public static Polygon Create(IPointCloud pointCloud, double searchRange, int kNearestCount)
{
var result = new Polygon();
var currPoint = pointCloud.QuadTree.GetLowestYPoint();
result.Points.Add(currPoint);
//Uno a sinistra così può calcolare l'angolo in modo uniforme
var prevPoint = new DblPoint2(currPoint.x - 1, currPoint.y);
while (true)
{
var nextPoint = GetNextPoint(pointCloud, result, prevPoint, currPoint, result.Points.Count < 3 ? result.Points : result.Points.Skip(1),
searchRange, kNearestCount);
if (nextPoint == result.Points[0])
break;
result.Points.Add(nextPoint);
prevPoint = currPoint;
currPoint = nextPoint;
}
return result;
}
private static DblPoint2 GetNextPoint(IPointCloud pointCloud, Polygon partialResult, DblPoint2 prevPoint, DblPoint2 currPoint, IEnumerable<DblPoint2> excludedPoints,
double searchRange, int kNearestCount)
{
while (true)
{
var kNearest = new List<DblPoint2>();
var actualkNearestCount = kNearestCount;
while (true)
{
pointCloud.QuadTree.GetPointsInsideCircle(currPoint, 1000000.0, kNearest);
kNearest.RemoveAll((x) => excludedPoints.Contains(x));
if (kNearest.Count < actualkNearestCount && kNearest.Count != (pointCloud.Points.Count() - excludedPoints.Count()))
{
actualkNearestCount++;
kNearest.Clear();
}
else if (kNearest.Count > 3)
{
kNearest = (from k in kNearest
orderby (k - currPoint).Length2 ascending
select k).Take(actualkNearestCount).ToList();
break;
}
else
break;
}
var kNearestOrderedByAngle = (from k in kNearest
orderby (prevPoint - currPoint).CWAngleTo(k - currPoint) descending
select k).ToList();
//Rimuovi tutti quelli che intersecano il poligono corrente
var kNearestOrderedByAngleNotIntersecting = (from k in kNearestOrderedByAngle
where !IntersectAnyPolygonEdgeExceptLast(partialResult, currPoint, k)
select k).ToList();
if (kNearestOrderedByAngleNotIntersecting.Count > 0)
return kNearestOrderedByAngleNotIntersecting.First();
}
}
private static Boolean IntersectAnyPolygonEdgeExceptLast(Polygon polygon, DblPoint2 p1, DblPoint2 p2)
{
var s12 = new Segment(p1, p2);
for (var i = 0; i < polygon.Points.Count - 1; i++)
{
var result = new Segment(polygon.Points[i], polygon.Points[i + 1]).Intersect(s12);
if (result.IsIntersection)
return true;
}
return false;
}