/*
* Add an edge to a ring of edges.
*/
static void splice(edge * a, edge * b, point * v)
{
edge *next;
/* b must be the unnattached edge and a must be the previous
ccw edge to b. */
if (Org(a) == v) {
next = Onext(a);
Onext(a) = b;
} else {
next = Dnext(a);
Dnext(a) = b;
}
if (Org(next) == v)
Oprev(next) = b;
else
Dprev(next) = b;
if (Org(b) == v) {
Onext(b) = next;
Oprev(b) = a;
} else {
Dnext(b) = next;
Dprev(b) = a;
}
}
/*
* Creates a new edge and adds it to two rings of edges.
*/
static edge *join(edge * a, point * u, edge * b, point * v, side s)
{
edge *e;
/* u and v are the two vertices which are being joined.
a and b are the two edges associated with u and v res. */
e = make_edge(u, v);
if (s == side::left) {
if (Org(a) == u)
splice(Oprev(a), e, u);
else
splice(Dprev(a), e, u);
splice(b, e, v);
} else {
splice(a, e, u);
if (Org(b) == v)
splice(Oprev(b), e, v);
else
splice(Dprev(b), e, v);
}
return e;
}
void Edge::Draw(unsigned int stamp)
// This is a recursive drawing routine that uses time stamps to
// determine if the edge has already been drawn. This is given
// here for testing purposes only: it is not efficient, and for
// large triangulations the stack might overflow. A better way
// of doing this (and other traversals of the edges) is to maintain
// a list of edges in the corresponding Subdivision object. This
// list should be updated every time an edge is created or destroyed.
{
if (Qedge()->TimeStamp(stamp)) {
// Draw the edge
Point2d a = Org2d();
Point2d b = Dest2d();
bgnline();
v2d((double*)&a);
v2d((double*)&b);
endline();
// visit neighbors
Onext()->Draw(stamp);
Oprev()->Draw(stamp);
Dnext()->Draw(stamp);
Dprev()->Draw(stamp);
}
}
