public static void triangulate <T>(Project <T> project, FList <T> poly, FList <TriIdx> result)
{
var N = poly.Count;
result.Clear();
if (N < 3)
{
return;
}
result.Capacity = poly.Count - 2;
if (N == 3)
{
result.Add(new TriIdx(0, 1, 2));
return;
}
var vinfo = new vertex_info[N];
vinfo[0] = new vertex_info(project(poly[0]), 0);
for (int i = 1; i < N - 1; ++i)
{
vinfo[i] = new vertex_info(project(poly[i]), i);
vinfo[i].prev = vinfo[i - 1];
vinfo[i - 1].next = vinfo[i];
}
vinfo[N - 1] = new vertex_info(project(poly[N - 1]), N - 1);
vinfo[N - 1].prev = vinfo[N - 2];
vinfo[N - 1].next = vinfo[0];
vinfo[0].prev = vinfo[N - 1];
vinfo[N - 2].next = vinfo[N - 1];
for (int i = 0; i < N; ++i)
{
vinfo[i].recompute();
}
var begin = vinfo[0];
removeDegeneracies(ref begin, result);
doTriangulate(begin, result);
}
/// <summary>
/// 全要素を取り除く
/// </summary>
public void Clear()
{
_List.Clear();
}
static bool findDiagonal(vertex_info begin, out vertex_info v1, out vertex_info v2)
{
vertex_info t;
var heap = new FList <vertex_info>();
v1 = begin;
do
{
heap.Clear();
for (v2 = v1.next.next; v2 != v1.prev; v2 = v2.next)
{
if (!internalToAngle(v1.next, v1, v1.prev, v2.p) ||
!internalToAngle(v2.next, v2, v2.prev, v1.p))
{
continue;
}
PriorityQueue <vertex_info> .PushHeap(heap, v2, new vertex_info_l2norm_inc_ordering(v1));
}
while (heap.Count != 0)
{
v2 = PriorityQueue <vertex_info> .PopHeap(heap, new vertex_info_l2norm_inc_ordering(v1));
// test whether v1-v2 is a valid diagonal.
var v_min_x = Math.Min(v1.p.X, v2.p.X);
var v_max_x = Math.Max(v1.p.X, v2.p.X);
bool intersected = false;
for (t = v1.next; !intersected && t != v1.prev; t = t.next)
{
vertex_info u = t.next;
if (t == v2 || u == v2)
{
continue;
}
var l1 = orient2d(v1.p, v2.p, t.p);
var l2 = orient2d(v1.p, v2.p, u.p);
if ((l1 > 0.0 && l2 > 0.0) || (l1 < 0.0 && l2 < 0.0))
{
// both on the same side; no intersection
continue;
}
var dx13 = v1.p.X - t.p.X;
var dy13 = v1.p.Y - t.p.Y;
var dx43 = u.p.X - t.p.X;
var dy43 = u.p.Y - t.p.Y;
var dx21 = v2.p.X - v1.p.X;
var dy21 = v2.p.Y - v1.p.Y;
var ua_n = dx43 * dy13 - dy43 * dx13;
var ub_n = dx21 * dy13 - dy21 * dx13;
var u_d = dy43 * dx21 - dx43 * dy21;
if (Math.Abs(u_d) < element.Epsilon)
{
// parallel
if (Math.Abs(ua_n) < element.Epsilon)
{
// colinear
if (Math.Max(t.p.X, u.p.X) >= v_min_x && Math.Min(t.p.X, u.p.X) <= v_max_x)
{
// colinear and intersecting
intersected = true;
}
}
}
else
{
// not parallel
var ua = ua_n / u_d;
var ub = ub_n / u_d;
if (0 <= ua && ua <= 1 && 0 <= ub && ub <= 1)
{
intersected = true;
}
}
}
if (!intersected)
{
// test whether midpoint winding == 1
var mid = (v1.p + v2.p) / 2;
if (windingNumber(begin, mid) == 1)
{
// this diagonal is ok
return(true);
}
}
}
// couldn't find a diagonal from v1 that was ok.
v1 = v1.next;
} while (v1 != begin);
return(false);
}