0025357: STL writer does not check the given shape for existing triangulation and remeshes shape using BRepMesh in force mode.

StlTransfer.cxx, function StlTransfer::BuildIncrementalMesh(...) fills the StlMesh_Mesh. Before this fix the StlTransfer always force meshing of the passed shape.

Now meshing is completely removed from the StlTransfer. StlWriter can return error status now, for example, if a mesh of the passed shape is empty. In this case file will be not created.

Added test case bugs/xde/bug25357

Avoid the warning on gcc compiler.
Test scripts were modified according to the fix.
     1) bug23192, bug22670, bug23193: removed "isParallel" flag from the command
         arguments. Manually meshing of the shape (as far as meshing was removed
         from STL writer).
     2) bug22898: before the fix writestl always remeshes the shape with a
         deflection, related to the boundery box of the shape. For "hammer" shape
         there is a 38.9076 deflection for mesh. Differences between before writing
         and after reading are dedicated to fact that stl writes triangulation as
         an elements of the spahe (like faces, edges etc.)

src/QABugs/QABugs_2.cxx

@@ -33,6 +33,7 @@
 #include <BRep_Tool.hxx>
 #include <BRepAlgoAPI_Section.hxx>
 #include <BRepAlgo_Section.hxx>
+#include <BRepMesh_IncrementalMesh.hxx>
 #include <Precision.hxx>
 #include <Standard_ErrorHandler.hxx>
 
@@ -183,8 +184,8 @@ static Standard_Integer OCC1048 (Draw_Interpretor& di, Standard_Integer argc, co
 
   Standard_Real theDeflection = 0.006;
   Handle(StlMesh_Mesh) theStlMesh = new StlMesh_Mesh;
-  StlTransfer::BuildIncrementalMesh(aShape, theDeflection, Standard_False, theStlMesh);
-
+  BRepMesh_IncrementalMesh aMesh(aShape, theDeflection);
+  StlTransfer::RetrieveMesh(aShape, theStlMesh);
   Standard_Integer NBTRIANGLES = theStlMesh->NbTriangles();
   di<<"Info: Number of triangles = "<<NBTRIANGLES<<"\n";
 

src/StlAPI/StlAPI.cdl

@@ -25,12 +25,21 @@ uses
     StlMesh
      
 is 
+	enumeration ErrorStatus is 
+		---Purpose: Set of statuses to indicate a type of the error
+		-- occurred during data retrieving and writing operations.
+		StatusOK,
+		MeshIsEmpty,
+		CannotOpenFile
+
+    end ErrorStatus;
+
     class Writer; 
     class Reader; 
     
     Write(aShape      : in Shape from TopoDS;  
           aFile       : in CString from Standard;
-    	  aAsciiMode  : in Boolean from Standard = Standard_True);
+    	  aAsciiMode  : in Boolean from Standard = Standard_True) returns ErrorStatus from StlAPI;
 	  ---Purpose : Convert and write shape to STL format.
 	  --         file is written in binary if aAsciiMode is False
 	  --         otherwise it is written in Ascii (by default)

src/StlAPI/StlAPI.cxx

@@ -15,13 +15,13 @@
 #include <StlAPI_Writer.hxx>
 #include <StlAPI_Reader.hxx>
 
-void StlAPI::Write(const TopoDS_Shape& aShape,
+StlAPI_ErrorStatus StlAPI::Write(const TopoDS_Shape& aShape,
 		   const Standard_CString aFile,
 		   const Standard_Boolean aAsciiMode) 
 {
   StlAPI_Writer writer;
   writer.ASCIIMode() = aAsciiMode;
-  writer.Write (aShape, aFile);
+  return writer.Write (aShape, aFile);
 }
 
 

src/StlAPI/StlAPI_Writer.cdl

@@ -21,34 +21,12 @@ class Writer from StlAPI
 
 uses
     Shape from TopoDS,
-    Mesh from StlMesh
+    Mesh from StlMesh,
+	ErrorStatus from StlAPI
 is
-    Create;
+	Create;
    	 ---Purpose: Creates a writer object with
-   	 -- default parameters: ASCIIMode, RelativeMode, SetCoefficent,
-   	 -- SetDeflection. These parameters may be modified. 
-
-    SetDeflection(me: in out; aDeflection : in Real from Standard);
-    	---Purpose: Sets the deflection of the meshing algorithm. 
-    	--    Deflection is used, only if relative mode is false
-
-    SetCoefficient(me: in out; aCoefficient : in Real from Standard);
-    	---Purpose: Sets the coeffiecient for computation of deflection through 
-    	--          relative size of shape. Default value = 0.001
-
-    RelativeMode(me: in out) returns Boolean;
-       	---C++: return &
-    	---Purpose: Returns the address to the
-    	-- flag defining the relative mode for writing the file.
-    	-- This address may be used to either read or change the flag.
-    	-- If the mode returns True (default value), the
-    	-- deflection is calculated from the relative size of the
-    	-- shape. If the mode returns False, the user defined deflection is used. 
-    	-- Example
-    	-- Read:
-    	-- Standard_Boolean val = Writer.RelativeMode( );
-    	-- Modify:
-    	-- Writer.RelativeMode( ) = Standard_True; 
+   	 -- default parameters: ASCIIMode.
         
     ASCIIMode(me: in out) returns Boolean;
       	---C++: return &
@@ -61,14 +39,11 @@ is
         
     Write(me         : in out; 
           aShape     : Shape from TopoDS; 
-          aFileName  : CString from Standard; 
-          InParallel : Boolean from Standard = Standard_False);
+          aFileName  : CString from Standard) returns ErrorStatus from StlAPI;
     	---Purpose: Converts a given shape to STL format and writes it to file with a given filename.
+		--- \return the error state.
     
 fields
-    theRelativeMode : Boolean from Standard;
     theASCIIMode    : Boolean from Standard;
-    theDeflection   : Real from Standard;
-    theCoefficient   : Real from Standard;
     theStlMesh      : Mesh from StlMesh;
 end Writer;

src/StlAPI/StlAPI_Writer.cxx

@@ -19,30 +19,10 @@
 #include <BRepBndLib.hxx>
 #include <OSD_Path.hxx>
 
-#define MAX2(X, Y)      (  Abs(X) > Abs(Y)? Abs(X) : Abs(Y) )
-#define MAX3(X, Y, Z)   ( MAX2 ( MAX2(X,Y) , Z) )
-
 StlAPI_Writer::StlAPI_Writer()
 {
   theStlMesh = new StlMesh_Mesh;
   theASCIIMode = Standard_True;
-  theDeflection = 0.01;
-  theRelativeMode = Standard_True;
-  theCoefficient = 0.001;
-}
-
-void StlAPI_Writer::SetDeflection(const Standard_Real aDeflection) 
-{
-  theDeflection = aDeflection;
-}
-void StlAPI_Writer::SetCoefficient(const Standard_Real aCoefficient) 
-{
-  theCoefficient = aCoefficient;
-}
-
-Standard_Boolean& StlAPI_Writer::RelativeMode() 
-{
-  return theRelativeMode;
 }
 
 Standard_Boolean& StlAPI_Writer::ASCIIMode() 
@@ -50,23 +30,26 @@ Standard_Boolean& StlAPI_Writer::ASCIIMode()
   return theASCIIMode;
 }
 
-void StlAPI_Writer::Write(const TopoDS_Shape& theShape, const Standard_CString theFileName, const Standard_Boolean theInParallel) 
+StlAPI_ErrorStatus StlAPI_Writer::Write(const TopoDS_Shape& theShape, const Standard_CString theFileName)
 {
   OSD_Path aFile(theFileName);
-  if (theRelativeMode) {
-    Standard_Real aXmin, aYmin, aZmin, aXmax, aYmax, aZmax;
-    Bnd_Box Total;
-    BRepBndLib::Add(theShape, Total);
-    Total.Get(aXmin, aYmin, aZmin, aXmax, aYmax, aZmax);
-    theDeflection = MAX3(aXmax-aXmin , aYmax-aYmin , aZmax-aZmin)*theCoefficient;
-  }
-  StlTransfer::BuildIncrementalMesh(theShape, theDeflection, theInParallel, theStlMesh);
+  StlTransfer::RetrieveMesh(theShape, theStlMesh);
+
+  if (theStlMesh.IsNull() || theStlMesh->IsEmpty())
+    return StlAPI_MeshIsEmpty;
+
   // Write the built mesh
+  Standard_Boolean wasFileOpened = Standard_False;
   if (theASCIIMode) {
-    RWStl::WriteAscii(theStlMesh, aFile);
+    wasFileOpened = RWStl::WriteAscii(theStlMesh, aFile);
     }  
   else {
-    RWStl::WriteBinary(theStlMesh, aFile);
+    wasFileOpened = RWStl::WriteBinary(theStlMesh, aFile);
     }
+
+  if (!wasFileOpened)
+    return StlAPI_CannotOpenFile;
+
+  return StlAPI_StatusOK;
 }
 

src/StlTransfer/StlTransfer.cdl

@@ -17,11 +17,9 @@
 package StlTransfer 
 
 	---Purpose: The  package   Algorithm  for Meshing   implements
-	--          facilities to compute  the Mesh data-structure, as
-	--          defined in package StlMesh, from a shape of package
-	--          TopoDS.  The triangulation  is  computed  with the
-	--          Delaunay      algorithm   implemented in   package
-	--          BRepMesh.  The  result   is  stored  in  the  mesh
+	--          facilities to retrieve the Mesh data-structure from a shape of package
+	--          TopoDS.  The triangulation  should be computed before.  
+	--          The  result   is  stored  in  the  mesh
 	--          data-structure Mesh from package StlMesh.
 	--          
 
@@ -31,11 +29,9 @@ uses
     TopoDS
 
 is
-    BuildIncrementalMesh (Shape      : in      Shape from TopoDS; 
-    	       	    	  Deflection : in      Real  from Standard;
-    	       	    	  InParallel : in      Boolean from Standard;
-    	       	          Mesh       : Mesh  from StlMesh)
-     raises ConstructionError;
+    RetrieveMesh (Shape      : in      Shape from TopoDS; 
+    	       	  Mesh       : Mesh  from StlMesh);
+		---Purpose: Retrieve a Mesh data-structure from the Shape, convert and store it into the Mesh. 		  
 end StlTransfer;
 
 

src/StlTransfer/StlTransfer.cxx

@@ -108,16 +108,9 @@ static void Normal(const TopoDS_Face&  aFace,
   }
   
 }
-void StlTransfer::BuildIncrementalMesh (const TopoDS_Shape&  Shape,
-										const Standard_Real  Deflection,
-										const Standard_Boolean  InParallel,
+void StlTransfer::RetrieveMesh (const TopoDS_Shape&  Shape,
 										const Handle(StlMesh_Mesh)& Mesh)
 {
-  if (Deflection <= Precision::Confusion ()) {
-    Standard_ConstructionError::Raise ("StlTransfer::BuildIncrementalMesh");
-    }
-  
-  BRepMesh_IncrementalMesh aMesher(Shape, Deflection, Standard_False, 0.5, InParallel);
   for (TopExp_Explorer itf(Shape,TopAbs_FACE); itf.More(); itf.Next()) {
     TopoDS_Face face = TopoDS::Face(itf.Current());
     TopLoc_Location Loc, loc;
@@ -125,7 +118,7 @@ void StlTransfer::BuildIncrementalMesh (const TopoDS_Shape&  Shape,
     if (theTriangulation.IsNull()) continue; //Meshing was not done for this face!
     Poly_Array1OfTriangle theTriangles(1,theTriangulation->NbTriangles());
     theTriangles.Assign(theTriangulation->Triangles());
-    Mesh->AddDomain (Deflection);
+    Mesh->AddDomain (theTriangulation->Deflection());
     
     TColgp_Array1OfPnt thePoints(1, theTriangulation->NbNodes());
     thePoints.Assign(theTriangulation->Nodes());

src/XSDRAWSTLVRML/XSDRAWSTLVRML.cxx

@@ -92,21 +92,25 @@ extern Standard_Boolean VDisplayAISObject (const TCollection_AsciiString& theNam
 static Standard_Integer writestl
 (Draw_Interpretor& di, Standard_Integer argc, const char** argv)
 {
-  if (argc < 3 || argc > 5) {
+  if (argc < 3 || argc > 4) {
     di << "Use: " << argv[0]
-    << " shape file [ascii/binary (0/1) : 1 by default] [InParallel (0/1) : 0 by default]" << "\n";
+    << " shape file [ascii/binary (0/1) : 1 by default]" << "\n";
   } else {
     TopoDS_Shape aShape = DBRep::Get(argv[1]);
     Standard_Boolean isASCIIMode = Standard_False;
-    Standard_Boolean isInParallel = Standard_False;
-    if (argc > 3) {
+    if (argc == 4) {
       isASCIIMode = (Draw::Atoi(argv[3]) == 0);
-      if (argc > 4)
-        isInParallel = (Draw::Atoi(argv[4]) == 1);
     }
     StlAPI_Writer aWriter;
     aWriter.ASCIIMode() = isASCIIMode;
-    aWriter.Write (aShape, argv[2], isInParallel);
+    StlAPI_ErrorStatus aStatus = aWriter.Write (aShape, argv[2]);
+
+    switch (aStatus)
+    {
+    case StlAPI_MeshIsEmpty: di << "** Error **: Mesh is empty. Please, compute triangulation before."; break;
+    case StlAPI_CannotOpenFile: di << "** Error **: Cannot create/open a file with the passed name."; break;
+    case StlAPI_StatusOK: default: break;
+    }
   }
   return 0;
 }

tests/bugs/fclasses/bug23192_1

@@ -14,11 +14,11 @@ set aFile $imagedir/${test_image}.stl
 file delete ${aFile}
 
 set anASCIImode 1
-set InParallel 0
 
 box res 10 10 10
+incmesh res 0.1
 
-writestl res ${aFile} ${anASCIImode} ${InParallel}
+writestl res ${aFile} ${anASCIImode}
 catch {exec chmod 777 ${aFile}}
 
 if { [file exists ${aFile}] } {

tests/bugs/fclasses/bug23192_2

@@ -14,11 +14,11 @@ set aFile $imagedir/${test_image}.stl
 file delete ${aFile}
 
 set anASCIImode 0
-set InParallel 0
 
 box res 10 10 10
+incmesh res 0.1
 
-writestl res ${aFile} ${anASCIImode} ${InParallel}
+writestl res ${aFile} ${anASCIImode}
 catch {exec chmod 777 ${aFile}}
 
 if { [file exists ${aFile}] } {

tests/bugs/xde/bug22670_1

@@ -13,6 +13,8 @@ readstl res_mesh [locate_data_file OMF6391_box.stl]
 set aFile ${imagedir}/OCC22670.stl
 file delete ${aFile}
 
+incmesh res_mesh 0.1
+
 set anASCIImode 0
 writestl res_mesh ${aFile} ${anASCIImode}
 catch {exec chmod 777 ${aFile}}

tests/bugs/xde/bug22670_2

@@ -25,10 +25,11 @@ if { [catch { readstl res_mesh $filepath } catch_result] } {
 
     set aFile $imagedir/${test_image}.stl
     catch {exec rm -f ${aFile}}
+     
+    incmesh res_mesh 0.1   
 
     set anASCIImode 0
-    set InParallel 1
-    writestl res_mesh ${aFile} ${anASCIImode} ${InParallel}
+    writestl res_mesh ${aFile} ${anASCIImode}
     catch {exec chmod 777 ${aFile}}
 
     readstl result ${aFile}

tests/bugs/xde/bug22898

@@ -42,6 +42,7 @@ tolerance step_1
 checkarea step_1 3.978e8 1e6 0.001
 
 # STL
+incmesh hammer 38.9076
 writestl hammer $imagedir/hammer.stl 
 readstl stl $imagedir/hammer.stl
 checkshape stl

tests/bugs/xde/bug23193

@@ -12,6 +12,7 @@ set aFile $imagedir/bug23193_sample.stl
 
 vinit
 stepread [locate_data_file bug23193_sample.stp] a *
+incmesh a_1 1
 writestl a_1 ${aFile} 0
 
 meshfromstl m1 ${aFile}

tests/bugs/xde/bug25357

@@ -0,0 +1,47 @@
+puts "=========="
+puts "OCC25357"
+puts "=========="
+puts ""
+#######################################################################################
+# STL writer does not check the given shape for existing triangulation and remeshes 
+# shape using BRepMesh in force mode
+#######################################################################################
+
+set aFile ${imagedir}/${test_image}.stl
+file delete -force ${aFile}
+
+set anASCIImode 0
+
+ptorus res 10 8
+incmesh res 0.5
+
+#decho off
+set LogBefore [trinfo res]
+#decho on
+
+writestl res ${aFile} ${anASCIImode}
+
+#decho off
+set LogAfter [trinfo res]
+#decho on
+
+set status 1
+if { ![file exists ${aFile}] } {
+  set status 0
+}
+
+# Check file size
+set filesize [ file size ${aFile} ]
+if { ${filesize} == 0 } {
+  set status 0
+}
+
+if { $LogBefore != $LogAfter } {
+  set status 0
+}
+
+if {$status == 1} {
+  puts "OK: STL writer check given shape"
+} else {
+  puts "Error: STL writer does not check given shape"
+}