public static MyPoint[] convexhull(MyPoint[] pts)
{
// Отсортировать точки по увеличению (x, y)
int N = pts.Length;
Polysort.Quicksort <MyPoint>(pts);
MyPoint left = pts[0], right = pts[N - 1];
// Разделить на список нижних граней и верхних граней
CDLL <MyPoint> lower = new CDLL <MyPoint>(left), upper = new CDLL <MyPoint>(left);
for (int i = 0; i < N; i++)
{
double det = MyPoint.Area2(left, right, pts[i]);
if (det > 0)
{
upper = upper.Append(new CDLL <MyPoint>(pts[i]));
}
else if (det < 0)
{
lower = lower.Prepend(new CDLL <MyPoint>(pts[i]));
}
}
lower = lower.Prepend(new CDLL <MyPoint>(right));
upper = upper.Append(new CDLL <MyPoint>(right)).Next;
// Устранить точки не на многоуголнике
eliminate(lower);
eliminate(upper);
// Устранить повторяющиеся точки
try
{
if (lower.Prev.val.Equals(upper.val))
{
lower.Prev.Delete();
}
if (upper.Prev.val.Equals(lower.val))
{
upper.Prev.Delete();
}
}
catch
{
// DO NOTHING!!! JUST SKIP ERROR
}
// Соединяем нижние и верхние грани
MyPoint[] res = new MyPoint[lower.Size() + upper.Size()];
lower.CopyInto(res, 0);
upper.CopyInto(res, lower.Size());
return(res);
}
public static Vec2d[] GetConvexHull(Vec2d[] pts)
{
// Sort points lexicographically by increasing (x, y)
int N = pts.Length;
quicksort(pts);
Vec2d left = pts[0], right = pts[N - 1];
// Partition into lower hull and upper hull
CDLL <Vec2d> lower = new CDLL <Vec2d>(left), upper = new CDLL <Vec2d>(left);
for (int i = 0; i < N; i++)
{
double det = area2(left, right, pts[i]);
if (det > 0)
{
upper = upper.Append(new CDLL <Vec2d>(pts[i]));
}
else if (det < 0)
{
lower = lower.Prepend(new CDLL <Vec2d>(pts[i]));
}
}
lower = lower.Prepend(new CDLL <Vec2d>(right));
upper = upper.Append(new CDLL <Vec2d>(right)).Next;
// Eliminate points not on the hull
eliminate(lower);
eliminate(upper);
// Eliminate duplicate endpoints
if (lower.Prev.val.Equals(upper.val))
{
lower.Prev.Delete();
}
if (upper.Prev.val.Equals(lower.val))
{
upper.Prev.Delete();
}
// Join the lower and upper hull
Vec2d[] res = new Vec2d[lower.Size() + upper.Size()];
lower.CopyInto(res, 0);
upper.CopyInto(res, lower.Size());
return(res);
}
