public void classifySelf()
{
// we do need to compute the interior angle
double pX, pY, qX, qY;
pX = neighboor1.X - this.X;
pY = neighboor1.Y - this.Y;
qX = neighboor2.X - this.X;
qY = neighboor2.Y - this.Y;
double angle = PolygonVertex.Angle(pX, pY, qX, qY);
if (PolygonVertex.CrossProductSign(pX, pY, qX, qY))
{
// it is exterior angle
angle = 2 * Math.PI - angle;
}
if (neighboor1 < this && neighboor2 < this)
{
// start or split?
type = (angle < Math.PI) ? PolygonVertexType.start : PolygonVertexType.split;
}
else if (neighboor1 > this && neighboor2 > this)
{
// end or merge?
type = (angle < Math.PI) ? PolygonVertexType.end : PolygonVertexType.merge;
}
else
{
type = PolygonVertexType.regular;
}
}
private static bool intersect(PolygonVertex a, PolygonVertex b, PolygonVertex c, PolygonVertex d)
{
return(intersect_1(a.X, b.X, c.X, d.X) &&
intersect_1(a.Y, b.Y, c.Y, d.Y) &&
area(a, b, c) * area(a, b, d) <= 0 &&
area(c, d, a) * area(c, d, b) <= 0);
}
private void HandleRegularVertex(PolygonVertex v)
{
if (v.neighboor2.Y < v.Y)
{
// interior of P lies to the right of v (counterclockwise ordering)
PolygonEdge d = edges.findEdgeEndingIn(v);
PolygonEdge e = edges.findEdgeStartingIn(v);
PolygonVertex dh = helpers[d];
if (dh.type == PolygonVertexType.merge)
{
insertDiagonal(dh, v);
}
T.Remove(d);
T.Add(e);
helpers[e] = v;
}
else
{
// interior of P lies to the left of v
// search in T to find the edge ej directly left of v
Dictionary <PolygonEdge, PointF> interSections = getIntersections(T, v);
// take intersections to the left of vertex & select the leftmost _edge_ from them
PolygonEdge ej = interSections.Where(kvp => kvp.Value.X < v.X).OrderBy(kvp => kvp.Value.X).Last().Key;
if (helpers[ej].type == PolygonVertexType.merge)
{
insertDiagonal(helpers[ej], v);
}
helpers[ej] = v;
}
}
private void HandleStartVertex(PolygonVertex v)
{
PolygonEdge e = edges.findEdgeStartingIn(v);
T.Add(e);
helpers[e] = v;
}
private List <PolygonVertex> findMonotones(PolygonEdge diagonal)
{
PolygonVertex start, end;
List <PolygonVertex> vert = new List <PolygonVertex>();
if (diagonal.edge1.index < diagonal.edge2.index)
{
start = diagonal.edge1;
end = diagonal.edge2;
}
else
{
start = diagonal.edge2;
end = diagonal.edge1;
}
PolygonVertex fixedStart = vertices.Find(v => v == start);
PolygonVertex fixedEnd = vertices.Find(v => v == end);
while (start != end)
{
vert.Add(start);
start = start.neighboor2;
}
vert.Add(end);
fixedStart.neighboor2 = fixedEnd;
fixedEnd.neighboor1 = fixedStart;
vertices = vertices.Except(vert.Except(new[] { diagonal.edge1, diagonal.edge2 })).ToList();
return(vert);
}
private bool sameChain(Dictionary <PolygonVertex, int> chains, PolygonVertex a, PolygonVertex b)
{
if (a.neighboor1 == b || a.neighboor2 == b)
{
return(true);
}
return(chains[a] == chains[b]);
}
public void insertDiagonal(PolygonVertex a, PolygonVertex b, Pen pen = null)
{
if (pen == null)
{
pen = Pens.Red;
}
graphics.DrawLine(pen, a.X, polygonBox.Height - a.Y, b.X, polygonBox.Height - b.Y);
addedDiagonals.Add(new PolygonEdge(a, b));
}
private void HandleEndVertex(PolygonVertex v)
{
PolygonEdge d = edges.findEdgeEndingIn(v);
PolygonVertex dh = helpers[d];
if (dh.type == PolygonVertexType.merge)
{
insertDiagonal(v, dh);
}
T.Remove(d);
}
private void HandleSplitVertex(PolygonVertex v)
{
// search in T to find the edge ej directly left of v
Dictionary <PolygonEdge, PointF> interSections = getIntersections(T, v);
// take intersections to the left of vertex & select the leftmost _edge_ from them
PolygonEdge ej = interSections.Where(kvp => kvp.Value.X < v.X).OrderBy(kvp => kvp.Value.X).Last().Key;
PolygonEdge e = edges.findEdgeStartingIn(v);
insertDiagonal(v, helpers[ej]);
helpers[ej] = v;
T.Add(e);
helpers[e] = v;
}
public bool checkCrossing(PolygonVertex newVertex)
{
PolygonVertex lastPoint = vertices[vertices.Count - 1];
for (int i = 0; i < vertices.Count - 2; i++)
{
if (intersect(vertices[i], vertices[i + 1], newVertex, lastPoint))
{
return(true);
}
}
return(false);
}
public void addVertex(PolygonVertex pv)
{
if (vertices.Count > 2 && checkCrossing(pv))
{
MessageBox.Show("Добавленная вершина создаст в прямоугольнике самопересечение!", "Ошибка");
return;
}
;
pv.index = vertices.Count;
vertices.Add(pv);
graphics.FillEllipse(Brushes.Black, pv.X - 5, (polygonBox.Height - pv.Y - 5), 10, 10);
if (vertices.Count > 1)
{
PolygonVertex prevVertex = vertices[vertices.Count - 2];
pv.neighboor1 = prevVertex;
prevVertex.neighboor2 = pv;
edges.Add(new PolygonEdge(prevVertex, pv));
graphics.DrawLine(Pens.Black, pv.X, polygonBox.Height - pv.Y, prevVertex.X, polygonBox.Height - prevVertex.Y);
}
}
private void HandleMergeVertex(PolygonVertex v)
{
PolygonEdge d = edges.findEdgeEndingIn(v);
PolygonVertex dh = helpers[d];
if (dh.type == PolygonVertexType.merge)
{
insertDiagonal(v, dh);
}
T.Remove(d);
// search in T to find the edge ej directly left of v
Dictionary <PolygonEdge, PointF> interSections = getIntersections(T, v);
// take intersections to the left of vertex & select the leftmost _edge_ from them
PolygonEdge ej = interSections.Where(kvp => kvp.Value.X < v.X).OrderBy(kvp => kvp.Value.X).Last().Key;
if (helpers[ej].type == PolygonVertexType.merge)
{
insertDiagonal(v, helpers[ej]);
}
helpers[ej] = v;
}
public static PolygonEdge findEdgeStartingIn(this List <PolygonEdge> edges, PolygonVertex v)
{
return(edges.Find(e => e.edge1 == v));
}
public PolygonEdge(PolygonVertex e1, PolygonVertex e2)
{
edge1 = e1;
edge2 = e2;
}
private bool orientation(PolygonVertex a, PolygonVertex b, PolygonVertex c)
{
int v = (b.X - a.X) * (c.Y - a.Y) - (b.Y - a.Y) * (c.X - a.X);
return(v > 0);
}
private static float area(PolygonVertex a, PolygonVertex b, PolygonVertex c)
{
return((b.X - a.X) * (c.Y - a.Y) - (b.Y - a.Y) * (c.X - a.X));
}
private Dictionary <PolygonEdge, PointF> getIntersections(HashSet <PolygonEdge> where, PolygonVertex v)
{
var ints = new Dictionary <PolygonEdge, PointF>();
foreach (PolygonEdge e in where)
{
var line = e.toLine();
ints[e] = intersectionPoint(line, v.Y);
}
return(ints);
}
private void triangulateMonotonePolygon(List <PolygonVertex> polygon)
{
List <PolygonVertex> V = polygon.OrderByDescending(v => v.Y).ToList();
Dictionary <PolygonVertex, int> chains = new Dictionary <PolygonVertex, int>();
PolygonVertex chainStart = V[0], chainEnd = V.Last(), lc = chainStart.neighboor2, rc = chainStart.neighboor1;
while (lc != chainEnd)
{
chains[lc] = -1; // left chain
lc = lc.neighboor2;
}
while (rc != chainEnd)
{
chains[rc] = 1; // right chain
rc = rc.neighboor1;
}
Stack <PolygonVertex> S = new Stack <PolygonVertex>();
S.Push(V[0]);
S.Push(V[1]);
for (int j = 2; j < V.Count - 1; j++)
{
if (!sameChain(chains, V[j], S.Peek()))
{
while (S.Count > 0)
{
if (S.Count != 1)
{
insertDiagonal(V[j], S.Peek(), new Pen(Color.SeaGreen, 1f));
}
S.Pop();
}
S.Push(V[j - 1]);
S.Push(V[j]);
}
else
{
PolygonVertex last = S.Pop();
while (S.Count > 0 && (
(orientation(S.Peek(), last, V[j]) && chains[last] == -1) || (!orientation(S.Peek(), last, V[j]) && chains[last] == 1)))
{
last = S.Pop();
insertDiagonal(V[j], last, new Pen(Color.Yellow, 1f));
}
S.Push(last);
S.Push(V[j]);
}
}
S.Pop(); // except the first
while (S.Count > 0)
{
if (S.Count != 1)
{
insertDiagonal(V[V.Count - 1], S.Peek(), Pens.Violet); // diag from u_j to all vert on the stack
}
S.Pop(); // and the last one
}
}