Modified STEP resource file in order to prevent producing of faces unsuitable for OCCT algorithms due to pcurves translated as lines instead of bsplines in case if tolerance specified in STEP file fully covers the target face.

Test case added.
Modified xdistc2dc2dss command in order to catch output in draw interpretor.

src/GeometryTest/GeometryTest_TestProjCommands.cxx

@@ -112,7 +112,7 @@ static Standard_Integer xdistcc(Draw_Interpretor& , Standard_Integer n, const ch
 //function : xdistc2dc2dss
 //purpose  : 
 //=======================================================================
-static Standard_Integer xdistc2dc2dss(Draw_Interpretor& , Standard_Integer n, const char** a)
+static Standard_Integer xdistc2dc2dss(Draw_Interpretor& di, Standard_Integer n, const char** a)
 {
   if (n < 7)
   {
@@ -132,28 +132,28 @@ static Standard_Integer xdistc2dc2dss(Draw_Interpretor& , Standard_Integer n, co
   aC2d1=DrawTrSurf::GetCurve2d(a[1]);
   if (aC2d1.IsNull())
   {
-    cout<<a[1]<<" is null 2dcurve"<<endl;
+    di<<a[1]<<" is null 2dcurve\n";
     return 0;
   }
 
   aC2d2=DrawTrSurf::GetCurve2d(a[2]);
   if (aC2d2.IsNull())
   {
-    cout<<a[2]<<" is null 2dcurve"<<endl;
+    di<<a[2]<<" is null 2dcurve\n";
     return 0;
   }
 
   aS1=DrawTrSurf::GetSurface(a[3]);
   if (aS1.IsNull())
   {
-    cout<<a[3]<<" is null surface"<<endl;
+    di<<a[3]<<" is null surface\n";
     return 0;
   }
 
   aS2=DrawTrSurf::GetSurface(a[4]);
   if (aS2.IsNull())
   {
-    cout<<a[4]<<" is null surface"<<endl;
+    di<<a[4]<<" is null surface\n";
     return 0;
   }
 
@@ -192,14 +192,16 @@ static Standard_Integer xdistc2dc2dss(Draw_Interpretor& , Standard_Integer n, co
       aMaxDist = aD;
     }
 
-    printf(" T=%lg\tD=%lg\n", aT, aD);
+    char aMsg[256];
+    sprintf(aMsg," T=%lg\tD=%lg\n", aT, aD);
+    di << aMsg;
 
     aMr=new Draw_Marker3D(aP1, Draw_Plus, aColor, iSize);
     dout << aMr;
   }
 
-  cout << "Max distance = "  << aMaxDist << endl;
-  cout << "Param = " << aMaxParam << endl;
+  di << "Max distance = "  << aMaxDist << "\n";
+  di << "Param = " << aMaxParam << "\n";
 
   return 0;
 }

src/XSTEPResource/STEP

@@ -8,8 +8,8 @@
 
 ToSTEP.exec.op : SplitCommonVertex,DirectFaces
 
-FromSTEP.exec.op : FixShape
-
+FromSTEP.exec.op : FixShape, FixFaceSize, FixShape
+FromSTEP.FixFaceSize.Tolerance			: &Runtime.Tolerance
 FromSTEP.FixShape.Tolerance3d			: &Runtime.Tolerance
 FromSTEP.FixShape.MaxTolerance3d		: &Runtime.MaxTolerance
 FromSTEP.FixShape.MinTolerance3d		: 1.e-7

tests/bugs/step/bug27122

@@ -0,0 +1,52 @@
+puts "================"
+puts "OCC27122"
+puts "================"
+puts ""
+#####################################################################
+# STEP import regression: invalid shapes are produced during model translation due to huge face tolerance
+#####################################################################
+
+pload XDE
+
+# procedure to check distance between pcurves
+proc checkdist {c2d1 c2d2 s threshold} {
+    
+  set prop [uplevel xdistc2dc2dss $c2d1 $c2d2 $s $s 0 1 25]
+
+  # get distance value
+  if { ! [regexp {Max distance\s*=\s*([0-9.e+-]+)} $prop res dist] } {
+    puts "Error: cannot get distance value"
+    return
+  }
+
+  # compare with expected value
+  if { $dist < $threshold } {
+    puts "Error: coinciding curves (distance = $dist)"
+  }
+}
+
+#procedure to check thin faces
+proc checkface {face} {
+  uplevel mksurface s $face
+  uplevel explode $face e
+  uplevel mk2dcurve c1 ${face}_1 $face
+  uplevel mk2dcurve c2 ${face}_2 $face
+  
+  uplevel reverse c2
+  uplevel checkdist c1 c2 s 0.03
+  
+  uplevel incmesh $face 0.01
+  set log [uplevel tricheck $face]
+  if {[llength $log] != 0} {
+    puts "Error: failed to mesh face $face"
+  }
+}
+
+stepread [locate_data_file 280696.stp] a *
+renamevar a_1 result
+
+explode result f
+checkface result_3
+checkface result_8
+
+