0032701: Modeling Algorithms - 2d curve has bending near the degenerated edge of the face

ApproxInt_Approx, ApproxInt_KnotTools, BRepApprox_Approx,
GeomInt_IntSS, IntTools_FaceFace:
  Analysis of curvature is added for adjusting ParametrizationType

IntPatch_Intersection.cxx - adding methods for estimation of UV max step depending on used surfaces

GeomInt_IntSS.cxx, IntTools_FaceFace.cxx - using methods for max step estimation

Approx_SameParameter.cxx - adding control against big values.

BOPAlgo_PaveFiller_6.cxx - adjusting position of faces before intersection

src/BOPAlgo/BOPAlgo_PaveFiller_6.cxx

@@ -278,6 +278,35 @@ void BOPAlgo_PaveFiller::PerformFF(const Message_ProgressRange& theRange)
   // Post-processing options
   Standard_Boolean bSplitCurve = Standard_False;
   //
+  // Collect all pairs of Edge/Edge interferences to check if
+  // some faces have to be moved to obtain more precise intersection
+  NCollection_DataMap<BOPDS_Pair, TColStd_ListOfInteger, BOPDS_PairMapHasher> aEEMap;
+  const BOPDS_VectorOfInterfEE& aVEEs = myDS->InterfEE();
+  for (Standard_Integer iEE = 0; iEE < aVEEs.Size(); ++iEE)
+  {
+    const BOPDS_Interf& aEE = aVEEs(iEE);
+    if (!aEE.HasIndexNew())
+    {
+      continue;
+    }
+    Standard_Integer nE1, nE2;
+    aEE.Indices(nE1, nE2);
+
+    const Standard_Integer nVN = aEE.IndexNew();
+
+    BOPDS_Pair aPair(nE1, nE2);
+    TColStd_ListOfInteger* pPoints = aEEMap.ChangeSeek(aPair);
+    if (pPoints)
+    {
+      pPoints->Append(nVN);
+    }
+    else
+    {
+      pPoints = aEEMap.Bound(BOPDS_Pair(nE1, nE2), TColStd_ListOfInteger());
+      pPoints->Append(nVN);
+    }
+  }
+
   // Prepare the pairs of faces for intersection
   BOPAlgo_VectorOfFaceFace aVFaceFace;
   myIterator->Initialize(TopAbs_FACE, TopAbs_FACE);
@@ -306,15 +335,87 @@ void BOPAlgo_PaveFiller::PerformFF(const Message_ProgressRange& theRange)
           continue;
         }
       }
+
+      // Check if there is an intersection between edges of the faces. 
+      // If there is an intersection, check if there is a shift between the edges
+      // (intersection point is on some distance from the edges), and move one of 
+      // the faces to the point of exact edges intersection. This should allow 
+      // obtaining more precise intersection curves between the faces 
+      // (at least the curves should reach the boundary). 
+      // Note, that currently this check considers only closed edges (seam edges).
+      TopoDS_Face aFShifted1 = aF1, aFShifted2 = aF2;
+      // Keep shift value to use it as the tolerance for intersection curves
+      Standard_Real aShiftValue = 0.;
+
+      if (aBAS1.GetType() != GeomAbs_Plane ||
+        aBAS2.GetType() != GeomAbs_Plane) {
+
+        Standard_Boolean isFound = Standard_False;
+        for (TopExp_Explorer aExp1(aF1, TopAbs_EDGE); !isFound && aExp1.More(); aExp1.Next())
+        {
+          const TopoDS_Edge& aE1 = TopoDS::Edge(aExp1.Current());
+          const Standard_Integer nE1 = myDS->Index(aE1);
+
+          for (TopExp_Explorer aExp2(aF2, TopAbs_EDGE); !isFound && aExp2.More(); aExp2.Next())
+          {
+            const TopoDS_Edge& aE2 = TopoDS::Edge(aExp2.Current());
+            const Standard_Integer nE2 = myDS->Index(aE2);
+
+            Standard_Boolean bIsClosed1 = BRep_Tool::IsClosed(aE1, aF1);
+            Standard_Boolean bIsClosed2 = BRep_Tool::IsClosed(aE2, aF2);
+            if (!bIsClosed1 && !bIsClosed2)
+            {
+              continue;
+            }
+
+            const TColStd_ListOfInteger* pPoints = aEEMap.Seek(BOPDS_Pair(nE1, nE2));
+            if (!pPoints)
+            {
+              continue;
+            }
+
+            for (TColStd_ListOfInteger::Iterator itEEP(*pPoints); itEEP.More(); itEEP.Next())
+            {
+              const Standard_Integer& nVN = itEEP.Value();
+              const TopoDS_Vertex& aVN = TopoDS::Vertex(myDS->Shape(nVN));
+              const gp_Pnt& aPnt = BRep_Tool::Pnt(aVN);
+
+              // Compute points exactly on the edges 
+              GeomAPI_ProjectPointOnCurve& aProjPC1 = myContext->ProjPC(aE1);
+              GeomAPI_ProjectPointOnCurve& aProjPC2 = myContext->ProjPC(aE2);
+              aProjPC1.Perform(aPnt);
+              aProjPC2.Perform(aPnt);
+              if (!aProjPC1.NbPoints() && !aProjPC2.NbPoints())
+              {
+                continue;
+              }
+              gp_Pnt aP1 = aProjPC1.NbPoints() > 0 ? aProjPC1.NearestPoint() : aPnt;
+              gp_Pnt aP2 = aProjPC2.NbPoints() > 0 ? aProjPC2.NearestPoint() : aPnt;
+
+              Standard_Real aShiftDist = aP1.Distance(aP2);
+              if (aShiftDist > BRep_Tool::Tolerance(aVN))
+              {
+                // Move one of the faces to the point of exact intersection of edges
+                gp_Trsf aTrsf;
+                aTrsf.SetTranslation(bIsClosed1 ? gp_Vec(aP1, aP2) : gp_Vec(aP2, aP1));
+                TopLoc_Location aLoc(aTrsf);
+                (bIsClosed1 ? &aFShifted1 : &aFShifted2)->Move(aLoc);
+                aShiftValue = aShiftDist;
+                isFound = Standard_True;
+              }
+            }
+          }
+        }
+      }
       //
       BOPAlgo_FaceFace& aFaceFace=aVFaceFace.Appended();
       //
       aFaceFace.SetRunParallel (myRunParallel);
       aFaceFace.SetIndices(nF1, nF2);
-      aFaceFace.SetFaces(aF1, aF2);
+      aFaceFace.SetFaces(aFShifted1, aFShifted2);
       aFaceFace.SetBoxes (myDS->ShapeInfo (nF1).Box(), myDS->ShapeInfo (nF2).Box());
-      // compute minimal tolerance for the curves
-      Standard_Real aTolFF = ToleranceFF(aBAS1, aBAS2);
+      // Note: in case of faces with closed edges it should not be less than value of the shift
+      Standard_Real aTolFF = Max(aShiftValue, ToleranceFF(aBAS1, aBAS2));
       aFaceFace.SetTolFF(aTolFF);
       //
       IntSurf_ListOfPntOn2S aListOfPnts;