Write Mesh and Get Object Instance

gerryark · May 5, 2021, 3:43pm

Using this code to write e mesh object ( really its called many times so maybe the name
is the problem ?)
when I read in Rhino I get a object instance with the mesh inside instead of a mesh object

What to do ?
gd

void DB_RhinoWriter::AddMeshobject(ON_3dPointArray &pArray)
    {
    	  int vertex_count =pArray.Count();
    	  int face_count=vertex_count/3;
    	  if( ! face_count ) return;


    	  ON_Mesh *mesh = new ON_Mesh( face_count, vertex_count, false, false );

    	  for(int i=0;i< vertex_count;i++ )
    		mesh->SetVertex(i,pArray[i] );

    	  int cnt=0;
    	  for(int i=0;i< vertex_count ; i+=3 )
    	  {
    		  mesh->SetTriangle( cnt , i ,i+1, i+2  );
    		  cnt++;
    	  }
    	  mesh->CombineIdenticalVertices(true,true);


    	  if ( mesh->IsValid() )
    	  {
    		        mesh->ComputeVertexNormals();
    			  ON_3dmObjectAttributes attributes;
    			  attributes.m_name = "IxMesh";
    			  attributes.m_layer_index = CurrLayer;
    			  bool bResolveIdAndNameConflicts = true;
    			  Model()->AddModelGeometryComponent(mesh, &attributes, bResolveIdAndNameConflicts);
    	  }
    }

dale · May 5, 2021, 4:28pm

Hi @gerryark,

Nothing in your code snippet stands out as being incorrect. We might need a small sample that we can run here.

Here are two other mesh writing samples if you need some reference.

github.com

mcneel/opennurbs/blob/c20e599d1ff8f08a55d3dddf5b39e37e8b5cac06/example_write/example_write.cpp#L297


    }
  }


  model.AddModelGeometryComponent(&nurbs_surface, nullptr);
  //   model.AddDefaultLayer(L"NURBS surface", ON_Color::UnsetColor);


  return Internal_WriteExampleModel(model, filename, error_log);
}




static bool write_mesh_example( const wchar_t* filename, ON_TextLog& error_log )
{
  // example demonstrates how to create and write a mesh
  ONX_Model model;
  INTERNAL_INITIALIZE_MODEL(model);


  model.AddDefaultLayer(L"mesh", ON_Color::Black);


  // create a mesh to write
  // The mesh is a pyramid with 4 triangular sides and a quadranglar 
  // base.  The mesh has 5 vertices and 5 faces.

github.com

mcneel/opennurbs/blob/c20e599d1ff8f08a55d3dddf5b39e37e8b5cac06/example_write/example_write.cpp#L392




  //////////////////////////////////////////////////////////////
  //////////////////////////////////////////////////////////////


  // Avoid copying the mesh - useful technique for large objects
  model.AddModelGeometryComponentForExperts(false, &mesh, false, nullptr, true);


  return Internal_WriteExampleModel(model, filename, error_log);
}


static bool write_mesh_with_material_example( const wchar_t* filename, ON_TextLog& error_log )
{
  // example demonstrates how to create and write a mesh
  ONX_Model model;
  INTERNAL_INITIALIZE_MODEL(model);


  model.AddDefaultLayer(L"mesh", ON_Color::Black);


  const bool bResolveIdAndNameConflicts = true;
  
  // example demonstrates how to create and write a mesh that uses

– Dale