/// <summary>
///
/// </summary>
/// <param name="field"></param>
/// <param name="selection"></param>
/// <returns></returns>
public static Mesh MeshSelection(this Grid3d field, IEnumerable <int> selection)
{
var mesh = new Mesh();
var verts = mesh.Vertices;
var faces = mesh.Faces;
(var dx, var dy) = ((Vec2d)field.Scale * 0.5);
// add vertices
foreach (int index in selection)
{
var p = field.CoordinateAt(index);
verts.Add(p.X - dx, p.Y - dy, p.Z);
verts.Add(p.X + dx, p.Y - dy, p.Z);
verts.Add(p.X - dx, p.Y + dy, p.Z);
verts.Add(p.X + dx, p.Y + dy, p.Z);
}
// add faces
for (int i = 0; i < verts.Count; i += 4)
{
faces.AddFace(i, i + 1, i + 3, i + 2);
}
return(mesh);
}