public void FaceTriangulationTest()
{
Triangulation result = new Triangulation();
foreach (var face in m_dcel.InnerFaces)
{
result.AddTriangulation(Triangulator.Triangulate(face));
}
var triangles = result.Triangles.ToList();
Assert.AreEqual(8, triangles.Count);
Assert.IsTrue(triangles.TrueForAll(t => t.IsClockwise()));
}
public void AddTriangulationTest()
{
var tr = new Triangle(v1, v2, v4);
var tr2 = new Triangle();
var T2 = new Triangulation(T.Triangles);
var T3 = new Triangulation(new List <Triangle>()
{
tr, tr2
});
T2.AddTriangulation(T3);
Assert.AreEqual(4, T2.Triangles.Count);
}
/// <summary>
/// Triangulate a collection of dcel faces.
/// </summary>
/// <param name="faces"></param>
/// <param name="setTwinPointers"> whether the triangulation should set twin pointers </param>
/// <returns></returns>
public static Triangulation Triangulate(IEnumerable <Face> faces, bool setTwinPointers = true)
{
var T = new Triangulation();
foreach (var face in faces)
{
T.AddTriangulation(Triangulate(face, false));
}
if (setTwinPointers)
{
T.SetTwinPointers();
}
return(T);
}
/// <summary>
/// Triangulates the polygon recursively.
/// Finds the leftmost point and creates a triangle with that or splits polygon in two.
/// </summary>
/// <param name="vertices"></param>
/// <returns></returns>
private static Triangulation TriangulateRecursive(List <Vector2> vertices)
{
if (vertices.Count == 3)
{
return(new Triangulation(vertices));
}
var triangulation = new Triangulation();
//Find leftmost vertex
var leftVertex = LeftMost(vertices);
var index = vertices.IndexOf(leftVertex);
var prevVertex = vertices[MathUtil.PositiveMod(index - 1, vertices.Count)];
var nextVertex = vertices[MathUtil.PositiveMod(index + 1, vertices.Count)];
//Create triangle with diagonal
Debug.Assert(leftVertex != prevVertex && leftVertex != nextVertex && prevVertex != nextVertex);
var triangle = new Triangle(prevVertex, leftVertex, nextVertex);
//check for other vertices inside the candidate triangle
var baseline = new Line(prevVertex, nextVertex);
float distance = -1f;
int diagonalIndex = -1;
for (int i = 0; i < vertices.Count; i++)
{
var v = vertices[i];
if (v != leftVertex && v != prevVertex && v != nextVertex &&
triangle.Contains(v))
{
if (baseline.DistanceToPoint(v) > distance)
{
distance = baseline.DistanceToPoint(v);
diagonalIndex = i;
}
}
}
//Do Recursive call
if (diagonalIndex == -1) //didn't change
{
if (!triangle.IsClockwise())
{
// shouldnt happen but in case it does
// reverse triangle
triangle = new Triangle(triangle.P0, triangle.P2, triangle.P1);
}
triangulation.AddTriangle(triangle);
vertices.Remove(leftVertex);
triangulation.AddTriangulation(TriangulateRecursive(vertices));
}
else
{
var minIndex = Mathf.Min(index, diagonalIndex);
var maxIndex = Mathf.Max(index, diagonalIndex);
var poly1List = vertices.Skip(minIndex).Take(maxIndex - minIndex + 1).ToList();
var poly2List = vertices.Skip(maxIndex).Concat(vertices.Take(minIndex + 1)).ToList();
triangulation.AddTriangulation(TriangulateRecursive(poly1List));
triangulation.AddTriangulation(TriangulateRecursive(poly2List));
}
return(triangulation);
}
