public override Graph GenerateGraph(int vertexCount, int edgePercent, int size = 500)
{
var graph = new Graph();
var random = new Random();
graph.Vertices = Enumerable.Range(0, vertexCount)
.Select(i => new Vertex(i, new Point(random.NextDouble() * size, random.NextDouble() * size)))
.ToDictionary(_ => _.Id, _ => _);
if (graph.Vertices.Count < 2)
{
return(graph);
}
if (graph.Vertices.Count == 2)
{
graph.AddEdge(graph.Vertices[0], graph.Vertices[1]);
return(graph);
}
// соединяем точки гранями, строим триангуляцию Делоне
// чтобы ускорить процесс, найдем самую левую вверхнюю точку, отсортируем все точки по расстоянию от нее
// и соеденим с ближайшей к ней точке, оброзовав первую грань графа.
var first = graph.Vertices[0];
foreach (var v in graph.Vertices.Values)
{
if (v.X < first.X ||
v.X == first.X && v.Y < first.Y)
{
first = v;
}
}
var range = new double[graph.Vertices.Count];
for (var i = 0; i < graph.Vertices.Count; i++)
{
var x = graph.Vertices[i].X - first.X;
var y = graph.Vertices[i].Y - first.Y;
range[i] = x * x + y * y;
}
var sortedVertices = graph.Vertices.Values.ToArray();
Array.Sort(range, sortedVertices);
var vertex = new TrisVertex[sortedVertices.Length];
for (var i = 0; i < sortedVertices.Length; i++)
{
vertex[i] = new TrisVertex(sortedVertices[i]);
}
// создаем первую грань
var tris = new Tris(vertex[0], vertex[1], vertex[2]);
tris.MakeClockwise();
var resultTriangles = new List <Tris>(sortedVertices.Length * 2);
tris[0].Trises.Add(tris);
tris[1].Trises.Add(tris);
tris[2].Trises.Add(tris);
resultTriangles.Add(tris);
var hull = new CircularList <TrisEdge>();
hull.AddItem(new TrisEdge(tris, tris[0], tris[1]));
hull.AddItem(new TrisEdge(tris, tris[1], tris[2]));
hull.AddItem(new TrisEdge(tris, tris[2], tris[0]));
var seekStart = hull.Last;
for (var i = 3; i < vertex.Length; i++)
{
var nextPoint = vertex[i];
CircularItem <TrisEdge> visiblePoint = null;
if (seekStart.Value.EdgeVisibleFrom(nextPoint.Position))
{
visiblePoint = seekStart;
}
else
{
visiblePoint = hull.FindNext(seekStart,
t => t.Value.EdgeVisibleFrom(nextPoint.Position));
}
if (visiblePoint == null)
{
continue;
}
var notVisibleLeft = hull.FindPrevious(visiblePoint,
t => !t.Value.EdgeVisibleFrom(nextPoint.Position));
var notVisibleRight = hull.FindNext(visiblePoint,
t => !t.Value.EdgeVisibleFrom(nextPoint.Position));
if (notVisibleLeft == null || notVisibleRight == null)
{
continue;
}
var visibleLeft = notVisibleLeft.Next;
var edge = visibleLeft.Value;
var hullItem = visibleLeft;
Tris firstEdgeTris = null;
Tris lastEdgeTris = null;
while (hullItem != notVisibleRight)
{
var nextTris = new Tris(edge.A, nextPoint, edge.B);
nextTris[0].Trises.Add(nextTris);
nextTris[1].Trises.Add(nextTris);
nextTris[2].Trises.Add(nextTris);
resultTriangles.Add(nextTris);
// разворачиваем треугольники, чтобы удовлетворяли критерию Делоне
if (FlipIfNeeded(edge.tris, nextTris, nextPoint, out var returnLinkTris))
{
if (firstEdgeTris == null)
{
firstEdgeTris = returnLinkTris;
}
}
if (firstEdgeTris == null)
{
firstEdgeTris = nextTris;
}
lastEdgeTris = nextTris;
hullItem = hullItem.Next;
edge = hullItem.Value;
}
// закрываем дырку
hull.LinkTwoItem(notVisibleLeft, notVisibleRight);
seekStart = hull.AddItemAfter(notVisibleLeft);
seekStart.Value = new TrisEdge(firstEdgeTris, notVisibleLeft.Value.B, nextPoint);
seekStart = hull.AddItemAfter(seekStart);
seekStart.Value = new TrisEdge(lastEdgeTris, nextPoint, notVisibleRight.Value.A);
}
// формируем связи на основе триангуляции
graph.Edges = new List <Edge>(resultTriangles.Count * 2);
foreach (var tr in resultTriangles)
{
graph.AddEdge(tr[0].Original, tr[1].Original);
graph.AddEdge(tr[1].Original, tr[2].Original);
graph.AddEdge(tr[2].Original, tr[0].Original);
}
// пытаемся оставить только нужное кол-во связей, при этом проверяя что все узлы соеденены
var needEdges = (int)(graph.Edges.Count / 100f * edgePercent);
var rnd = new Random();
var testEdges = new List <Edge>(graph.Edges);
while (testEdges.Count > 0 && needEdges < graph.Edges.Count)
{
var removeIndex = rnd.Next(testEdges.Count);
var testEdge = testEdges[removeIndex];
if (graph.HasWayBetweenWithoutEdge(testEdge.A, testEdge.B))
{
graph.RemoveEdge(testEdge.A, testEdge.B);
}
testEdges.RemoveAt(removeIndex);
}
return(graph);
}
