0027896: Prm-Prm intersection algo returns wrong result if it is called with start intersection point, which lies in the domain boundary

Purger has been disabled (in IntPatch_PrmPrmIntersection algorithm) if some points have been added in the Walking line (it is stupidly, first, to insert some points in the line and, after that, to delete points from this line).

Some improvements in IntWalk_PWalking::SeekPointOnBoundary(...) method have been made (see comments in the code for detail information).

Some test cases have been adjusted according to their new behavior.

src/Draft/Draft_Modification_1.cxx

@@ -1574,10 +1574,22 @@ void Draft_Modification::Perform ()
         anIntCurv->D1(aParF, aPf, aDirNF);
         anIntCurv->D1(aParL, aPl, aDirNL);
 
-        aDirNF.Normalize();
+        Standard_Real aSqMagn = aDirNF.SquareMagnitude();
-        aDirNL.Normalize();
+
-        aDirOF.Normalize();
+        if (aSqMagn > Precision::SquareConfusion())
-        aDirOL.Normalize();
+          aDirNF.Divide(sqrt(aSqMagn));
+
+        aSqMagn = aDirNL.SquareMagnitude();
+        if (aSqMagn > Precision::SquareConfusion())
+          aDirNL.Divide(sqrt(aSqMagn));
+
+        aSqMagn = aDirOF.SquareMagnitude();
+        if (aSqMagn > Precision::SquareConfusion())
+          aDirOF.Divide(sqrt(aSqMagn));
+
+        aSqMagn = aDirOL.SquareMagnitude();
+        if (aSqMagn > Precision::SquareConfusion())
+          aDirOL.Divide(sqrt(aSqMagn));
 
         const Standard_Real aCosF = aDirNF.Dot(aDirOF), aCosL = aDirNL.Dot(aDirOL);
         const Standard_Real aCosMax = Abs(aCosF) > Abs(aCosL) ? aCosF : aCosL;

src/IntPatch/IntPatch_ImpPrmIntersection.cxx

@@ -1404,13 +1404,28 @@ void IntPatch_ImpPrmIntersection::Perform (const Handle(Adaptor3d_HSurface)& Sur
 
   for (Standard_Integer i=1, aNbLin = slin.Length(); i<=aNbLin; i++)
   {
-    Handle(IntPatch_Line)& aL = slin(i);
+    Handle(IntPatch_PointLine) aL = Handle(IntPatch_PointLine)::DownCast(slin(i));
     
     if (!reversed)
       IntPatch_RstInt::PutVertexOnLine(aL,Surf1,D1,Surf2,Standard_True,TolTang);
     else
       IntPatch_RstInt::PutVertexOnLine(aL,Surf2,D2,Surf1,Standard_False,TolTang);
 
+    if (aL->NbPnts() <= 2)
+    {
+      Standard_Boolean aCond = aL->NbPnts() < 2;
+      if (!aCond)
+        aCond = (aL->Point(1).IsSame(aL->Point(2), Precision::Confusion()));
+
+      if (aCond)
+      {
+        slin.Remove(i);
+        i--;
+        aNbLin--;
+        continue;
+      }
+    }
+
     if(aL->ArcType() == IntPatch_Walking)
     {
       const Handle(IntPatch_WLine) aWL = Handle(IntPatch_WLine)::DownCast(aL);

src/IntPatch/IntPatch_PrmPrmIntersection.cxx

@@ -2331,27 +2331,26 @@ void IntPatch_PrmPrmIntersection::Perform (const Handle(Adaptor3d_HSurface)& Sur
 
                 //
                 Standard_Boolean bPWIsDone;
-                Standard_Integer iPWNbPoints, aNbPointsVer;
                 Standard_Real aD11, aD12, aD21, aD22, aDx;
                 //
                 bPWIsDone=PW.IsDone();
 
                 if(bPWIsDone)
                 {
-                  iPWNbPoints=PW.NbPoints();
+                  Standard_Boolean hasBeenAdded = Standard_False;
-                  //
+                  if(PW.NbPoints() > 2 )
-                  if( iPWNbPoints > 2 )
                   {
-                    //Try to extend the intersection line to boundary, if it is possibly
+                    //Try to extend the intersection line to the boundary,
+                    //if it is possibly
                     PW.PutToBoundary(Surf1, Surf2);
 
                     const Standard_Integer aMinNbPoints = 40;
-                    if(iPWNbPoints < aMinNbPoints)
+                    if(PW.NbPoints() < aMinNbPoints)
                     {
-                      PW.SeekAdditionalPoints(Surf1, Surf2, aMinNbPoints);
+                      hasBeenAdded = PW.SeekAdditionalPoints(Surf1, Surf2, aMinNbPoints);
-                      iPWNbPoints = PW.NbPoints();
                     }
                     
+                    Standard_Integer iPWNbPoints = PW.NbPoints(), aNbPointsVer = 0;
                     RejectLine = Standard_False;
                     Point3dDebut = PW.Value(1).Value();
                     Point3dFin = PW.Value(iPWNbPoints).Value();
@@ -2450,6 +2449,7 @@ void IntPatch_PrmPrmIntersection::Perform (const Handle(Adaptor3d_HSurface)& Sur
 
                       Standard_Real TolTang = TolTangency;
                       Handle(IntPatch_WLine) wline = new IntPatch_WLine(PW.Line(),Standard_False,trans1,trans2);
+                      wline->EnablePurging(!hasBeenAdded);
                       IntPatch_RstInt::PutVertexOnLine(wline,Surf1,D1,Surf2,Standard_True,TolTang);
                       IntPatch_RstInt::PutVertexOnLine(wline,Surf2,D2,Surf1,Standard_False,TolTang);
                       if(wline->NbVertex() == 0)
@@ -2583,12 +2583,13 @@ void IntPatch_PrmPrmIntersection::Perform (const Handle(Adaptor3d_HSurface)& Sur
 
           if(PW.IsDone())
           {
+            Standard_Boolean hasBeenAdded = Standard_False;
             if(PW.NbPoints()>2)
             { 
               const Standard_Integer aMinNbPoints = 40;
               if(PW.NbPoints() < aMinNbPoints)
               {
-                PW.SeekAdditionalPoints(Surf1, Surf2, aMinNbPoints);
+                hasBeenAdded = PW.SeekAdditionalPoints(Surf1, Surf2, aMinNbPoints);
               }
 
               //-----------------------------------------------
@@ -2657,6 +2658,7 @@ void IntPatch_PrmPrmIntersection::Perform (const Handle(Adaptor3d_HSurface)& Sur
 
                 Standard_Real TolTang = TolTangency;
                 Handle(IntPatch_WLine) wline = new IntPatch_WLine(PW.Line(),Standard_False,trans1,trans2);
+                wline->EnablePurging(!hasBeenAdded);
                 IntPatch_RstInt::PutVertexOnLine(wline,Surf1,D1,Surf2,Standard_True,TolTang);
                 IntPatch_RstInt::PutVertexOnLine(wline,Surf2,D2,Surf1,Standard_False,TolTang);
 

src/IntPatch/IntPatch_WLine.cxx

@@ -479,7 +479,7 @@ void IntPatch_WLine::ComputeVertexParameters( const Standard_Real RTol)
   //-- On detecte les points confondus dans la LineOn2S
   Standard_Real dmini = Precision::Confusion();
   dmini*=dmini;
-  for(i=2; i<=nbponline; i++) { 
+  for(i=2; (i<=nbponline) && (nbponline > 2); i++) { 
     const IntSurf_PntOn2S& aPnt1=curv->Value(i-1);
     const IntSurf_PntOn2S& aPnt2=curv->Value(i);
     Standard_Real d = (aPnt1.Value()).SquareDistance((aPnt2.Value()));

src/IntWalk/IntWalk_PWalking.cxx

@@ -2298,25 +2298,131 @@ SeekPointOnBoundary(const Handle(Adaptor3d_HSurface)& theASurf1,
   if (aSingularStatus)
     aPnt = aSingularPnt;
 
-  if(aStatus || aSingularStatus)
+  if (!aStatus && !aSingularStatus)
   {
-    gp_Pnt  aP1 = theASurf1->Value(aPnt(1), aPnt(2)),
+    return isOK;
+  }
+
+  const gp_Pnt  aP1 = theASurf1->Value(aPnt(1), aPnt(2)),
                 aP2 = theASurf2->Value(aPnt(3), aPnt(4));
-    gp_Pnt aPInt(0.5*(aP1.XYZ() + aP2.XYZ()));
+  const gp_Pnt aPInt(0.5*(aP1.XYZ() + aP2.XYZ()));
 
   const Standard_Real aSQDist = aPInt.SquareDistance(aP1);
-    if (aSQDist < aTol * aTol)
+  if (aSQDist > aTol * aTol)
   {
+    return isOK;
+  }
+
+  //Found point is true intersection point
   IntSurf_PntOn2S anIP;
   anIP.SetValue(aPInt, aPnt(1), aPnt(2), aPnt(3), aPnt(4));
 
-      if(isTheFirst)
+  //The main idea of checks below is to define if insertion of
-        line->InsertBefore(1,anIP);
+  //addition point (on the boundary) does not lead to invalid
-      else
+  //intersection curve (e.g. having a loop).
-        line->Add(anIP);
+  //
+  //Loops are detected with rotation angle of the Walking-line (WL).
+  //If there is hairpin bend then insertion is forbidden.
 
+  //There are at least two possible problems:
+  //  1. There are some cases when two neighbor points of the WL
+  //      are almost coincident (the distance between them is less
+  //      than Precision::Confusion). It is impossible to define
+  //      rotation angle in these cases. Therefore, points with
+  //      "good" distances should be selected.
+
+  //  2. Intersection point on the surface boundary has highest
+  //      priority in compare with other "middle" points. Therefore,
+  //      if insertion of new point will result in a bend then some
+  //      "middle" points should be deleted in order to provide
+  //      correct insertion.
+
+  //Problem test cases:
+  //  test bugs modalg_5 bug24585_1
+  //  test boolean bcut_complex G7
+  //  test bugs moddata_2 bug469
+
+  if (isTheFirst)
+  {
+    while (line->NbPoints() > 1)
+    {
+      const Standard_Integer aNbPnts = line->NbPoints();
+
+      gp_Pnt aP1, aP2;
+      Standard_Integer aPInd = 1;
+      for (; aPInd <= aNbPnts; aPInd++)
+      {
+        aP1.SetXYZ(line->Value(aPInd).Value().XYZ());
+        if (aP1.SquareDistance(aPInt) > Precision::SquareConfusion())
+          break;
+      }
+
+      for (++aPInd; aPInd <= aNbPnts; aPInd++)
+      {
+        aP2.SetXYZ(line->Value(aPInd).Value().XYZ());
+        if (aP1.SquareDistance(aP2) > Precision::SquareConfusion())
+          break;
+      }
+
+      if (aPInd > aNbPnts)
+      {
+        return isOK;
+      }
+
+      const gp_XYZ aDir01(aP1.XYZ() - aPInt.XYZ());
+      const gp_XYZ aDir12(aP2.XYZ() - aP1.XYZ());
+
+      if (aDir01.Dot(aDir12) > 0.0)
+      {
+        break;
+      }
+
+      line->RemovePoint(1);
+    }
+
+    line->InsertBefore(1, anIP);
     isOK = Standard_True;
   }
+  else
+  {
+    while (line->NbPoints() > 1)
+    {
+      const Standard_Integer aNbPnts = line->NbPoints();
+
+      gp_Pnt aPPrev, aPCurr;
+      Standard_Integer aPInd = aNbPnts;
+      for (; aPInd > 0; aPInd--)
+      {
+        aPCurr.SetXYZ(line->Value(aPInd).Value().XYZ());
+        if (aPCurr.SquareDistance(aPInt) > Precision::SquareConfusion())
+          break;
+      }
+
+      for (--aPInd; aPInd > 0; aPInd--)
+      {
+        aPPrev.SetXYZ(line->Value(aPInd).Value().XYZ());
+        if (aPCurr.SquareDistance(aPPrev) > Precision::SquareConfusion())
+          break;
+      }
+
+      if (aPInd < 1)
+      {
+        return isOK;
+      }
+
+      const gp_XYZ aDirPC(aPCurr.XYZ() - aPPrev.XYZ());
+      const gp_XYZ aDirCN(aPInt.XYZ() - aPCurr.XYZ());
+
+      if (aDirPC.Dot(aDirCN) > 0.0)
+      {
+        break;
+      }
+
+      line->RemovePoint(aNbPnts);
+    }
+
+    line->Add(anIP);
+    isOK = Standard_True;
   }
 
   return isOK;

src/IntWalk/IntWalk_PWalking.hxx

@@ -177,6 +177,12 @@ protected:
   //! theU1, theV1, theU2 and theV2 parameters are initial parameters in
   //! for used numeric algorithms. If isTheFirst == TRUE then
   //! a point on theASurf1 is searched. Otherwise, the point on theASurf2 is searched.
+  //!
+  //! ATTENTION!!!
+  //!   This method can delete some points from the curve if it is necessary
+  //!   (in order to obtain correct result after insertion).
+  //!   Returns TRUE in case of success adding (i.e. can return FALSE even after
+  //!   removing some points).
   Standard_EXPORT Standard_Boolean SeekPointOnBoundary (const Handle(Adaptor3d_HSurface)& theASurf1,
                                                         const Handle(Adaptor3d_HSurface)& theASurf2,
                                                         const Standard_Real theU1,

tests/bugs/modalg_5/bug24585_1

@@ -6,7 +6,7 @@ puts ""
 # Wrong pcurve of the section curve
 ###########################################################
 
-set ExpectedTol 5.6061116035240048e-005
+set ExpectedTol 6.0859390083974326e-005
 set NbCurv_OK 1
 
 restore [locate_data_file bug24585_b1.brep] b1

tests/bugs/modalg_5/bug25319_1

@@ -6,8 +6,6 @@ puts ""
 # Bop Common produces strange results with same shapes.
 ########################################################################
 
-puts "TODO #OCC27896 ALL: Faulty shapes in variables faulty_1 to faulty_"
-
 restore [locate_data_file bug25319_S1.brep] b1
 restore [locate_data_file bug25319_S2.brep] b2
 
@@ -16,5 +14,5 @@ bcommon result b1 b2
 checkprops result -s 1690.81 
 checkshape result
 
-checknbshapes result -vertex 19 -edge 30 -wire 13 -face 13 -shell 1 -solid 1 -compsolid 0 -compound 1 -shape 78
+checknbshapes result -vertex 21 -edge 32 -wire 13 -face 13 -shell 1 -solid 1 -compsolid 0 -compound 1 -shape 82
 checkview -display result -2d -path ${imagedir}/${test_image}.png

tests/bugs/modalg_5/bug25319_2

@@ -6,8 +6,6 @@ puts ""
 # Bop Common produces strange results with same shapes.
 ########################################################################
 
-puts "TODO #OCC27896 ALL: Faulty shapes in variables faulty_1 to faulty_"
-
 restore [locate_data_file bug25319_S1.brep] b1
 restore [locate_data_file bug25319_S2.brep] b2
 
@@ -19,5 +17,5 @@ bcommon result b1 b2
 checkprops result -s 1690.81 
 checkshape result
 
-checknbshapes result -vertex 19 -edge 30 -wire 13 -face 13 -shell 1 -solid 1 -compsolid 0 -compound 1 -shape 78
+checknbshapes result -vertex 21 -edge 32 -wire 13 -face 13 -shell 1 -solid 1 -compsolid 0 -compound 1 -shape 82
 checkview -display result -2d -path ${imagedir}/${test_image}.png

tests/bugs/modalg_6/bug27896

@@ -0,0 +1,40 @@
+puts "============"
+puts "OCC27896"
+puts "============"
+puts ""
+###############################
+## Prm-Prm intersection algo returns wrong result if it is called with start
+## intersection point, which lies in the domain boundary
+###############################
+
+set tol_abs_Tolerance_Reached 1.0e-7
+set tol_rel_Tolerance_Reached 0.1
+set GoodNbCurves 2
+
+restore [locate_data_file bug25319_S1.brep] b1
+restore [locate_data_file bug25319_S2.brep] b2
+explode b1 f
+explode b2 f
+
+# GOOD result before the fix
+set log1 [bopcurves b1_8 b2_17 -2d -p +1.09444207768950010000 +29.00000000000000000000 +0.17740001678466785000 +2.79671571032639710000 -p +0.00000000000000000000 +26.87779254288926400000 +0.17767342824312710000 +2.80622040022304510000]
+
+# BAD result before the fix
+set log2 [bopcurves b1_8 b2_17 -2d -p +1.09444207768949960000 +29.00000000000000000000 +0.17740001678466785000 +2.79671571032639750000 -p +0.00000000000000000000 +26.87779254288926400000 +0.17767342824312710000 +2.80622040022304510000]
+
+regexp {Tolerance Reached=+([-0-9.+eE]+)\n+([-0-9.+eE]+)} ${log1} full Tolerance_Reached1 NbCurv1
+regexp {Tolerance Reached=+([-0-9.+eE]+)\n+([-0-9.+eE]+)} ${log2} full Tolerance_Reached2 NbCurv2
+
+set expected_Tolerance_Reached1 2.2611960020325053e-007
+set expected_Tolerance_Reached2 5.6963104817869286e-006
+
+checkreal "Tolerance Reached" ${Tolerance_Reached1} ${expected_Tolerance_Reached1} ${tol_abs_Tolerance_Reached} ${tol_rel_Tolerance_Reached}
+checkreal "Tolerance Reached" ${Tolerance_Reached2} ${expected_Tolerance_Reached2} ${tol_abs_Tolerance_Reached} ${tol_rel_Tolerance_Reached}
+
+if { $NbCurv1 != $GoodNbCurves } {
+  puts "Error in case 1: $GoodNbCurves curve(s) is expected but $NbCurv1 is found"
+}
+
+if { $NbCurv2 != $GoodNbCurves } {
+  puts "Error in case 2: $GoodNbCurves curve(s) is expected but $NbCurv2 is found"
+}