public List <Vector2[]> TriangulateClipperSolution(ClipperLib.PolyTree solution)
{
var tess = new Tess();
tess.NoEmptyPolygons = true;
// Add a contour for each part of the solution tree
ClipperLib.PolyNode node = solution.GetFirst();
while (node != null)
{
// Only interested in closed paths
if (!node.IsOpen)
{
// Add a new countor. Holes are automatically generated.
var vertices = node.Contour.Select(pt => new ContourVertex {
Position = new Vec3 {
X = pt.X, Y = pt.Y, Z = 0
}
}).ToArray();
tess.AddContour(vertices);
}
node = node.GetNext();
}
return(TrianglesFromTessellator(tess));
}
private static void ClipperPolyTreeToPolygonListRecursively(ClipperLib.PolyNode node, HashSet <ClipperLib.IntPoint> sharpPoints, HashSet <ClipperLib.IntPoint> allPoints, List <PolygonClosedD2D> polygonList, IDictionary <ClipperLib.PolyNode, PolygonClosedD2D> dictClipperNodeToNode)
{
if (node.Contour != null && node.Contour.Count != 0)
{
var pointsInThisPolygon = node.Contour.Select(clipperPt => new PointD2D(clipperPt.X / 65536.0, clipperPt.Y / 65536.0));
var sharpPointsInThisPolygon = node.Contour.Where(clipperPt => sharpPoints.Contains(clipperPt)).Select(clipperPt => new PointD2D(clipperPt.X / 65536.0, clipperPt.Y / 65536.0));
var polygon = new PolygonClosedD2D(pointsInThisPolygon.ToArray(), new HashSet <PointD2D>(sharpPointsInThisPolygon))
{
IsHole = node.IsHole
};
polygonList.Add(polygon);
if (node.IsHole)
{
polygon.Parent = dictClipperNodeToNode[node.Parent];
}
dictClipperNodeToNode.Add(node, polygon);
}
if (0 != node.ChildCount)
{
foreach (var childNode in node.Childs)
{
ClipperPolyTreeToPolygonListRecursively(childNode, sharpPoints, allPoints, polygonList, dictClipperNodeToNode);
}
}
}
private List <Poly2Tri.DelaunayTriangle> GetTriangleListFromClipperSolution(ClipperLib.PolyTree solution)
{
Func <ClipperLib.IntPoint, Poly2Tri.PolygonPoint> xfToPolygonPoint = (p) => new Poly2Tri.PolygonPoint(p.X, p.Y);
Poly2Tri.PolygonSet polygonSet = new Poly2Tri.PolygonSet();
ClipperLib.PolyNode node = solution.GetFirst();
while (node != null)
{
// Only interested in closed paths
if (!node.IsOpen)
{
if (node.IsHole)
{
if (polygonSet.Polygons.Count() > 0)
{
// Add hole to last polygon entered
var polyPoints = node.Contour.Select(xfToPolygonPoint).ToArray();
Poly2Tri.Polygon hole = new Poly2Tri.Polygon(polyPoints);
Poly2Tri.Polygon polygon = polygonSet.Polygons.Last();
polygon.AddHole(hole);
}
}
else
{
// Add a new polygon to the set
var polyPoints = node.Contour.Select(xfToPolygonPoint).ToList();
Poly2Tri.Polygon polygon = new Poly2Tri.Polygon(polyPoints);
polygonSet.Add(polygon);
}
}
node = node.GetNext();
}
// Now triangulate the whole set
Poly2Tri.P2T.Triangulate(polygonSet);
// Combine all the triangles into one list
List <Poly2Tri.DelaunayTriangle> triangles = new List <Poly2Tri.DelaunayTriangle>();
foreach (var polygon in polygonSet.Polygons)
{
triangles.AddRange(polygon.Triangles);
}
return(triangles);
}
private void ExtractOutlines(ClipperLib.PolyNode tree, List <IShape> shapes)
{
if (tree.Contour.Any())
{
// convert the Clipper Contour from scaled ints back down to the origional size (this is going to be lossy but not significantly)
var pointCount = tree.Contour.Count;
var vectors = new Vector2[pointCount];
for (var i = 0; i < pointCount; i++)
{
var p = tree.Contour[i];
vectors[i] = new Vector2(p.X, p.Y) / ClipperScaleFactor;
}
var polygon = new Polygon(new LinearLineSegment(vectors));
shapes.Add(polygon);
}
foreach (var c in tree.Childs)
{
this.ExtractOutlines(c, shapes);
}
}
public List <PointF[]> Triangulate(ClipperLib.PolyTree solution)
{
List <PointF[]> triangles = new List <PointF[]>();
var tess = new LibTessDotNet.Tess();
tess.NoEmptyPolygons = true;
// Transformation function from ClipperLip Point to LibTess contour vertex
Func <ClipperLib.IntPoint, LibTessDotNet.ContourVertex> xfToContourVertex = (p) => new LibTessDotNet.ContourVertex()
{
Position = new LibTessDotNet.Vec3 {
X = p.X, Y = p.Y, Z = 0
}
};
// Add a contour for each part of the solution tree
ClipperLib.PolyNode node = solution.GetFirst();
while (node != null)
{
// Only interested in closed paths
if (!node.IsOpen)
{
// Add a new countor. Holes are automatically generated.
var vertices = node.Contour.Select(xfToContourVertex).ToArray();
tess.AddContour(vertices);
}
node = node.GetNext();
}
// Do the tessellation
tess.Tessellate(LibTessDotNet.WindingRule.EvenOdd, LibTessDotNet.ElementType.Polygons, 3);
// Extract the triangles
int numTriangles = tess.ElementCount;
for (int i = 0; i < numTriangles; i++)
{
var v0 = tess.Vertices[tess.Elements[i * 3 + 0]].Position;
var v1 = tess.Vertices[tess.Elements[i * 3 + 1]].Position;
var v2 = tess.Vertices[tess.Elements[i * 3 + 2]].Position;
List <PointF> triangle = new List <PointF>()
{
new PointF(v0.X, v0.Y),
new PointF(v1.X, v1.Y),
new PointF(v2.X, v2.Y),
};
// Assre each triangle needs to be CCW
float cross = Geometry.Math.Cross(triangle[0], triangle[1], triangle[2]);
if (cross > 0)
{
triangle.Reverse();
}
triangles.Add(triangle.ToArray());
}
return(triangles);
}
