private void SetNormals()
{
var normals = new Vector3DCollection()
{
new Vector3D(0, 0, -1),
new Vector3D(0, 0, 1),
new Vector3D(1, 0, 0),
new Vector3D(-1, 0, 0),
new Vector3D(0, 1, 0),
new Vector3D(0, -1, 0)
};
var n2 = new Vector3DCollection()
{
normals[0] + normals[3] + normals[5],
normals[0] + normals[2] + normals[5],
normals[0] + normals[3] + normals[4],
normals[0] + normals[2] + normals[4],
normals[1] + normals[5] + normals[3],
normals[1] + normals[2] + normals[5],
normals[1] + normals[3] + normals[4],
normals[2] + normals[4] + normals[1],
};
n2.ToList().ForEach(x => x.Normalize());
D.Normals = n2;
}