/// <summary>
/// Triangulate cell with the provided vertices.
/// </summary>
/// <param name="vertices">The vertices of the cell.</param>
/// <returns>The triangulation.</returns>
private IEnumerable <DefaultTriangulationCell <MIVertex> > Triangulate(List <Vector3D> vertices)
{
IEnumerable <DefaultTriangulationCell <MIVertex> > triangles = null;
// Convert vertices to objects that work with MIConvexHull library
MIVertex[] miVertices = new MIVertex[vertices.Count];
for (int i = 0; i < vertices.Count; i++)
{
miVertices[i] = new MIVertex(vertices[i].X, vertices[i].Y, vertices[i].Z);
}
if (vertices.Count == 4)
{
// MIConvexHull library cannot create a triangulation from a single tetrahedron
triangles = new List <DefaultTriangulationCell <MIVertex> >()
{
new DefaultTriangulationCell <MIVertex>()
{
Vertices = miVertices
}
};
}
else
{
// More vertices are OK so let the library to triangulate them
var triangulation = Triangulation.CreateDelaunay(miVertices);
triangles = triangulation.Cells;
}
return(triangles);
}
protected override int[] FindTriangles()
{
var triangles = new List <int> ();
//Convert vertices to MIVertices
var miVertices = new List <MIVertex> ();
for (int i = 0; i < _vertices.Length; ++i)
{
var miVertex = new MIVertex();
var vertex = _vertices [i];
miVertex.Index = i;
miVertex.Position = new double[3] {
vertex.x, vertex.y, vertex.z
};
miVertices.Add(miVertex);
}
//Generate convex hull + extract triangles
var hull = ConvexHull.Create(miVertices);
foreach (var face in hull.Faces)
{
foreach (var vertex in face.Vertices)
{
triangles.Add(vertex.Index);
}
}
return(triangles.ToArray());
}
/// <summary>
/// Triangulate cell with the provided vertices.
/// </summary>
/// <param name="vertices">The vertices of the cell.</param>
/// <returns>The triangulation.</returns>
private IEnumerable <DefaultTriangulationCell <MIVertex> > Triangulate(List <Vector2D> vertices)
{
if (vertices.Count == 3)
{
// Convert vertices to objects that work with MIConvexHull library
MIVertex[] miVertices = new MIVertex[vertices.Count];
for (int i = 0; i < vertices.Count; i++)
{
miVertices[i] = new MIVertex(vertices[i].X, vertices[i].Y);
}
// MIConvexHull library cannot create a triangulation from a single triangle
return(new List <DefaultTriangulationCell <MIVertex> >()
{
new DefaultTriangulationCell <MIVertex>()
{
Vertices = miVertices
}
});
}
else if (vertices.Count == 4)
{
// There are problems with 4 vertices in MIConvexHull algorithms. There are multiple issues on their github
Vector2D average = new Vector2D();
for (int i = 0; i < vertices.Count; i++)
{
average.X += vertices[i].X;
average.Y += vertices[i].Y;
}
average.X /= vertices.Count;
average.Y /= vertices.Count;
// Convert vertices to objects that work with MIConvexHull library
List <MIVertex> miVertices = new List <MIVertex>(vertices.Count);
for (int i = 0; i < vertices.Count; i++)
{
miVertices.Add(new MIVertex(vertices[i].X, vertices[i].Y));
}
miVertices.Sort(Comparer <MIVertex> .Create((item1, item2) => {
var position1 = item1.Position;
var position2 = item2.Position;
double a1 = ((Math.Atan2(position1[0] - average.X, position1[1] - average.Y) * 180 / Math.PI) + 360) % 360;
double a2 = ((Math.Atan2(position2[0] - average.X, position2[1] - average.Y) * 180 / Math.PI) + 360) % 360;
return((int)(a1 - a2));
}));
var triangles = new List <DefaultTriangulationCell <MIVertex> >();
for (int i = 1; i < miVertices.Count - 1; i++)
{
MIVertex[] tempVertices = { miVertices[0], miVertices[i], miVertices[i + 1] };
triangles.Add(new DefaultTriangulationCell <MIVertex>()
{
Vertices = tempVertices
});
}
return(triangles);
}
else
{
// Convert vertices to objects that work with MIConvexHull library
MIVertex[] miVertices = new MIVertex[vertices.Count];
for (int i = 0; i < vertices.Count; i++)
{
miVertices[i] = new MIVertex(vertices[i].X, vertices[i].Y);
}
// More vertices are OK so let the library to triangulate them
var triangulation = Triangulation.CreateDelaunay(miVertices);
return(triangulation.Cells);
}
}
