private int[] Triangulate()
{
foreach (var vertex in EnumerateVertex())
{
SetConvex(vertex);
SetEar(vertex);
}
while (true)
{
if (Ears.LastOrDefault() is not LinkedListNode <Vertex> vertex)
{
return(null);
}
var prev = vertex.GetPrevious();
var next = vertex.GetNext();
var triangle = Direction == PolygonDirection.ClockWise ? new Triangle(next.Value.Index, vertex.Value.Index, prev.Value.Index) : new Triangle(prev.Value.Index, vertex.Value.Index, next.Value.Index);
Triangles.Add(triangle);
Ears.Remove(vertex);
Vertices.Remove(vertex);
if (Vertices.Count < 3)
{
return(Triangles.SelectMany(t => t.GetVertices(Direction)).ToArray());
}
SetConvex(prev);
SetConvex(next);
SetEar(prev);
SetEar(next);
}
}
private void SetEar(LinkedListNode <Vertex> vertex)
{
if (vertex.Value.IsConvex)
{
var prev = vertex.GetPrevious();
var next = vertex.GetNext();
if (!EnumerateVertex(next, prev).Any(p => PointInTriangle(prev.Value.Position, vertex.Value.Position, next.Value.Position, p.Value.Position)))
{
Ears.Add(vertex);
return;
}
}
Ears.Remove(vertex);
}