Hi,

I am new to rhino wip rhino-common but I would really like to test new ngon functionality.

What I would like to do is to create simple mesh let say with 5 vertices and get information about adjacency of faces adjacent to edges.

Thank you.

Hi,

I am new to rhino wip rhino-common but I would really like to test new ngon functionality.

What I would like to do is to create simple mesh let say with 5 vertices and get information about adjacency of faces adjacent to edges.

Thank you.

Ngonal faces from Rhinocommon or Grasshopper plugin c# question

Here is a mesh with ngons that you can try: Dodecahedron.3dm (34.2 KB)

This block of code *should* be able to make one:

```
/// <summary>
/// Creates a planar mesh from a closed, planar polyline curve
/// </summary>
public static Mesh MeshFromPolyline(PolylineCurve curve)
{
Mesh mesh = null;
if (null != curve &&
curve.IsClosed &&
curve.IsPlanar() &&
curve.PointCount >= 4
)
{
if (4 == curve.PointCount)
{
mesh = new Mesh();
var a = mesh.Vertices.Add(curve.Point(0));
var b = mesh.Vertices.Add(curve.Point(1));
var c = mesh.Vertices.Add(curve.Point(2));
mesh.Faces.AddFace(a, b, c);
}
else if (5 == curve.PointCount)
{
mesh = new Mesh();
var a = mesh.Vertices.Add(curve.Point(0));
var b = mesh.Vertices.Add(curve.Point(1));
var c = mesh.Vertices.Add(curve.Point(2));
var d = mesh.Vertices.Add(curve.Point(3));
mesh.Faces.AddFace(a, b, c, d);
}
else
{
mesh = Mesh.CreateFromClosedPolyline(curve.ToPolyline());
if (null != mesh)
{
var vertices = new List<int>(mesh.Vertices.Count);
for (var vi = 0; vi < mesh.Vertices.Count; vi++)
vertices.Add(vi);
var faces = new List<int>(mesh.Faces.Count);
for (var fi = 0; fi < mesh.Faces.Count; fi++)
faces.Add(fi);
var ngon = MeshNgon.Create(vertices.ToArray(), faces.ToArray());
if (null != ngon)
mesh.Ngons.AddNgon(ngon);
}
}
if (null != mesh)
{
mesh.FaceNormals.ComputeFaceNormals();
mesh.Normals.ComputeNormals();
mesh.Compact();
if (!mesh.IsValid)
mesh = null;
}
}
return mesh;
}
```

– Dale

Thank you for a reply.

Do N-Gons have any adjacency information to other ngons?

How should I find all ngons that are adjacent to one of the ngon?

Do ngons know about each other? I tried to look into mesh edges, vertices and faces, they do not have any property to get connected ngon or similar.

This is only face - face adjacency. Maybe @dale has a better advice on this, but this works too, I have not sorted out Mesh Edge - To Ngon and vertex To Ngon relation, and also do not know what happens when mesh face or ngon is deleted, but this works when ngons are just initialized:

**Adjacency**

**Iterate over mesh faces in ngon and get connected faces**

**if that face does not belong to the same ngon add to adjacency list**

```
List<int>[] faceAdj = new List<int>[mymesh.Ngons.Count];
for (int i = 0; i < mymesh.Ngons.Count; i++)
{
List<int> faceAdjTemp = new List<int>();
uint[] meshFaceIdInCurrentNGon = mymesh.Ngons[i].FaceIndexList();
for (int j = 0; j < meshFaceIdInCurrentNGon.Length; j++)
{
int[] id = mymesh.Faces.AdjacentFaces((int)meshFaceIdInCurrentNGon[j]);
for (int k = 0; k < id.Length; k++)
{
int ngonID = mymesh.Ngons.NgonIndexFromFaceIndex(id[k]);
if (ngonID != i && !faceAdjTemp.Contains(ngonID))
faceAdjTemp.Add(ngonID);
}
}
faceAdj[i] = faceAdjTemp;
}
```

But I agree it would be nice if ngons have some adjacency properties within each other