public static List <Polyline> DelaunayTriangulation(this Polyline outerCurve, List <Polyline> innerCurves = null, double offsetDistance = -0.001, bool conformingDelaunay = true)
{
if (outerCurve == null)
{
BH.Engine.Base.Compute.RecordError("Cannot perform Delaunay Triangulation on an outer curve that is set to null.");
return(new List <Polyline>());
}
// Create a zero length list if no holes input
if (innerCurves == null)
{
innerCurves = new List <Polyline>();
}
double area = outerCurve.Area();
for (int x = 0; x < innerCurves.Count; x++)
{
Polyline pLine = outerCurve.BooleanDifference(new List <Polyline> {
innerCurves[x]
})[0];
if (pLine.Area() != area)
{
//The boolean difference returned a different polyline - offset this inner curve
innerCurves[x] = innerCurves[x].Offset(offsetDistance);
}
}
// Get the transformation matrix
Plane plane = outerCurve.IFitPlane();
Vector normal = plane.Normal;
List <Point> vertices = outerCurve.IDiscontinuityPoints();
Point refPoint = vertices.Min();
Point refPointP = BH.Engine.Geometry.Create.Point(refPoint.X, refPoint.Y, 0);
Vector zVector = BH.Engine.Geometry.Create.Vector(0, 0, 1);
Vector rotationVector = normal.CrossProduct(zVector).Normalise();
double rotationAngle = normal.Angle(zVector);
TransformMatrix transformMatrix = BH.Engine.Geometry.Create.RotationMatrix(vertices.Min(), rotationVector, rotationAngle);
// Get the translation vector
Vector translateVector = refPointP - refPoint;
// Transform the original input curve/s
Polyline transformedCurve = Modify.Translate(outerCurve.Transform(transformMatrix), translateVector);
List <Polyline> transformedHole = new List <Polyline>();
foreach (Polyline h in innerCurves)
{
if (h.IsCoplanar(outerCurve))
{
transformedHole.Add(Modify.Translate(h.Transform(transformMatrix), translateVector));
}
}
// Convert geometry to Triangle inputs
TriangleNet.Geometry.Polygon parentPolygon = new TriangleNet.Geometry.Polygon();
List <TriangleNet.Geometry.Vertex> parentVertices = new List <TriangleNet.Geometry.Vertex>();
foreach (Point point in transformedCurve.IDiscontinuityPoints())
{
parentPolygon.Add(new TriangleNet.Geometry.Vertex(point.X, point.Y));
parentVertices.Add(new TriangleNet.Geometry.Vertex(point.X, point.Y));
}
TriangleNet.Geometry.Contour parentContour = new TriangleNet.Geometry.Contour(parentVertices);
parentPolygon.Add(parentContour);
foreach (Polyline h in transformedHole)
{
List <TriangleNet.Geometry.Vertex> childVertices = new List <TriangleNet.Geometry.Vertex>();
foreach (Point point in h.IDiscontinuityPoints())
{
childVertices.Add(new TriangleNet.Geometry.Vertex(point.X, point.Y));
}
TriangleNet.Geometry.Contour childContour = new TriangleNet.Geometry.Contour(childVertices);
Point childCentroid = h.PointInRegion();
parentPolygon.Add(childContour, new TriangleNet.Geometry.Point(childCentroid.X, childCentroid.Y));
}
// Triangulate
TriangleNet.Meshing.ConstraintOptions options = new TriangleNet.Meshing.ConstraintOptions()
{
ConformingDelaunay = conformingDelaunay,
};
TriangleNet.Meshing.QualityOptions quality = new TriangleNet.Meshing.QualityOptions()
{
};
TriangleNet.Mesh mesh = (TriangleNet.Mesh)TriangleNet.Geometry.ExtensionMethods.Triangulate(parentPolygon, options, quality);
// Convert triangulations back to BHoM geometry
List <Polyline> translatedPolylines = new List <Polyline>();
foreach (var face in mesh.Triangles)
{
// List points defining the triangle
List <Point> pts = new List <Point>();
pts.Add(BH.Engine.Geometry.Create.Point(face.GetVertex(0).X, face.GetVertex(0).Y));
pts.Add(BH.Engine.Geometry.Create.Point(face.GetVertex(1).X, face.GetVertex(1).Y));
pts.Add(BH.Engine.Geometry.Create.Point(face.GetVertex(2).X, face.GetVertex(2).Y));
pts.Add(pts.First());
translatedPolylines.Add(BH.Engine.Geometry.Create.Polyline(pts));
}
// Translate back to original plane
List <Polyline> meshPolylines = new List <Polyline>();
foreach (Polyline pl in translatedPolylines)
{
TransformMatrix matrixTransposed = transformMatrix.Invert();
Polyline meshPolyline = pl.Translate(-translateVector).Transform(transformMatrix.Invert());
meshPolylines.Add(meshPolyline);
}
return(meshPolylines);
}
