopoDS_Shell& shell)
+{
+    if (shell.Orientation() != workShell.Orientation()) {
+        workShell.Reverse();
+    }
+}
+
 /////////////////////////////////////////////////////////////////////////////////////////////////////////
 
 // BRepBuilderAPI_RefineModel implement a way to log all modifications on the faces
@@ -1358,11 +1365,16 @@ void Part::BRepBuilderAPI_RefineModel::Build()
             const TopoDS_Solid& solid = TopoDS::Solid(xp.Current());
             BRepTools_ReShape reshape;
             TopExp_Explorer it;
+            int countShells = 0;
             for (it.Init(solid, TopAbs_SHELL); it.More(); it.Next()) {
+                countShells++;
                 const TopoDS_Shell& currentShell = TopoDS::Shell(it.Current());
                 ModelRefine::FaceUniter uniter(currentShell);
                 if (uniter.process()) {
                     if (uniter.isModified()) {
+                        if (countShells > 1) {
+                            uniter.fixOrientation(currentShell);
+                        }
                         const TopoDS_Shell& newShell = uniter.getShell();
                         reshape.Replace(currentShell, newShell);
                         LogModifications(uniter);

src/Mod/Part/App/modelRefine.h

@@ -198,6 +198,7 @@ public:
     {
         return workShell;
     }
+    void fixOrientation(const TopoDS_Shell& shell);
     bool isModified()
     {
         return modifiedSignal;

src/Mod/PartDesign/App/Feature.cpp

@@ -23,11 +23,15 @@
 
 #include <BRep_Tool.hxx>
 #include <BRepBuilderAPI_MakeFace.hxx>
+#include <BRepCheck_Solid.hxx>
+#include <BRepCheck_Status.hxx>
 #include <gp_Pln.hxx>
 #include <gp_Pnt.hxx>
+#include <ShapeFix_Solid.hxx>
 #include <Standard_Failure.hxx>
 #include <TopExp_Explorer.hxx>
 #include <TopoDS.hxx>
+#include <TopoDS_Builder.hxx>
 
 
 #include "App/Datums.h"
@@ -241,6 +245,44 @@ int Feature::countSolids(const TopoDS_Shape& shape, TopAbs_ShapeEnum type)
     return result;
 }
 
+TopoShape Feature::fixSolids(const TopoShape& solids)
+{
+    if (solids.isNull()) {
+        return solids;
+    }
+
+    std::vector<TopoDS_Solid> fixSolids;
+
+    TopExp_Explorer xp;
+    xp.Init(solids.getShape(), TopAbs_SOLID);
+    for (; xp.More(); xp.Next()) {
+        TopoDS_Solid solid = TopoDS::Solid(xp.Current());
+        BRepCheck_Solid bs(solid);
+        if (bs.IsStatusOnShape(solid)) {
+            const auto& listOfStatus = bs.StatusOnShape(solid);
+            if (listOfStatus.Contains(BRepCheck_EnclosedRegion)) {
+                fixSolids.emplace_back(solid);
+            }
+        }
+    }
+
+    if (fixSolids.empty()) {
+        return solids;
+    }
+
+    TopoDS_Compound comp;
+    TopoDS_Builder bb;
+    bb.MakeCompound(comp);
+    for (const TopoDS_Solid& it : fixSolids) {
+        ShapeFix_Solid fix(it);
+        fix.Perform();
+        bb.Add(comp, fix.Solid());
+    }
+
+    TopoShape fixShape(comp);
+    return fixShape;
+}
+
 bool Feature::isSingleSolidRuleSatisfied(const TopoDS_Shape& shape, TopAbs_ShapeEnum type)
 {
     if (singleSolidRuleMode() == Feature::SingleSolidRuleMode::Disabled) {

src/Mod/PartDesign/App/Feature.h

@@ -127,6 +127,11 @@ protected:
     TopoShape getSolid(const TopoShape&) const;
     static int countSolids(const TopoDS_Shape&, TopAbs_ShapeEnum type = TopAbs_SOLID);
 
+    /**
+     * Fix solids
+     */
+    TopoShape fixSolids(const TopoShape&);
+
     /**
      * Checks if the single-solid body rule is fulfilled.
      */