Get facet information from PolyFaceMesh

By Adam Nagy

This is the .NET version of this post

Usually it is quite easy to migrate an ARX code to .NET, since it is just a thin wrapper on top of the ARX API. You need to omit the AcDb prefix from the database class types, use foreach instead of a function that creates an iterator, use transactions, and you have most of the below code ready :)

[CommandMethod("PolyTest_PolyFace")]
public void PolyTest_PolyFace()
{
  Editor ed = acApp.DocumentManager.MdiActiveDocument.Editor;
 
  PromptEntityResult per = ed.GetEntity("Select a poly face mesh"); 
  if (per.Status != PromptStatus.OK)
    return;
 
  int color = 0;
 
  Database db = ed.Document.Database;
  using (Transaction tr = db.TransactionManager.StartTransaction())
  {
    BlockTable bt = 
      (BlockTable)tr.GetObject(db.BlockTableId, OpenMode.ForRead);

    BlockTableRecord ms = 
      (BlockTableRecord)tr.GetObject(
        bt[BlockTableRecord.ModelSpace], 
        OpenMode.ForWrite);  
 
    PolyFaceMesh pfm = 
      (PolyFaceMesh)tr.GetObject(per.ObjectId, OpenMode.ForRead);
 
    Point3dCollection vertices = new Point3dCollection();
 
    foreach (ObjectId id in pfm)
    {
      DBObject obj = tr.GetObject(id, OpenMode.ForRead);
 
      if (obj is PolyFaceMeshVertex)
      {
        PolyFaceMeshVertex vertex = (PolyFaceMeshVertex)obj; 
        vertices.Add(vertex.Position);  
      }
      else if (obj is FaceRecord)
      {
        FaceRecord face = (FaceRecord)obj;
 
        Point3dCollection pts = new Point3dCollection(); 
 
        for (short i = 0; i < 4; i++)
        {
          short index = face.GetVertexAt(i);
 
          if (index != 0)
            pts.Add(vertices[Math.Abs(index) - 1]);
        }
 
        // If there are 4 points then we draw crosses
        // (could also be 3)
        if (pts.Count == 4)
        {
          for (int j = 0; j < 2; j++)
          {
            Line line = new Line(pts[j], pts[j + 2]);
            line.ColorIndex = color;
 
            ms.AppendEntity(line);
            tr.AddNewlyCreatedDBObject(line, true);
          }
        }
 
        color = (color + 1) % 7;
      }
    }
 
    tr.Commit(); 
  }
}