A closed mesh how can flip it to normal?

Grasshopper GH for Mac
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1

Good day, I have a solid mesh when I import it from a *.stl file. It’s solid but the direction is reversed. I can use _Flip or _FillHoles Command to make it right easily. But I can’t get the right result in my C# project. mesh.Flip(True,True,True) or mesh.Fillholes() don’t work. Does anyone meet this question before?

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image907×383 56.3 KB

0306Files.stl (3.9 KB)

2

Rhino.Geometry.Mesh.UnifyNormals() is probably what you are looking for.

3

Thank you, diff-arch. but it still didn’t work out. Even I used Mesh.Normals.ComputeNormals()also.

4

Hello
it works here.

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image918×761 157 KB

Did you understand that Grasshopper is working on a copy of the Rhino object? So if you make modification on the object you’ll have to bake it in Rhino to have it modified. So you’ll have 2 objects in Rhino.

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5

It’s weird. mesh.flip() works in grasshopper but it didn’t work in RhinoCommon.
Pls, see my code in RhinoCommon. it doesn’t work.

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6

What do you call Rhinocommon. Inside Grasshopper it is Rhinocommon.
Do you you mean working with RhinoCommon inside Visual Studio ?
Does item.Mesh() return a reference or a new mesh.
How can you know the mesh is not flipped ?
…
It is very hard to decipher your problem with limited informations.

7

RhinoCommon plug-in for Rhinoceros 6. :blush:
Mesh.flip didn’t return any new or reference mesh. :cold_face: :cold_face:

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https://developer.rhino3d.com/api/RhinoCommon/html/R_Project_RhinoCommon.htm

8

Hi @hk11,

If you are writing a plug-in command, then this will work:

protected override Result RunCommand(RhinoDoc doc, RunMode mode)
{
  var go = new GetObject();
  go.SetCommandPrompt("Select solid mesh");
  go.GeometryFilter = ObjectType.Mesh;
  go.GeometryAttributeFilter = GeometryAttributeFilter.ClosedMesh;
  go.Get();
  if (go.CommandResult() != Result.Success)
    return go.CommandResult();

  var objref = go.Object(0);
  var mesh = objref.Mesh();
  if (null == mesh)
    return Result.Failure;

  if (mesh.SolidOrientation() < 0)
  {
    var mesh_copy = mesh.DuplicateMesh();
    mesh_copy.Flip(true, true, true);
    doc.Objects.Replace(objref, mesh_copy);
    doc.Views.Redraw();
  }

  return Result.Success;
}

– Dale

9

Thank you, Dale. I got right result now!