I think I fixed it. This wasn’t necessary in Rhino 5, because Triangles are represented as 4 vertex polygons, where C and D are the same, but I guess this has changed in Rhino 6?

```
public static Mesh PlotMesh(PachMapReceiver[] Rec_List, System.Drawing.Color[] C)
{
Mesh MM = Hare_to_RhinoMesh(Rec_List[0].Map_Mesh, Rec_List[0].Rec_Vertex);
if (!Rec_List[0].Rec_Vertex)
{
Mesh MF = new Mesh();
for (int i = 0; i < MM.Faces.Count; i++)
{
if (MM.Faces[i].IsQuad)
{
MF.Vertices.Add(MM.Vertices[MM.Faces[i].A]);
MF.Vertices.Add(MM.Vertices[MM.Faces[i].B]);
MF.Vertices.Add(MM.Vertices[MM.Faces[i].C]);
MF.Vertices.Add(MM.Vertices[MM.Faces[i].D]);
int f = MF.Vertices.Count - 4;
MF.Faces.AddFace(f, f + 1, f + 2, f + 3);
MF.VertexColors.SetColor(f, C[i]);
MF.VertexColors.SetColor(f + 1, C[i]);
MF.VertexColors.SetColor(f + 2, C[i]);
MF.VertexColors.SetColor(f + 3, C[i]);
}
else
{
MF.Vertices.Add(MM.Vertices[MM.Faces[i].A]);
MF.Vertices.Add(MM.Vertices[MM.Faces[i].B]);
MF.Vertices.Add(MM.Vertices[MM.Faces[i].C]);
int f = MF.Vertices.Count - 3;
MF.Faces.AddFace(f, f + 1, f + 2);
MF.VertexColors.SetColor(f, C[i]);
MF.VertexColors.SetColor(f + 1, C[i]);
MF.VertexColors.SetColor(f + 2, C[i]);
}
}
return MF;
}
else
{
MM.VertexColors.SetColors(C);
return MM;
}
}
```

Thanks!