forall_nodes(vh,G) {
cout << vh << ":";
adjEntry adj;
forall_adj(adj,vh)
cout << " " << adj;
cout << endl;
}
// The check function below tests if the current OrthoRep instance really
// represents a correct orthogonal representation, i.e., it tests if
// * the associated graph is embedded.
// * the external face of the embedding is set
// * the sum of the angles at each vertex is 4
// * if corresponding bend strings are consistent, that is, if e has
// adj. entries adjSrc and adjTgt, then the bend string of adjTgt
// is the string obtained from bend string of adjSrc by reversing the
// sequence and flipping the bits
// * the shape of each face is rectagonal, i.e., if
// #zeros(f) - #ones(f) - 2|f| + sum of angles at vertices in f
// is 4 if f is an internal face or -4 if f is the external face.
bool OrthoRep::check(String &error)
{
const Graph &G = (Graph&) *m_pE;
// is the associated graph embedded ?
if (G.representsCombEmbedding() == false) {
error = "Graph is not embedded!";
return false;
}
// sum of angles at each vertex equals 4 ?
node v;
forall_nodes(v,G)
{
int sumAngles = 0;
adjEntry adj;
forall_adj(adj,v)
sumAngles += angle(adj);
if(sumAngles != 4) {
error.sprintf("Angle sum at vertex %d is %d.",
v->index(), sumAngles);
return false;
}
}
void randomTriconnectedGraph(Graph &G, int n, double p1, double p2)
{
if(n < 4) n = 4;
// start with K_4
completeGraph(G,4);
// nodes[0],...,nodes[i-1] is array of all nodes
Array<node> nodes(n);
node v;
int i = 0;
forall_nodes(v,G)
nodes[i++] = v;
// Will be used below as array of neighbors of v
Array<edge> neighbors(n);
// used to mark neighbors
// 0 = not marked
// 1 = marked left
// 2 = marked right
// 3 = marked both
Array<int> mark(0,n-1,0);
for(; i < n; ++i)
{
// pick a random node
v = nodes[randomNumber(0,i-1)];
// create a new node w such that v is split into v and w
node w = nodes[i] = G.newNode();
// build array of all neighbors
int d = v->degree();
int j = 0;
adjEntry adj;
forall_adj(adj,v)
neighbors[j++] = adj->theEdge();
// mark two distinct neighbors for left
for(j = 2; j > 0; ) {
int r = randomNumber(0,d-1);
if((mark[r] & 1) == 0) {
mark[r] |= 1; --j;
}
}
// mark two distinct neighbors for right
for(j = 2; j > 0; ) {
int r = randomNumber(0,d-1);
if((mark[r] & 2) == 0) {
mark[r] |= 2; --j;
}
}
for(j = 0; j < d; ++j) {
int m = mark[j];
mark[j] = 0;
// decide to with which node each neighbor is connected
// (possible: v, w, or both)
double x = randomDouble(0.0,1.0);
switch(m)
{
case 0:
if(x < p1)
m = 1;
else if(x < p1+p2)
m = 2;
else
m = 3;
break;
case 1:
case 2:
if(x >= p1+p2) m = 3;
break;
}
// move edge or create new one if necessary
edge e = neighbors[j];
switch(m)
{
case 2:
if(v == e->source())
G.moveSource(e,w);
else
G.moveTarget(e,w);
break;
case 3:
G.newEdge(w,e->opposite(v));
break;
}
}
G.newEdge(v,w);
}
}