0026443: Offset surface hangs up

D0 computation of offset surface simplification.

Update of test-case according to the new behavior
Test-cases for issue #26443

src/Geom/Geom_OffsetSurface.cxx

@@ -1589,26 +1589,28 @@ Standard_Boolean Geom_OffsetSurface::VOsculatingSurface(const Standard_Real U, c
 
 void Geom_OffsetSurface::SetD0(const Standard_Real U, const Standard_Real V, 
                                gp_Pnt& P,
-                               const gp_Vec& D1U, const gp_Vec& D1V) const
+                               const gp_Vec& D1U, const gp_Vec& D1V) const // First Derivative
 {
-  Handle(Geom_BSplineSurface) L;
-  Standard_Boolean IsOpposite=Standard_False;
-  const Standard_Boolean AlongU = UOsculatingSurface(U,V,IsOpposite,L); 
-  const Standard_Boolean AlongV = VOsculatingSurface(U,V,IsOpposite,L);
-  const Standard_Real signe = ((AlongV || AlongU) && IsOpposite)? -1. : 1.;
-
   const Standard_Real MagTol=0.000000001;
-  gp_Dir Normal;
-  CSLib_NormalStatus NStatus;
-  CSLib::Normal (D1U, D1V, MagTol, NStatus, Normal);
 
-  if (NStatus == CSLib_Defined) // akm - only in singularities && !AlongU && !AlongV) 
+  gp_Vec aNorm = D1U.Crossed(D1V);
+  if (aNorm.SquareMagnitude() > MagTol * MagTol)
   {
-    P.SetXYZ(P.XYZ() + offsetValue * Normal.XYZ());
+    // Non singular case. Simple computations.
+    aNorm.Normalize();
+    P.SetXYZ(P.XYZ() + offsetValue * aNorm.XYZ());
   }
   else
   {
-    const Standard_Integer MaxOrder=3;
+    Standard_Boolean AlongU = Standard_False,
+                     AlongV = Standard_False;
+    Handle(Geom_BSplineSurface) L;
+    Standard_Boolean IsOpposite=Standard_False;
+    AlongU = UOsculatingSurface(U,V,IsOpposite,L); 
+    AlongV = VOsculatingSurface(U,V,IsOpposite,L);
+    gp_Dir Normal;
+    CSLib_NormalStatus NStatus;
+    Standard_Integer MaxOrder=3;
     TColgp_Array2OfVec DerNUV(0,MaxOrder,0,MaxOrder);
     TColgp_Array2OfVec DerSurf(0,MaxOrder+1,0,MaxOrder+1);
     Standard_Integer OrderU,OrderV;
@@ -1618,6 +1620,10 @@ void Geom_OffsetSurface::SetD0(const Standard_Real U, const Standard_Real V,
     DerSurf.SetValue(0, 1, D1V);
     derivatives(MaxOrder,1,U,V,basisSurf,0,0,AlongU,AlongV,L,DerNUV,DerSurf);
 
+    Standard_Real signe = 1.0;
+    if ((AlongV || AlongU) && IsOpposite)
+      signe = -1;
+
     CSLib::Normal(MaxOrder,DerNUV,MagTol,U,V,Umin,Umax,Vmin,Vmax,NStatus,Normal,OrderU,OrderV);
     if (NStatus == CSLib_Defined) 
       P.SetXYZ(P.XYZ() + offsetValue * signe * Normal.XYZ());
@@ -1652,27 +1658,29 @@ void Geom_OffsetSurface::SetD1(const Standard_Real U, const Standard_Real V,
 
   // Check offset side.
   Handle(Geom_BSplineSurface) L;
+  Standard_Boolean AlongU = Standard_False,
+                   AlongV = Standard_False;
   Standard_Boolean IsOpposite=Standard_False;
-  const Standard_Boolean AlongU = UOsculatingSurface(U,V,IsOpposite,L); 
+  AlongU = UOsculatingSurface(U,V,IsOpposite,L); 
-  const Standard_Boolean AlongV = VOsculatingSurface(U,V,IsOpposite,L);
+  AlongV = VOsculatingSurface(U,V,IsOpposite,L);
-  const Standard_Real signe = ((AlongV || AlongU) && IsOpposite)? -1. : 1.;
+  Standard_Real signe = 1.0;
+  if ((AlongV || AlongU) && IsOpposite) 
+    signe = -1.0;
 
-  gp_Dir Normal;
+  Standard_Integer MaxOrder = 0;
-  CSLib_NormalStatus NStatus;
+  gp_Vec aNorm = D1U.Crossed(D1V);
-  CSLib::Normal (D1U, D1V, MagTol, NStatus, Normal);
+  if (aNorm.SquareMagnitude() > MagTol * MagTol)
-
-  Standard_Integer MaxOrder;
-  if (NStatus == CSLib_Defined) 
   {
     MaxOrder=0;
 
     if (!AlongV && !AlongU)
     {
-      // AlongU or AlongV leads to more complex D1 computation
+      // AlongU or AlongV leads to more complex D1 computations,
-      // Try to compute D0 and D1 much simpler
+      // try to compute D0 and D1 much simpler.
-      P.SetXYZ(P.XYZ() + offsetValue * signe * Normal.XYZ());
+      aNorm.Normalize();
+      P.SetXYZ(P.XYZ() + offsetValue * signe * aNorm.XYZ());
 
-      gp_Vec aN0(Normal.XYZ()), aN1U, aN1V;
+      gp_Vec aN0(aNorm.XYZ()), aN1U, aN1V;
       Standard_Real aScale = (D1U^D1V).Dot(aN0);
       aN1U.SetX(D2UU.Y() * D1V.Z() + D1U.Y() * D2UV.Z() 
               - D2UU.Z() * D1V.Y() - D1U.Z() * D2UV.Y());
@@ -1715,6 +1723,8 @@ void Geom_OffsetSurface::SetD1(const Standard_Real U, const Standard_Real V,
   DerSurf.SetValue(0, 2, D2VV);
   derivatives(MaxOrder,2,U,V,basisSurf,1,1,AlongU,AlongV,L,DerNUV,DerSurf);
 
+  gp_Dir Normal;
+  CSLib_NormalStatus NStatus;
   CSLib::Normal(MaxOrder,DerNUV,MagTol,U,V,Umin,Umax,Vmin,Vmax,NStatus,Normal,OrderU,OrderV);
   if (NStatus != CSLib_Defined) Geom_UndefinedValue::Raise();
 

tests/bugs/modalg_6/bug26443_1

@@ -0,0 +1,20 @@
+puts "========"
+puts "OCC26443"
+puts "========"
+puts ""
+###########################
+# Offset surface hangs up
+###########################
+
+smallview
+
+restore [locate_data_file OCC26443-shell_1.brep] a
+
+chrono h reset
+dchrono h start
+offsetshape r a -2
+chrono h stop
+dchrono h show
+fit
+
+set only_screen_axo 1

tests/bugs/modalg_6/bug26443_2

@@ -0,0 +1,20 @@
+puts "========"
+puts "OCC26443"
+puts "========"
+puts ""
+###########################
+# Offset surface hangs up
+###########################
+
+smallview
+
+restore [locate_data_file OCC26443-shell_2.brep] a
+
+chrono h reset
+dchrono h start
+offsetshape r a -2
+chrono h stop
+dchrono h show
+fit
+
+set only_screen_axo 1

tests/offset/with_intersect_80/L6

@@ -1,5 +1,6 @@
 puts "TODO OCC26577 All: Error :  is WRONG because number of EDGE entities in shape"
 puts "TODO OCC26577 All: Error :  is WRONG because number of SHELL entities in shape"
+puts "TODO OCC26577 All: Faulty shapes in variables faulty_1 to faulty"
 restore [locate_data_file bug26663_test_offset_L6.brep] s
 OFFSETSHAPE ${off_param} {} ${calcul} ${type}
 checknbshapes result -ref [lrange [nbshapes s] 8 19]

tests/offset/with_intersect_80/L8

@@ -1,6 +1,5 @@
 puts "TODO OCC26577 All: Error :  is WRONG because number of EDGE entities in shape"
 puts "TODO OCC26577 All: Error :  is WRONG because number of SHELL entities in shape"
-puts "TODO OCC26577 Windows: Faulty shapes in variables faulty_1 to faulty"
 restore [locate_data_file bug26663_test_offset_L8.brep] s
 OFFSETSHAPE ${off_param} {} ${calcul} ${type}
 checknbshapes result -ref [lrange [nbshapes s] 8 19]