///<summary>
/// Creates a new QuadEdge connecting the destination of a to the origin of
/// b, in such a way that all three have the same left face after the
/// connection is complete. Additionally, the data pointers of the new edge
/// are set.
///</summary>
///<param name="a"></param>
///<param name="b"></param>
///<returns>the connected edge</returns>
public static QuadEdge Connect(QuadEdge a, QuadEdge b)
{
QuadEdge e = MakeEdge(a.Destination, b.Origin);
Splice(e, a.LeftNext);
Splice(e.Sym(), b);
return(e);
}
///<summary>
/// Tests if this quadedge and another have the same line segment geometry
/// with the same orientation.
///</summary>
///<param name="qe">a quadege</param>
///<returns>true if the quadedges are based on the same line segment</returns>
public Boolean EqualsOriented(QuadEdge qe)
{
if (Origin.Equals(qe.Origin) &&
Destination.Equals(qe.Destination))
{
return(true);
}
return(false);
}
///<summary>
/// Tests if this quadedge and another have the same line segment geometry,
///</summary>
///<param name="qe">a quadege</param>
///<returns>true if the quadedges are based on the same line segment regardless of orientation regardless of orientation.</returns>
public Boolean EqualsNonOriented(QuadEdge qe)
{
if (EqualsOriented(qe))
{
return(true);
}
if (EqualsOriented(qe.Sym()))
{
return(true);
}
return(false);
}
///<summary>
/// Turns an edge counterclockwise inside its enclosing quadrilateral.
///</summary>
///<param name="e">the quadedge to turn</param>
public static void Swap(QuadEdge e)
{
QuadEdge a = e.OriginPrev;
QuadEdge b = e.Sym().OriginPrev;
Splice(e, a);
Splice(e.Sym(), b);
Splice(e, a.LeftNext);
Splice(e.Sym(), b.LeftNext);
e.Origin = a.Destination;
e.Destination = b.Destination;
}
///<summary>
/// Splices two edges together or apart.
/// Splice affects the two edge rings around the origins of a and b, and, independently, the two
/// edge rings around the left faces of <tt>a</tt> and <tt>b</tt>.
/// In each case, (i) if the two rings are distinct,
/// Splice will combine them into one, or (ii) if the two are the same ring, Splice will break it
/// into two separate pieces. Thus, Splice can be used both to attach the two edges together, and
/// to break them apart.
///</summary>
///<param name="a"></param>
///<param name="b"></param>
public static void Splice(QuadEdge a, QuadEdge b)
{
QuadEdge alpha = a.OriginNext.Rot;
QuadEdge beta = b.OriginNext.Rot;
QuadEdge t1 = b.OriginNext;
QuadEdge t2 = a.OriginNext;
QuadEdge t3 = beta.OriginNext;
QuadEdge t4 = alpha.OriginNext;
a.Next = t1;
b.Next = t2;
alpha.Next = t3;
beta.Next = t4;
}
///<summary>
/// Creates a new QuadEdge quartet from {@link Vertex} o to {@link Vertex} d.
///</summary>
///<param name="o">the origin Vertex</param>
///<param name="d">the destination Vertex</param>
///<returns>the new QuadEdge quartet</returns>
public static QuadEdge MakeEdge(FVec3 o, FVec3 d)
{
QuadEdge q0 = new QuadEdge();
QuadEdge q1 = new QuadEdge();
QuadEdge q2 = new QuadEdge();
QuadEdge q3 = new QuadEdge();
q0.Rot = q1;
q1.Rot = q2;
q2.Rot = q3;
q3.Rot = q0;
q0.Next = q0;
q1.Next = q3;
q2.Next = q2;
q3.Next = q1;
QuadEdge baseQE = q0;
baseQE.Origin = o;
baseQE.Destination = d;
return(baseQE);
}
///<summary>
/// Marks this quadedge as being deleted.
/// This does not free the memory used by
/// this quadedge quartet, but indicates
/// that this edge no longer participates
/// in a subdivision.
///</summary>
public void Delete()
{
_rot = null;
}