# MeshNgonList class

Namespace: [Rhino.Geometry.Collections](https://developer.rhino3d.com/api/rhinocommon/namespace/rhino.geometry.collections.md) · Assembly: [RhinoCommon](https://developer.rhino3d.com/api/rhinocommon/assembly/rhinocommon.md)

```cs
public class MeshNgonList : IResizableList<MeshNgon>, IList, IReadOnlyList<MeshNgon>
```

Provides access to the ngons and ngon-related functionality of a Mesh. See also the [Mesh.Ngons](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.mesh/ngons.md) property for Ngon functionality details.

## Properties

- [Count](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/count.md): Gets or sets the number of mesh ngons.
- [ICollection<MeshNgon>.IsReadOnly](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/system-collections-generic-icollection-rhino-geometry-meshngon-isreadonly.md)
- [ICollection.IsSynchronized](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/system-collections-icollection-issynchronized.md)
- [ICollection.SyncRoot](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/system-collections-icollection-syncroot.md)
- [IList.IsFixedSize](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/system-collections-ilist-isfixedsize.md)
- [IList.IsReadOnly](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/system-collections-ilist-isreadonly.md)
- [UnsignedCount](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/unsignedcount.md): Gets or sets the number of mesh ngons.

## Indexers

- [IList.this[]](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/system-collections-ilist-this.md)
- [this[]](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/item.md): Returns the mesh ngon at the given index.

## Methods

- [AddNgon](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/addngon.md): Appends a new ngon to the end of the mesh ngon list.
- [AddNgons](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/addngons.md): Appends a list of ngons to the end of the mesh ngon list.
- [AddPlanarNgons](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/addplanarngons.md): (2 overloads) Add an ngon for each group of connected coplanar faces.
- [Clear](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/clear.md): Clears the Ngon list on the mesh.
- [GetEnumerator](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/getenumerator.md): Gets an enumerator that yields all ngons in this collection.
- [GetNgon](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/getngon.md): Returns the mesh ngon at the given index.
- [GetNgonBoundary](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/getngonboundary.md): Get a list of vertices that form the boundary of a face set. This is often use to get ngon boundaries.
- [GetNgonBoundingBox](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/getngonboundingbox.md): (2 overloads) Gets the bounding box of an ngon.
- [GetNgonCenter](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/getngoncenter.md): (2 overloads) Gets the center point of an ngon. This the average of the corner points.
- [GetNgonEdgeCount](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/getngonedgecount.md): Gets the complete edge count of an ngon.
- [GetNgonOuterEdgeCount](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/getngonouteredgecount.md): Gets the outer edge count of an ngon.
- [Insert](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/insert.md): Inserts a mesh ngon at a defined index in this list.
- [IsValid](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/isvalid.md): (2 overloads) Tests an ngon to see if the vertex and face references are valid and pass partial boundary validity checks.
- [NgonBoundaryVertexList](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/ngonboundaryvertexlist.md): Get an ngon's boundary points.
- [NgonHasHoles](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/ngonhasholes.md): Determines whether a ngon has holes.
- [NgonIndexFromFaceIndex](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/ngonindexfromfaceindex.md): Returns the index of a mesh ngon the face belongs to.
- [Orientation](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/orientation.md): Determine if the ngon's boundary orientation matches that of the set of faces it is made from.
- [RemoveAllNgons](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/removeallngons.md): Removes all ngons from the mesh.
- [RemoveAt](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/removeat.md): Removes an ngon from the mesh.
- [RemoveNgons](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/removengons.md): Remove one or more ngons from the mesh.
- [ReverseOuterBoundary](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/reverseouterboundary.md): Reverse the order of the m_vi[] array for an ngon
- [SetNgon](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/setngon.md): Set an ngon in this list.
- [ICollection<MeshNgon>.Add](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/system-collections-generic-icollection-rhino-geometry-meshngon-add.md)
- [ICollection<MeshNgon>.Contains](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/system-collections-generic-icollection-rhino-geometry-meshngon-contains.md)
- [ICollection<MeshNgon>.CopyTo](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/system-collections-generic-icollection-rhino-geometry-meshngon-copyto.md)
- [ICollection<MeshNgon>.Remove](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/system-collections-generic-icollection-rhino-geometry-meshngon-remove.md)
- [IList<MeshNgon>.IndexOf](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/system-collections-generic-ilist-rhino-geometry-meshngon-indexof.md)
- [IList<MeshNgon>.Insert](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/system-collections-generic-ilist-rhino-geometry-meshngon-insert.md)
- [IList<MeshNgon>.RemoveAt](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/system-collections-generic-ilist-rhino-geometry-meshngon-removeat.md)
- [ICollection.CopyTo](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/system-collections-icollection-copyto.md)
- [IEnumerable.GetEnumerator](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/system-collections-ienumerable-getenumerator.md)
- [IList.Add](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/system-collections-ilist-add.md)
- [IList.Contains](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/system-collections-ilist-contains.md)
- [IList.IndexOf](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/system-collections-ilist-indexof.md)
- [IList.Insert](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/system-collections-ilist-insert.md)
- [IList.Remove](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/system-collections-ilist-remove.md)
- [IList.RemoveAt](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.collections.meshngonlist/system-collections-ilist-removeat.md)