VRML mesh shading - Forum Open Cascade Technology

Adam Wnek
Wed, 01/13/2021 - 18:47

Forums:

Data Exchange and Application Framework

Hi,

Im preparing small app converting IGES to VRML. Process consist:

-opening IGES file,

-creating TDocStd_Document,

-meshing all shapes in document,

-writing mesh to WRL file.

Application works as intended, with one small exception. When I use test files from FreeCAD (eg. containing cylinder) output WRL cylinder mesh imported to FreeCAD as desired is smooth on the side and flat on both caps. When using IGES file from other software (MicroStation) output mesh imported to FreeCAD is flat shaded everywhere. Is there any way to set smooth edges according to face angle value during shape meshing or VRML writing process ?

Regards

Adam

Kirill Gavrilov
Wed, 01/13/2021 - 19:09

Any screenshots / test models in IGES and VRML formats / code snippets to look at and suggest what could be wrong?

Adam Wnek
Wed, 01/13/2021 - 22:44

App reads IGES file and saves each shape to separate VRML file. Platform: Linux(Ubuntu) OpenCascade v7.3.0

Reade Setup:

    IGESCAFControl_Reader reader;
   reader.SetColorMode(colorsFlag);//true
   reader.SetLayerMode(layersFlag);//false
   reader.SetNameMode(namesFlag);//true
   Handle(TDocStd_Document) doc= new TDocStd_Document("MDTV-Standard");
   IFSelect_ReturnStatus status=reader.ReadFile(aFilePath.ToCString());

Shape processing:

for(int element=1;element<=shapeLabels.Length();element++){
               TopoDS_Shape shape;
               const TDF_Label& label=shapeLabels.Value(element);
               XCAFDoc_DocumentTool::ShapeTool (doc->Main())->GetShape(label,shape);
               string fileOut=destPath+separator()+prefix+"_"+to_string(element)+".wrl";
               procesThread(shape,fileOut);
}

Meshing:

void FileConverter::shapeToMesh(TopoDS_Shape& shape)
{
BRepMesh_IncrementalMesh mesher(shape, linearDeflection, Standard_False, angularDeflection);
mesher.Perform();
}

VRML write :

bool FileConverter::writeShapeToVRML(TopoDS_Shape &shape, const TCollection_AsciiString &destinationPath)
{
   TopoDS_Compound res;
   BRep_Builder builder;
   VrmlAPI_Writer writer;
   builder.MakeCompound( res );
   if(!shape.IsNull()){
       builder.Add(res,shape);
       writer.Write(res,destinationPath.ToCString());
       return true;
   }else{
       return false;
   }
}

Sceens:

FreeCad Iges:

https://photos.app.goo.gl/46t7BzPgsodyXnw8A

FreeCad VRML:

https://photos.app.goo.gl/s3fLLkjnNbN2PzPE6

MicroStation iges:

https://photos.app.goo.gl/WiTiV1aqNiN5axJ6A

Microstation VRML rounded caps:

https://photos.app.goo.gl/zYT7aTAzALTcGfkg7

As you can see rounded cylinder caps are smooth shaded. cylinder side is not.

Microsation VRML flat caps:
https://photos.app.goo.gl/bo3fBHqBe5MvAfir7

Regards

Adam

Adam Wnek
Wed, 01/13/2021 - 23:30

App reads IGES file and saves each shape to separate VRML file. Platform: Linux(Ubuntu) OpenCascade v7.3.0

Reade Setup:

    IGESCAFControl_Reader reader;
    reader.SetColorMode(colorsFlag);//true
    reader.SetLayerMode(layersFlag);//false
    reader.SetNameMode(namesFlag);//true
    Handle(TDocStd_Document) doc= new TDocStd_Document("MDTV-Standard");
    IFSelect_ReturnStatus status=reader.ReadFile(aFilePath.ToCString());

Shape processing:

for(int element=1;element<=shapeLabels.Length();element++){
                TopoDS_Shape shape;
                const TDF_Label& label=shapeLabels.Value(element);
                XCAFDoc_DocumentTool::ShapeTool (doc->Main())->GetShape(label,shape);
                string fileOut=destPath+separator()+prefix+"_"+to_string(element)+".wrl";
                procesThread(shape,fileOut);
}

Meshing:

void FileConverter::shapeToMesh(TopoDS_Shape& shape)
{
BRepMesh_IncrementalMesh mesher(shape, linearDeflection, Standard_False, angularDeflection);
mesher.Perform();
}

VRML write :

bool FileConverter::writeShapeToVRML(TopoDS_Shape &shape, const TCollection_AsciiString &destinationPath)
{
    TopoDS_Compound res;
    BRep_Builder builder;
    VrmlAPI_Writer writer;
    builder.MakeCompound( res );
    if(!shape.IsNull()){
        builder.Add(res,shape);
        writer.Write(res,destinationPath.ToCString());
        return true;
    }else{
        return false;
    }
}

Sceens:

FreeCad Iges:

https://photos.app.goo.gl/46t7BzPgsodyXnw8A

FreeCad VRML:

https://photos.app.goo.gl/s3fLLkjnNbN2PzPE6

MicroStation iges:

https://photos.app.goo.gl/WiTiV1aqNiN5axJ6A

Microstation VRML rounded caps:

https://photos.app.goo.gl/zYT7aTAzALTcGfkg7

As you can see rounded cylinder caps are smooth shaded. cylinder side is not.

Microsation VRML flat caps:
https://photos.app.goo.gl/bo3fBHqBe5MvAfir7

Regards

Adam

Adam Wnek
Thu, 01/14/2021 - 12:23

App reads IGES file and saves each shape to separate VRML file. Platform: Linux(Ubuntu) OpenCascade v7.3.0

Reader Setup:

    IGESCAFControl_Reader reader;
    reader.SetColorMode(colorsFlag);//true
    reader.SetLayerMode(layersFlag);//false
    reader.SetNameMode(namesFlag);//true
    Handle(TDocStd_Document) doc= new TDocStd_Document("MDTV-Standard");
    IFSelect_ReturnStatus status=reader.ReadFile(aFilePath.ToCString());

Shape processing:

for(int element=1;element<=shapeLabels.Length();element++){
                TopoDS_Shape shape;
                const TDF_Label& label=shapeLabels.Value(element);
                XCAFDoc_DocumentTool::ShapeTool (doc->Main())->GetShape(label,shape);
                string fileOut=destPath+separator()+prefix+"_"+to_string(element)+".wrl";
                procesThread(shape,fileOut);
}

Meshing:

void FileConverter::shapeToMesh(TopoDS_Shape& shape)
{
BRepMesh_IncrementalMesh mesher(shape, linearDeflection, Standard_False, angularDeflection);//linearDeflection=0.5;angularDeflection=15
mesher.Perform();
}

VRML write :

bool FileConverter::writeShapeToVRML(TopoDS_Shape &shape, const TCollection_AsciiString &destinationPath)
{
    TopoDS_Compound res;
    BRep_Builder builder;
    VrmlAPI_Writer writer;
    builder.MakeCompound( res );
    if(!shape.IsNull()){
        builder.Add(res,shape);
        writer.Write(res,destinationPath.ToCString());
        return true;
    }else{
        return false;
    }
}

Regards

Adam

Attachments:

freeCad_IGES.jpg

freeCad_wrl.jpg

microstation_IGES.jpg

microstation_wrl.jpg

Adam Wnek
Wed, 01/13/2021 - 22:16

Hi. code splits each iges shape to separate VRML file. Platform linux (Ubuntu) opencascade version 7.3.0

iges reader setup:
    IGESCAFControl_Reader reader;
   reader.SetColorMode(colorsFlag);//true
   reader.SetLayerMode(layersFlag);//false
   reader.SetNameMode(namesFlag);//true
   const TCollection_ExtendedString storageFormat="MDTV-Standard";
   Handle(TDocStd_Document) doc= new TDocStd_Document(storageFormat);
   IFSelect_ReturnStatus status=reader.ReadFile(aFilePath.ToCString());

Processing each shape:

meshing shape:

void FileConverter::shapeToMesh(TopoDS_Shape& shape)
{

//linearDeflection=2;

       //angularDeflection=15
       BRepMesh_IncrementalMesh mesher(shape, linearDeflection, Standard_False, angularDeflection);
        mesher.Perform();
   }

Save VRML:
     bool FileConverter::writeShapeToVRML(TopoDS_Shape &shape, const TCollection_AsciiString &destinationPath)
    {
        TopoDS_Compound res;
        BRep_Builder builder;
       VrmlAPI_Writer writer;
       builder.MakeCompound( res );
       if(!shape.IsNull()){
           builder.Add(res,shape);
           writer.Write(res,destinationPath.ToCString());
           return true;
       }else{
           return false;
       }
   }

FreeCad Iges screen:

https://photos.app.goo.gl/JsRLiKrrvoP7r5r86

FreeCad VRML screen:
https://photos.app.goo.gl/RRrsaUZS8QYRaLBa9

Microstation Iges screen:

https://photos.app.goo.gl/SwB4zzTLLP1gVCm29

Microstation VRML screen:

https://photos.app.goo.gl/5y96rSgk6V7Kyhi56

Adam Wnek
Thu, 01/14/2021 - 09:04

App reads IGES file and saves each shape to separate VRML file. Platform: Linux(Ubuntu) OpenCascade v7.3.0

Reade Setup:

    IGESCAFControl_Reader reader;
    reader.SetColorMode(colorsFlag);//true
    reader.SetLayerMode(layersFlag);//false
    reader.SetNameMode(namesFlag);//true
    Handle(TDocStd_Document) doc= new TDocStd_Document("MDTV-Standard");
    IFSelect_ReturnStatus status=reader.ReadFile(aFilePath.ToCString());

Shape processing:

for(int element=1;element<=shapeLabels.Length();element++){
                TopoDS_Shape shape;
                const TDF_Label& label=shapeLabels.Value(element);
                XCAFDoc_DocumentTool::ShapeTool (doc->Main())->GetShape(label,shape);
                string fileOut=destPath+separator()+prefix+"_"+to_string(element)+".wrl";
                procesThread(shape,fileOut);
}

Meshing:

void FileConverter::shapeToMesh(TopoDS_Shape& shape)
{
BRepMesh_IncrementalMesh mesher(shape, linearDeflection, Standard_False, angularDeflection);
mesher.Perform();
}

VRML write :

bool FileConverter::writeShapeToVRML(TopoDS_Shape &shape, const TCollection_AsciiString &destinationPath)
{
    TopoDS_Compound res;
    BRep_Builder builder;
    VrmlAPI_Writer writer;
    builder.MakeCompound( res );
    if(!shape.IsNull()){
        builder.Add(res,shape);
        writer.Write(res,destinationPath.ToCString());
        return true;
    }else{
        return false;
    }
}

Sceens:

FreeCad Iges:

https://photos.app.goo.gl/46t7BzPgsodyXnw8A

FreeCad VRML:

https://photos.app.goo.gl/s3fLLkjnNbN2PzPE6

MicroStation iges:

https://photos.app.goo.gl/WiTiV1aqNiN5axJ6A

Microstation VRML rounded caps:

https://photos.app.goo.gl/zYT7aTAzALTcGfkg7

As you can see rounded cylinder caps are smooth shaded. cylinder side is not.

Microsation VRML flat caps:
https://photos.app.goo.gl/bo3fBHqBe5MvAfir7

Regards

Adam

Adam Wnek
Thu, 01/14/2021 - 12:18

For some reason I cant submit my reply

Regards

Adam

Adam Wnek
Thu, 01/14/2021 - 16:19

Hi.

I have one more question regarding meshing shapes and write them toVRML format.

VrmlAPI_Wrier creates wrl file with default material definition:
Shape {
      appearance DEF __defaultMaterialFace Appearance {
        material Material {
          ambientIntensity 1
          diffuseColor      0.780392 0.568627 0.113725
          emissiveColor     0.329412 0.223529 0.027451
          shininess         0.022
          specularColor     0.992157 0.941176 0.807843
        }
      }

Where in OpenCascade can I find methods to change This default material parameters?

Thanks in advance

Adam

Kirill Gavrilov
Thu, 01/14/2021 - 16:27

You may just grep "__defaultMaterialFace" in OCCT source code to find where it is defined. I'm not familiar with VRML writer API though to say if/how it can be overridden.

Handle(VrmlData_Appearance) VrmlData_ShapeConvert::defaultMaterialFace () const
{
  static char aNodeName[] = "__defaultMaterialFace";
  Handle(VrmlData_Appearance) anAppearance =
    Handle(VrmlData_Appearance)::DownCast(myScene.FindNode(aNodeName));
  if (anAppearance.IsNull()) {
    const Handle(VrmlData_Material) aMaterial =
      new VrmlData_Material (myScene, 0L, 1.0, 0.022, 0.);
    aMaterial->SetDiffuseColor (Quantity_Color(0.780392, 0.568627, 0.113725,
                                               Quantity_TOC_sRGB));
...

Adam Wnek
Fri, 01/15/2021 - 04:09

Thanks for help. I red through source code and finally to get my own material written as default I had to subclass VrmlAPI_Writer. Still don't know why some meshes shading is solid not smooth.

Regards

Adam