/// <summary>
/// 交点を有するかどうか
/// </summary>
/// <param name="ls"></param>
/// <returns></returns>
public bool Intersects(LineSegment2D ls)
{
double temp = (p2.X - p1.X) * (ls.p2.Y - ls.p1.Y) - (p2.Y - p1.Y) * (ls.p2.X - ls.p1.X);
double temp_r = (ls.p2.Y - ls.p1.Y) * (ls.p1.X - p1.X) - (ls.p2.X - ls.p1.X) * (ls.p1.Y - p1.Y);
double temp_s = (p2.Y - p1.Y) * (ls.p1.X - p1.X) - (p2.X - p1.X) * (ls.p1.Y - p1.Y);
if (temp == 0) //並行
{
if (temp_r != 0)
{
return false;
}
else //同一直線上
{
if (ls.IsPointOnLineSegment(p1) | ls.IsPointOnLineSegment(p2))
{
return true;
}
else
{
return false;
}
}
}
else
{
double r = temp_r / temp;
double s = temp_s / temp;
if ((r < 0) | (1 < r) | (s < 0) | (1 < s))
{
return false;
}
else
{
return true;
}
}
}
/// <summary>
/// 検査点が<c>FigurePath</c>で表された図形パスの内部に存在するかどうか．閉じられた図形パスが存在しない場合にはnullを返す．
/// </summary>
/// <param name="p">検査点</param>
/// <returns></returns>
public bool? IsInside(Point2D p)
{
if (Count >= 3)
{
if ((p.X < min_x) | (p.X > max_x) | (p.Y < min_y) | (p.Y > max_y)) //パス包含長方形の外部
{
return false;
}
else
{
bool temp2 = false;
foreach (LineSegment2D line in lines)
{
temp2 |= line.IsPointOnLineSegment(p);
}
if (temp2) //パス境界上
{
return false;
}
else
{
double size = Math.Sqrt((max_x - min_x) * (max_x - min_x) + (max_y - min_y) * (max_y - min_y));
Random rnd = new Random();
LineSegment2D ray;
bool ray_is_crossing_on_point;
do
{
double theta = rnd.NextDouble() * 2.0 * Math.PI;
ray = new LineSegment2D(p, new Point2D(p.X + size * Math.Cos(theta), p.Y + size * Math.Sin(theta)));
ray_is_crossing_on_point = false;
foreach (Point2D tested_point in points)
{
ray_is_crossing_on_point |= ray.IsPointOnLineSegment(tested_point);
}
}
while (ray_is_crossing_on_point); //パスのノード上を通過することのないレイを選択
int crossing_count = 0;
foreach (LineSegment2D select_ls in lines)
{
if (select_ls.Intersects(ray))
{
crossing_count++;
}
}
return crossing_count % 2 == 0 ? false : true;
}
}
}
else
{
return null;
}
}
