public List <Point> GetHull()
{
if (hullRoot != null)
{
List <Point> leftHullList = hullRoot.GetConvexHull(true).GetArray();
List <Point> rightHullList = hullRoot.GetConvexHull(false).GetArray();
rightHullList.Reverse();
int beginRight = 0;
int endRight = rightHullList.Count;
while (beginRight < leftHullList.Count &&
beginRight < rightHullList.Count &&
leftHullList[leftHullList.Count - beginRight - 1].CompareTo(rightHullList[beginRight]) == 0)
{
++beginRight;
}
while (rightHullList.Count - endRight < leftHullList.Count &&
endRight >= 0 &&
leftHullList[rightHullList.Count - endRight].CompareTo(rightHullList[endRight - 1]) == 0)
{
--endRight;
}
if (endRight > beginRight)
{
leftHullList.AddRange(rightHullList.GetRange(beginRight, endRight - beginRight));
}
return(leftHullList);
}
return(new List <Point>());
}
private static void pushSubHullDown(RedBlackNode current, bool isLeftHalf)
{
if (current != null && !current.IsLeaf && current.GetConvexHull(isLeftHalf) != null)
{
Treap <Point> leftHalf;
Treap <Point> rightHalf;
Treap <Point> .SplitBySize(current.GetConvexHull(isLeftHalf), current.GeLowerSubHullSize(isLeftHalf), out leftHalf, out rightHalf);
current.Left.SetConvexHull(isLeftHalf, Treap <Point> .Merge(leftHalf, current.Left.GetConvexHull(isLeftHalf)));
current.Right.SetConvexHull(isLeftHalf, Treap <Point> .Merge(current.Right.GetConvexHull(isLeftHalf), rightHalf));
current.SetConvexHull(isLeftHalf, null);
}
}
private static void recount(RedBlackNode current, bool isLeftHalf)
{
if (current != null && current.Left != null && current.Right != null && current.GetConvexHull(isLeftHalf) == null)
{
current.MaxPoint = Utils.Max(current.Left.MaxPoint, current.Right.MaxPoint);
Treap <Point> lowerCurrent = current.Left.GetConvexHull(isLeftHalf);
Treap <Point> upperCurrent = current.Right.GetConvexHull(isLeftHalf);
Point loweCurrentPoint = lowerCurrent.Key;
Point upperCurrentPoint = upperCurrent.Key;
double mediumY = (lowerCurrent.MaxElement.Y + upperCurrent.MinElement.Y) / 2;
int toCutFromLowerHull = Treap <Point> .GetSize(lowerCurrent?.Left) + 1;
int toLeaveInUpperHull = Treap <Point> .GetSize(upperCurrent?.Left) + 1;
bool bridgeFound = false;
while (!bridgeFound)
{
Point lowerPrevPoint = lowerCurrent?.Left != null ? lowerCurrent.Left.MaxElement : null;
Point lowerNextPoint = lowerCurrent?.Right != null ? lowerCurrent.Right.MinElement : null;
Point upperPrevPoint = upperCurrent?.Left != null ? upperCurrent.Left.MaxElement : null;
Point upperNextPoint = upperCurrent?.Right != null ? upperCurrent.Right.MinElement : null;
bridgeFound = makeDecisionAboutRotation(ref lowerCurrent, ref loweCurrentPoint, lowerPrevPoint, lowerNextPoint, ref toCutFromLowerHull,
ref upperCurrent, ref upperCurrentPoint, upperPrevPoint, upperNextPoint, ref toLeaveInUpperHull,
mediumY, isLeftHalf);
}
// we want to have top point in right treap after split
--toLeaveInUpperHull;
Treap <Point> leftPartOfLowerHull;
Treap <Point> rightPartOfLowerHull;
Treap <Point> leftPartOfUpperHull;
Treap <Point> rightPartOfUpperHull;
if (loweCurrentPoint.Y == upperCurrentPoint.Y)
{
if ((loweCurrentPoint.X < upperCurrentPoint.X && isLeftHalf) ||
(loweCurrentPoint.X > upperCurrentPoint.X && !isLeftHalf))
{
++toLeaveInUpperHull;
}
else if ((loweCurrentPoint.X > upperCurrentPoint.X && isLeftHalf) ||
(loweCurrentPoint.X < upperCurrentPoint.X && !isLeftHalf))
{
--toCutFromLowerHull;
}
else
{
toLeaveInUpperHull++;
}
}
current.SetLowerSubHullSize(isLeftHalf, toCutFromLowerHull);
Treap <Point> .SplitBySize(current.Left.GetConvexHull(isLeftHalf), toCutFromLowerHull, out leftPartOfLowerHull, out rightPartOfLowerHull);
Treap <Point> .SplitBySize(current.Right.GetConvexHull(isLeftHalf), toLeaveInUpperHull, out leftPartOfUpperHull, out rightPartOfUpperHull);
current.SetConvexHull(isLeftHalf, Treap <Point> .Merge(leftPartOfLowerHull, rightPartOfUpperHull));
current.Left.SetConvexHull(isLeftHalf, rightPartOfLowerHull);
current.Right.SetConvexHull(isLeftHalf, leftPartOfUpperHull);
}
}
