//求散点集的凸包
public IPositionSet ConvexHull(IPositionSet ps)
{
IPosition p1 = null;
IPosition p2 = null;
PositionSetEdit_ImplementByICollectionTemplate rest = new PositionSetEdit_ImplementByICollectionTemplate();
//找到最低点
/*
* p1 = pts[0];
* for (int i = 1; i < pts.Length; i++)
* {
* if (pts[i].Y < p1.Y || ( pts[i].Y == p1.Y && pts[i].X < p1.X) )
* {
* rest.Add(p1);
* p1 = pts[i];
* }
* else
* rest.Add(pts[i]);
* }
* */
ps.InitToTraverseSet();
if (ps.NextPosition())
{
p1 = ps.GetPosition();
}
while (ps.NextPosition())
{
p2 = ps.GetPosition();
if (p2.GetY() < p1.GetY() || (p2.GetY() == p1.GetY() && p2.GetX() < p1.GetX()))
{
rest.AddPosition(p1);
p1 = p2;
}
else
{
rest.AddPosition(p2);
}
}
rest.InitToTraverseSet();
//找到与最低点成角最小的点
/*
* int p2_i = 0;
* double p2_angle = getAngle(rest[0], p1);
* for (int i = 1; i < rest.Count; i++)
* {
* double angle_t = getAngle(rest[i], p1);
* if (angle_t < p2_angle || (angle_t == p2_angle && getDistance(p1, rest[i]) > getDistance(p1, rest[p2_i])) )
* {
* p2_i = i;
* p2_angle = angle_t;
* }
* }
* p2 = rest[p2_i];
* rest.RemoveAt(p2_i);
* */
ps = rest;
rest = new PositionSetEdit_ImplementByICollectionTemplate();
ps.InitToTraverseSet();
if (ps.NextPosition())
{
p2 = ps.GetPosition();
}
double p2_angle = getAngle(p2, p1);
while (ps.NextPosition())
{
IPosition pt = ps.GetPosition();
double angle_t = getAngle(pt, p1);
if (angle_t < p2_angle || (angle_t == p2_angle && getDistance(p1, pt) > getDistance(p1, p2)))
{
rest.AddPosition(p2);
p2 = pt;
p2_angle = angle_t;
}
else
{
rest.AddPosition(pt);
}
}
//求解剩余点
IPositionSet subResult = solveHelp(p1, p2, rest);
//组合成凸包
PositionSetEdit_ImplementByICollectionTemplate result = new PositionSetEdit_ImplementByICollectionTemplate();
result.AddPosition(p1);
/*
* foreach (Point p in subResult)
* result.Add(p);
* */
subResult.InitToTraverseSet();
while (subResult.NextPosition())
{
result.AddPosition(subResult.GetPosition());
}
result.AddPosition(p2);
return(result);
}
//求散点子集的凸包
private IPositionSet solveHelp(IPosition p1, IPosition p2, IPositionSet ps)
{
//求离p1，p2最远的点
ps.InitToTraverseSet();
if (!ps.NextPosition())
{
return(ps);
}
IPosition p3 = ps.GetPosition();
double p3_h = getH(p1, p2, p3);
PositionSetEdit_ImplementByICollectionTemplate rest = new PositionSetEdit_ImplementByICollectionTemplate();
while (ps.NextPosition())
{
IPosition pt = ps.GetPosition();
double pt_h = getH(p1, p2, pt);
if (pt_h > p3_h)
{
rest.AddPosition(p3);
p3 = pt;
p3_h = pt_h;
}
else
{
rest.AddPosition(pt);
}
}
//把散点分成几部分
PositionSetEdit_ImplementByICollectionTemplate leftpart = new PositionSetEdit_ImplementByICollectionTemplate();
PositionSetEdit_ImplementByICollectionTemplate rightpart = new PositionSetEdit_ImplementByICollectionTemplate();
PositionSetEdit_ImplementByICollectionTemplate p1set = new PositionSetEdit_ImplementByICollectionTemplate();
PositionSetEdit_ImplementByICollectionTemplate p2set = new PositionSetEdit_ImplementByICollectionTemplate();
ps = rest;
IPosition p11 = new Position_Point(2 * p2.GetX() - p1.GetX(), 2 * p2.GetY() - p1.GetY()); //p1关于p2的对称点
double leftangle = getAngle(p1, p2, p3);
double rightangle = getAngle(p2, p11, p3);
ps.InitToTraverseSet();
while (ps.NextPosition())
{
IPosition p = ps.GetPosition();
if (p.GetX() == p1.GetX() && p.GetY() == p1.GetY())
{
p1set.AddPosition(p);
}
else if (p.GetX() == p2.GetX() && p.GetY() == p2.GetY())
{
p2set.AddPosition(p);
}
else if (p.GetX() == p3.GetX() && p.GetY() == p3.GetY())
{
leftpart.AddPosition(p);
}
else
{
double a = getAngle(p1, p2, p);
if (a > leftangle)
{
leftpart.AddPosition(p);
}
a = getAngle(p2, p11, p);
if (a < rightangle)
{
rightpart.AddPosition(p);
}
}
}
//对子集求解
IPositionSet subResult1 = solveHelp(p1, p3, leftpart);
IPositionSet subResult2 = solveHelp(p3, p2, rightpart);
//合并各部分解
PositionSetEdit_ImplementByICollectionTemplate result = new PositionSetEdit_ImplementByICollectionTemplate();
p1set.InitToTraverseSet();
while (p1set.NextPosition())
{
result.AddPosition(p1set.GetPosition());
}
subResult1.InitToTraverseSet();
while (subResult1.NextPosition())
{
result.AddPosition(subResult1.GetPosition());
}
result.AddPosition(p3);
subResult2.InitToTraverseSet();
while (subResult2.NextPosition())
{
result.AddPosition(subResult2.GetPosition());
}
p2set.InitToTraverseSet();
while (p2set.NextPosition())
{
result.AddPosition(p2set.GetPosition());
}
return(result);
}
private void button1_Click(object sender, EventArgs e)
{
IConvexHullEngine convexhull;
int n;
switch (comboBox1.SelectedIndex)
{
case 0:
convexhull = new GrahamScan();
break;
case 1:
//convexhull = new QuickHull();
convexhull = new M2M_CH();
break;
default:
return;
}
try
{
n = Int32.Parse(textBox1.Text);
}
catch (Exception)
{
return;
}
//Point[] ps = new Point[n];
PositionSetEdit_ImplementByICollectionTemplate ps = new PositionSetEdit_ImplementByICollectionTemplate();
Random r = new Random(DateTime.Now.Millisecond);
//if (true)
{
int minx = (int)(pb.Width * 0.05);
int miny = (int)(pb.Height * 0.05);
for (int i = 0; i < n; i++)
{
int x = r.Next(minx, pb.Width - minx);
int y = r.Next(miny, pb.Height - miny);
//ps[i] = new Point(x, y);
ps.AddPosition(new Position_Point(x, y));
System.Console.Write(x);
System.Console.Write(",");
System.Console.Write(y);
System.Console.WriteLine(",");
}
System.Console.WriteLine();
}
//else
//{
// ps = testData();
//}
IPositionSet convexPoints = convexhull.ConvexHull(ps);
pb.Image = new Bitmap(pb.Width, pb.Height);
Graphics g = Graphics.FromImage(pb.Image);
convexPoints.InitToTraverseSet();
g.Clear(Color.White);
/*
* for (int i = 0; i < ps.Length; i++)
* {
* g.FillEllipse(Brushes.Black, ps[i].X - 2, pb.Height - ps[i].Y - 2, 4, 4);
* g.DrawString("(" + ps[i].X + "," + ps[i].Y + ")", Font, Brushes.Blue, ps[i].X, pb.Height - ps[i].Y);
* }
* for (int i = 0; i < convexPoints.Length; i++)
* {
* if (i != convexPoints.Length - 1)
* g.DrawLine(new Pen(Color.Green), new PointF(convexPoints[i].X, pb.Height - convexPoints[i].Y), new PointF(convexPoints[i + 1].X, pb.Height - convexPoints[i + 1].Y));
* else
* {
* g.DrawLine(new Pen(Color.Green), new PointF(convexPoints[i].X, pb.Height - convexPoints[i].Y), new PointF(convexPoints[0].X, pb.Height - convexPoints[0].Y));
* }
* }
* */
ps.InitToTraverseSet();
IPosition p = ps.GetPosition();
while (p != null)
{
g.FillEllipse(Brushes.Black, p.GetX() - 2, pb.Height - p.GetY() - 2, 4, 4);
g.DrawString("(" + p.GetX() + "," + p.GetY() + ")", Font, Brushes.Blue, p.GetX(), pb.Height - p.GetY());
p = ps.GetPosition();
}
IPosition p1 = convexPoints.GetPosition();
IPosition p2 = convexPoints.GetPosition();
while (p2 != null)
{
g.DrawLine(new Pen(Color.Green), new PointF(p1.GetX(), pb.Height - p1.GetY()), new PointF(p2.GetX(), pb.Height - p2.GetY()));
p1 = p2;
p2 = convexPoints.GetPosition();
}
convexPoints.InitToTraverseSet();
p2 = convexPoints.GetPosition();
g.DrawLine(new Pen(Color.Green), new PointF(p1.GetX(), pb.Height - p1.GetY()), new PointF(p2.GetX(), pb.Height - p2.GetY()));
}