public static List <Vector> GetConvexHull(this PointString poly)
{
var points = new List <Vector>();
var collection = new List <Vector>();
int num = 0;
var source = poly.Points.ToList();
source.Sort((p1, p2) => (p1.X - p2.X == 0) ? (int)(p1.Y - p2.Y) : (int)(p1.X - p2.X));
points.Add(source[0]);
points.Add(source[1]);
for (num = 2; num <= (source.Count - 1); num++)
{
points.Add(source[num]);
while ((points.Count >= 3) && !IsTurnRight(points[points.Count - 3], points[points.Count - 2], points[points.Count - 1]))
{
points.RemoveAt(points.Count - 2);
}
}
collection.Add(source[source.Count - 1]);
collection.Add(source[source.Count - 2]);
for (num = source.Count - 2; num >= 0; num--)
{
collection.Add(source[num]);
while ((collection.Count >= 3) && !IsTurnRight(collection[collection.Count - 3], collection[collection.Count - 2], collection[collection.Count - 1]))
{
collection.RemoveAt(collection.Count - 2);
}
}
collection.RemoveAt(collection.Count - 1);
collection.RemoveAt(0);
points.AddRange(collection);
return(points);
}
public static double DistToPoint(this PointString poly, Vector p, int divs) // newly 20130523 近似法
{
var points = poly.Points;
double delta = (double)(points.Count - 1) / divs;
var pts = Enumerable.Range(0, divs + 1).Select(i => poly.Lerp(i * delta)).ToList();
return(pts.Min(pt => pt.Dist(p)));
}
public static LineSeg GetSegAt(this PointString poly, int i)
{
var points = poly.Points;
if (i < 0)
{
i = 0;
}
else if (i > points.Count - 1)
{
i = points.Count - 1;
}
int j = i >= points.Count - 1 ? 0 : i + 1;
return(new LineSeg(points[i], points[j]));
}
public static PointString Offset(this PointString poly, double offset)
{
var points0 = poly.Points;
var points1 = new List <Vector>();
if (points0.Count <= 0)
{
//return null;
}
else if (points0.Count == 1)
{
var pt = new Vector(points0[0].X + offset, points0[0].Y);
points1.Add(pt);
}
else if (points0.Count == 2)
{
points1 = GetOffsetSeg(points0[0], points0[1], offset);
}
else
{
var pt1 = GetOffsetSeg(points0[0], points0[1], offset)[0];
points1.Add(pt1);
for (int count = 1; count <= points0.Count - 1; count++)
{
if (count == points0.Count - 1)
{
var pt = GetOffsetSeg(points0[count - 1], points0[count], offset)[1];
points1.Add(pt);
}
else
{
var p10 = GetOffsetSeg(points0[count - 1], points0[count], offset)[0];
var p11 = GetOffsetSeg(points0[count - 1], points0[count], offset)[1];
var p20 = GetOffsetSeg(points0[count], points0[count + 1], offset)[0];
var p21 = GetOffsetSeg(points0[count], points0[count + 1], offset)[1];
var d0 = new Vector(p11.X - p10.X, p11.Y - p10.Y);
var d1 = new Vector(p20.X - p21.X, p20.Y - p21.Y);
points1.Add(GetIntersection(p10, p21, d0, d1));
}
}
}
return(new PointString(points1));
}
public static void ReducePoints(this PointString poly, double epsilon)
{
var points = poly.Points;
var cleanList = new List <int>();
int j = 0;
for (int i = 1; i < points.Count; i++)
{
if (points[i].Dist(points[j]) < epsilon)
{
cleanList.Add(i);
}
else
{
j = i;
}
}
cleanList.Reverse();
cleanList.ForEach(x => points.RemoveAt(x));
}
public static PointString GetSubPoly(this PointString poly, double start, double end)
{
var points = poly.Points;
start = (start < 0) ? 0 : start;
end = (end > points.Count - 1) ? (points.Count - 1) : end;
var pts = new List <Vector>();
double a = Math.Ceiling(start);
double b = Math.Floor(end);
for (int i = (int)a; i <= (int)b; i++)
{
pts.Add(points[i]);
}
if (start < a)
{
pts.Insert(0, poly.Lerp(start));
}
if (end > b)
{
pts.Add(poly.Lerp(end));
}
return(new PointString(pts));
}
public static double DistToPoint(this PointString poly, Vector p)
{
Vector foot;
return(DistToPoint(poly, p, out foot));
}
public static double DistToPoint(this PointString poly, Vector p, out Vector footPos)
{
var points = poly.Points;
double minDist = points.Min(x => x.Dist(p));
var minPoint = points.First(x => x.Dist(p) == minDist);
if (minPoint.Equals(points.First()))
{
LineSeg seg1 = new LineSeg(points[0], points[1]);
LineSegPointRelation relation1 = new LineSegPointRelation(seg1, p);
if (relation1.Inner)
{
footPos = relation1.Foot;
return(relation1.Dist);
}
else
{
footPos = minPoint;
return(minDist);
}
}
else if (minPoint.Equals(points.Last()))
{
int n = points.Count;
LineSeg seg1 = new LineSeg(points[n - 2], points[n - 1]);
LineSegPointRelation relation1 = new LineSegPointRelation(seg1, p);
if (relation1.Inner)
{
footPos = relation1.Foot;
return(relation1.Dist);
}
else
{
footPos = minPoint;
return(minDist);
}
}
else
{
int index = points.IndexOf(minPoint);
LineSeg seg1 = new LineSeg(points[index - 1], points[index]);
LineSeg seg2 = new LineSeg(points[index + 1], points[index]);
LineSegPointRelation relation1 = new LineSegPointRelation(seg1, p);
LineSegPointRelation relation2 = new LineSegPointRelation(seg2, p);
if (relation1.Inner)
{
footPos = relation1.Foot;
return(relation1.Dist);
}
else if (relation2.Inner)
{
footPos = relation1.Foot;
return(relation2.Dist);
}
else
{
footPos = minPoint;
return(minDist);
}
}
}