Temporary patch to produce empty result in case of any invalidity (spikes, self-intersections, faces inversion).

src/BRepOffset/BRepOffset_MakeOffset.cxx

@@ -1299,9 +1299,11 @@ void BRepOffset_MakeOffset::BuildSplitsOfFaces
     //
     // split the face by the edges
     if (!iCountE) {
+      if (bLimited) {
         aLFImages.Append(aF);
         theImage.Bind(aF, aLFImages);
         aBB.Add(aFaces, aF);
+      }
       continue;
     }
     //
@@ -1404,7 +1406,7 @@ void BRepOffset_MakeOffset::BuildSplitsOfFaces
       //
       UpdateOrigins(theOrigins, aGF);
       //
-      if (aLFImages.Extent() > 1) {
+      if (aLFImages.Extent() >= 1) {
         TopTools_ListOfShape aLFKeep;
         //
         // check offset faces on the coincidence of the 
@@ -2954,12 +2956,34 @@ void BRepOffset_MakeOffset::MakeShells()
         aMV1.Perform();
         bDone = (aMV1.ErrorStatus() == 0);
         if (bDone) {
+          //
+          TopoDS_Shape aResult = aMV1.Shape();
+          //
+          TopTools_IndexedMapOfShape aMFResult;
+          TopExp::MapShapes(aResult, TopAbs_FACE, aMFResult);
+          //
+          // check the result
+          Standard_Boolean bGood = Standard_True;
+          BOPCol_ListIteratorOfListOfShape aItLSF(aLSF);
+          for (; aItLSF.More(); aItLSF.Next()) {
+            const TopoDS_Shape& aFx = aItLSF.Value();
+            if (!aMFResult.Contains(aFx)) {
+              const TopTools_ListOfShape& aLFMx = aMV1.Modified(aFx);
+              if (aLFMx.IsEmpty()) {
+                bGood = Standard_False;
+                break;
+              }
+            }
+          }
+          //
           TopoDS_Compound aShells;
           //
           aBB.MakeCompound(aShells);
           //
-          TopoDS_Shape aResult = aMV1.Shape();
-          //
+          if (!bGood) {
+            myOffsetShape = aShells;
+          }
+          else {
             // collect images of the faces
             TopTools_MapOfShape aMFaces;
             aNb = myFaces.Extent();
@@ -3075,6 +3099,7 @@ void BRepOffset_MakeOffset::MakeShells()
         }
       }
     }
+  }
   //
   if (!bDone) {
     BRepTools_Quilt Glue;
@@ -4126,17 +4151,16 @@ Standard_Boolean CheckBiNormals
    const TopTools_IndexedDataMapOfShapeListOfShape& theOrigins,
    const TopTools_MapOfShape& theMFence,
    Standard_Boolean& bKeep,
-   Standard_Boolean& bRem)
+   Standard_Boolean& bRemove)
 {
   Standard_Boolean bChecked;
+  Standard_Integer aNbEdgesChecked;
   Standard_Real anAngle;
+  TopTools_ListOfShape aLEInv;
   //
-  bKeep = Standard_False;
-  bRem = Standard_True;
-  bChecked = Standard_False;
+  aNbEdgesChecked = 0;
   //
   const TopoDS_Wire& aWIm = BRepTools::OuterWire(aFIm);
-  //
   TopExp_Explorer aExp(aWIm, TopAbs_EDGE);
   for (; aExp.More(); aExp.Next()) {
     const TopoDS_Edge& aEIm = *(TopoDS_Edge*)&aExp.Current();
@@ -4152,7 +4176,6 @@ Standard_Boolean CheckBiNormals
     const TopTools_ListOfShape& aLEOr = theOrigins.FindFromKey(aEIm);
     const TopoDS_Shape& aSOr = aLEOr.First();
     if (aSOr.ShapeType() != TopAbs_EDGE) {
-      bRem = Standard_False;
       continue;
     }
     //
@@ -4180,13 +4203,6 @@ Standard_Boolean CheckBiNormals
       }
     }
     //
-    if (theMFence.Contains(aEIm)) {
-      bChecked = Standard_True;
-      bKeep = Standard_True;
-      bRem = Standard_False;
-      break;
-    }      
-    //
     const TopoDS_Edge& aEOr = *(TopoDS_Edge*)&aLEOr.First();
     //
     TopoDS_Edge aEOrF;
@@ -4206,19 +4222,44 @@ Standard_Boolean CheckBiNormals
       continue;
     }
     //
-    bChecked = Standard_True;
-    // check coincidence of bi-normals
+    ++aNbEdgesChecked;
+    //
     anAngle = aDB1.Angle(aDB2);
     if (Abs(anAngle - M_PI) < Precision::Confusion()) {
-      bRem = bRem && Standard_True;
+      aLEInv.Append(aEIm);
     }
-    else {
-      bRem = Standard_False;
+  }
+  //
+  bChecked = (aNbEdgesChecked > 0);
+  if (!bChecked) {
+    return bChecked;
+  }
+  //
+  // decide whether to remove the split face or not
   bKeep = Standard_True;
+  bRemove = Standard_False;
+  //
+  if (aLEInv.IsEmpty()) {
+    return bChecked;
+  }
+  //
+  TopTools_ListIteratorOfListOfShape aItLS(aLEInv);
+  for (; aItLS.More(); aItLS.Next()) {
+    const TopoDS_Shape& aE = aItLS.Value();
+    if (theMFence.Contains(aE)) {
+      bKeep = Standard_False;
+      bRemove = Standard_True;
       break;
     }
   }
   //
+  if (!bRemove) {
+    if (aNbEdgesChecked == aLEInv.Extent()) {
+      bKeep = Standard_False;
+      bRemove = Standard_True;
+    }
+  }
+  //
   return bChecked;
 }