Failed to find Node for given afront point - Poly2Tri

Question

I am want to cut a hole in a polygon:

|-----------------------|
|                       |
|      |------|         |
|      |      |         |
|      |------|         |
|                       |
|-----------------------|       

The outer has the following coords (double):

-0,76 ; -1,5
1,86  ; -1,5
-0,76 ; 1,5
1,86  ; 1,5

The inner coords (double) are:

0,65 ; -0,66
1,57 ; -0,66
0,65 ; 0,75
1,57 ; 0,75

I want to use for this Poly2Tri an created a Polygon with the first four points.

PolygonPoint[] pts = new PolygonPoint[shape.Length];
for (int i = 0; i < shape.Length; i++)
{
  pts[i] = new PolygonPoint((shape[i].X), (shape[i].Y));
  points.Add(shape[i]);
}
Polygon p = new Polygon(pts);

After that I added a hole with the second four points.

p.AddHole(new Polygon(ptsO));

Now I called:

P2T.Triangulate(p);

I get the following exception: Failed to find Node for given afront point

How do I fix this exception?

Answer 1

I'm not familiar with this library, but the outer 4 points are not in counterclockwise order as you specified them. Instead, they cross, where the grey line connects point3 back to point0:

Try adding them in counterclockwise order instead. You may need to create the inner loop in clockwise order, depending on Poly2Tri's conventions.

Update

Just found some documentation here:

3. Input/Output

Simple Polygon outer bounary vertices oriented in counter clockwise direction.

[snip]

Here are the all vertices for holes oriented in clockwise direction;