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 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 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;
}
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;
}