public static Vertex Intersect(HalfEdge he0, HalfEdge he1) {
var e1 = he0.Edge;
var e2 = he1.Edge;
if (e1 == null || e2 == null) {
return null;
}
if (e1.RightSite == e2.RightSite) {
return null;
}
var determinant = e1.A*e2.B - e1.B*e2.A;
if (-1.0e-10 < determinant && determinant < 1.0e-10) {
// the edges are parallel
return null;
}
var iX = (e1.C*e2.B - e2.C*e1.B)/determinant;
var iY = (e2.C*e1.A - e1.C*e2.A)/determinant;
HalfEdge he;
Edge e;
if (Voronoi.CompareByYThenX(e1.RightSite, e2.RightSite) < 0) {
he = he0;
e = e1;
} else {
he = he1;
e = e2;
}
var rightOfSite = (iX >= e.RightSite.X);
if ((rightOfSite && he.LeftRight == LR.Side.Left) || (!rightOfSite && he.LeftRight == LR.Side.Right)) {
return null;
}
return Create(iX, iY);
}
private int Bucket(HalfEdge he) {
var theBucket = (int) ((he.YStar - _ymin)/_deltay*_hashSize);
if (theBucket < 0) {
theBucket = 0;
}
if (theBucket >= _hashSize) {
theBucket = _hashSize - 1;
}
return theBucket;
}
public void Remove(HalfEdge he) {
var removalBucket = Bucket(he);
if (he.Vertex != null) {
var previous = _hash[removalBucket];
while (previous.NextInPriorityQueue != he) {
previous = previous.NextInPriorityQueue;
}
previous.NextInPriorityQueue = he.NextInPriorityQueue;
_count--;
he.Vertex = null;
he.NextInPriorityQueue = null;
}
}
public void Insert(HalfEdge he) {
var insertBucket = Bucket(he);
if (insertBucket < _minBucket) {
_minBucket = insertBucket;
}
var previous = _hash[insertBucket];
var next = previous.NextInPriorityQueue;
while ((next = previous.NextInPriorityQueue) != null && (he.YStar > next.YStar || (he.YStar == next.YStar && he.Vertex.X>next.Vertex.X))) {
previous = next;
}
he.NextInPriorityQueue = previous.NextInPriorityQueue;
previous.NextInPriorityQueue = he;
_count++;
}
public EdgeList(float xmin, float deltax, int sqrtNSites) {
_xmin = xmin;
_deltax = deltax;
_hashsize = 2*sqrtNSites;
_hash = new List<HalfEdge>(_hashsize);
for (int i = 0; i < _hashsize; i++) {
_hash.Add(null);
}
LeftEnd = HalfEdge.CreateDummy();
RightEnd = HalfEdge.CreateDummy();
LeftEnd.EdgeListLeftNeighbor = null;
LeftEnd.EdgeListRightNeighbor = RightEnd;
RightEnd.EdgeListLeftNeighbor = LeftEnd;
RightEnd.EdgeListRightNeighbor = null;
_hash[0] = LeftEnd;
_hash[_hashsize-1] = RightEnd;
}
public static HalfEdge Create(Edge edge, LR.Side lr) {
var he = new HalfEdge(edge, lr);
return he;
}
public void Remove(HalfEdge he) {
he.EdgeListLeftNeighbor.EdgeListRightNeighbor = he.EdgeListRightNeighbor;
he.EdgeListRightNeighbor.EdgeListLeftNeighbor = he.EdgeListLeftNeighbor;
he.Edge = Edge.DELETED;
he.EdgeListLeftNeighbor = he.EdgeListRightNeighbor = null;
}
public void Insert(HalfEdge lb, HalfEdge he) {
he.EdgeListLeftNeighbor = lb;
he.EdgeListRightNeighbor = lb.EdgeListRightNeighbor;
lb.EdgeListRightNeighbor.EdgeListLeftNeighbor = he;
lb.EdgeListRightNeighbor = he;
}
private Site RightRegion(HalfEdge he, Site bottomMostSite) {
var edge = he.Edge;
if (edge == null) {
return bottomMostSite;
}
return edge.Sites[he.LeftRight];
}
