public Polygon Clone()
{
Polygon g = new Polygon();
for (int k=0;k< contours.Count;k++) {
g.AddContour(contours[k].Clone());
}
return g;
}
public Polygon ToPolygon()
{
// Check for empty result
if ((closedPolygons.Count == 0 ||
(closedPolygons.Count == 1 && closedPolygons[0].pointList.Count == 0)) &&
(openPolygons.Count == 0 ||
(openPolygons.Count == 1 && openPolygons[0].pointList.Count == 0))) {
return null;
}
Polygon polygon = new Polygon ();
foreach (PointChain pointChain in closedPolygons) {
Contour c = new Contour ();
c.AddRange (pointChain.pointList);
polygon.AddContour (c);
}
FixOrientation(polygon);
return polygon;
}
public void Compute(PolygonOp operation)
{
subject = ComputeInternal(operation);
}
// public PolygonClipper(Region regionSubject, Region regionClipping) {
// // Setup subject and clipping polygons
// this.regionSubject = regionSubject;
// subject = new Polygon();
// Contour scont = new Contour();
// scont.AddRange(regionSubject.points);
// subject.AddContour(scont);
// SetClippingRegion(regionClipping);
// }
//
// public void SetClippingRegion(Region regionClipping) {
// clipping = new Polygon();
// Contour ccont = new Contour();
// ccont.AddRange(regionClipping.points);
// clipping.AddContour(ccont);
// }
public PolygonClipper(Polygon subject, Polygon clipping)
{
this.subject = subject;
this.clipping = clipping;
}
/// <summary>
/// Since polygons from countries and cells are not perfectly aligned in all cases, this method will take the largest contour and assume this is the resulting polygon
/// (even if it's not closed...)
/// </summary>
public Polygon ToPolygonFromLargestLineStrip()
{
// Check for empty result
if ((closedPolygons.Count == 0 ||
(closedPolygons.Count == 1 && closedPolygons[0].pointList.Count == 0)) &&
(openPolygons.Count == 0 ||
(openPolygons.Count == 1 && openPolygons[0].pointList.Count == 0))) {
return null;
}
// Get the largest contour (open or closed)
int maxPoints=-1;
PointChain largestPointChain = null;
foreach (PointChain pointChain in closedPolygons) {
if (pointChain.pointList.Count>maxPoints) {
maxPoints = pointChain.pointList.Count;
largestPointChain = pointChain;
}
}
foreach (PointChain pointChain in openPolygons) {
if (pointChain.pointList.Count>maxPoints) {
maxPoints = pointChain.pointList.Count;
largestPointChain = pointChain;
}
}
// ... and create a new polygon of that
if (maxPoints<0) return null;
Polygon polygon = new Polygon ();
Contour c = new Contour ();
c.AddRange (largestPointChain.pointList);
polygon.AddContour (c);
FixOrientation(polygon);
return polygon;
}
// orientation2D_Polygon(): test the orientation of a simple 2D polygon
// Input: Point* V = an array of n+1 vertex points with V[n]=V[0]
// Return: >0 for counterclockwise
// =0 for none (degenerate)
// <0 for clockwise
// Note: this algorithm is faster than computing the signed area.
// From http://geomalgorithms.com/a01-_area.html#orientation2D_Polygon()
double[] Orientation(Polygon V)
{
// first find rightmost lowest vertex of the polygon
double[] ou = new double[V.contours.Count];
for(int j=0;j<V.contours.Count;j++) {
Contour r = V.contours[j];
int rmin = 0;
double xmin = r.points[0].x;
double ymin = r.points[0].y;
for(int i=0;i<r.points.Count;i++) {
Point p = r.points[i];
if (p.y > ymin) {
continue;
} else if (p.y == ymin) { // just as low
if (p.x < xmin) { // and to left
continue;
}
}
rmin = i; // a new rightmost lowest vertex
xmin = p.x;
ymin = p.y;
}
// test orientation at the rmin vertex
// ccw <=> the edge leaving V[rmin] is left of the entering edge
if (rmin == 0 || rmin == r.points.Count-1) {
ou[j] = isLeft(r.points[r.points.Count-2], r.points[0], r.points[1]);
} else {
ou[j] = isLeft(r.points[rmin-1], r.points[rmin], r.points[rmin+1]);
}
}
return ou;
}
// Change the winding direction of the outer and inner
// rings so the outer ring is counter-clockwise and
// nesting rings alternate directions.
void FixOrientation(Polygon g)
{
Polygon p = g; //.(geom.Polygon)
double[] o = Orientation(p);
for (int i=0;i<p.contours.Count;i++) {
Contour inner = p.contours[i];
int numInside = 0;
for (int j=0;j<p.contours.Count;j++) {
Contour outer = p.contours[j];
if (i != j) {
if (PolyInPoly(outer, inner)) {
numInside++;
}
}
}
if (numInside % 2 == 1 && o[i] > 0) {
ReversePolygon(inner.points);
} else if (numInside % 2 == 0 && o[i] < 0) {
ReversePolygon(inner.points);
}
}
}