Bug in Mesh.GetNakedEdges() when using double precision vertices

Rhino Developer
1

I noticed that there is a discrepancy of points returned by Mesh.GetNakedEdges() and the actual points in the Mesh.Vertices collection if double precision vertices are used. It would be nice if that method, which returns Polyline[] with double-precision vertices, uses the double precision vertices if available.

@dale can you put this in the bug tracker?

For a quick reproduction, see this code

public Result RunCommand(RhinoDoc doc, RunMode mode)
{
  Mesh m = new Mesh();
  m.Vertices.UseDoublePrecisionVertices = true;

  Random r = new Random(12345);
  m.Vertices.Add(new Point3d(r.NextDouble(), r.NextDouble(), r.NextDouble()));
  m.Vertices.Add(new Point3d(r.NextDouble(), r.NextDouble(), r.NextDouble()));
  m.Vertices.Add(new Point3d(r.NextDouble(), r.NextDouble(), r.NextDouble()));
  m.Vertices.Add(new Point3d(r.NextDouble(), r.NextDouble(), r.NextDouble()));

  m.Faces.AddFace(0, 1, 2, 3);

  Polyline[] pls = m.GetNakedEdges();
  if (null == pls || !pls.Any())
    return Result.Failure;

  foreach (Polyline pl in pls)
  {
    foreach (Point3d pt in pl)
    {
      Point3d closest = Point3d.Unset;
      double dist = Double.MaxValue;
      for (int i = 0; i < 4; ++i)
      {
        Point3d meshVertex = m.Vertices.Point3dAt(i);
        double d = (meshVertex - pt).SquareLength;
        if (d < dist)
        {
          dist = d;
          closest = meshVertex;
        }
      }

      RhinoApp.WriteLine($"Looking for: {pt.X:R} {pt.Y:R} {pt.Z:R}");
      RhinoApp.WriteLine($"Closest point: {closest.X:R} {closest.Y:R} {closest.Z:R}");
      RhinoApp.WriteLine($"Distance: {pt.DistanceTo(closest):R}");
    }
  }
  
  return Result.Success;
}

Output: 4x discrepancies O(10^-9):

Looking for: 0.066746935248374939 0.070159509778022766 0.774765133857727
Closest point: 0.066746934813795109 0.070159508879370752 0.77476513514982781
Distance: 1.6327766057913135E-09
2

Hi @menno,

I’ve logged the issue.

https://mcneel.myjetbrains.com/youtrack/issue/RH-58919

– Dale

1 Like