/// <summary>
/// Adds two triangles forming a quad to the MeshCreator. Adds the vertices
/// to the MeshCreator if they aren't already added.
/// </summary>
/// <param name="a">The first vertex in clockwise order.</param>
/// <param name="b">The second vertex in clockwise order.</param>
/// <param name="c">The third vertex in clockwise order.</param>
/// <param name="d">The fourth vertex in clockwise order.</param>
public void AddQuad(MeshVertex a, MeshVertex b, MeshVertex c, MeshVertex d)
{
AddTriangle(a, b, c);
AddTriangle(a, c, d);
}