public Pt p1, p2, vect; //vector p1 -> p2
#endregion Fields
#region Constructors
public Edge(Pt p1n, Pt p2n)
{
p1 = p1n;
p2 = p2n;
vect = p2 - p1;
norm = vect.Norm();
}
public double Dist(Pt p)
{
//distance from p to the edge
if (vect.Dot(p - p1) <= 0)
return p.Dist(p1); //from p to p1
if (vect.Dot(p - p2) >= 0)
return p.Dist(p2); //from p to p2
//distance to the line itself
return Math.Abs(-vect.Y * p.X + vect.X * p.Y + p1.X * p2.Y - p1.Y * p2.X) / norm;
}
/// <summary>
/// Dot product of two vectors: O -> this and O -> other
/// a dot b = |a| |b| cos(theta) = ax bx + ax by
/// zero if two vectors run orthogonally
/// </summary>
public double Dot(Pt other)
{
return DoubleUtil.Add(this.X * other.X, this.Y * other.Y);
}
static double get_vector_length(Pt v)
{
return Math.Pow((v.X * v.X) + (v.Y * v.Y), 0.5);
}
/// <summary>
/// Cross(det) product of two vectors: O -> this and O -> other
/// a x b = |a| |b| sin(theta) = ax by - ay bx
/// zero if two vectors run parallelly
/// </summary>
public double Cross(Pt other)
{
return DoubleUtil.Add(this.X * other.Y, -this.Y * other.X);
}
public double Dist(Pt other)
{
return (this - other).Norm();
}
/// <summary>
/// crosssing point of line p1-p2 and q1-q2
/// </summary>
public static Pt Intersect(Pt p1, Pt p2, Pt q1, Pt q2)
{
return p1 + (p2 - p1) * ((q2 - q1).Cross(q1 - p1) / (q2 - q1).Cross(p2 - p1));
}
/// <summary>
/// point q exists on line p1-p2?
/// </summary>
public static bool OnSeg(Pt p1, Pt p2, Pt q)
{
return (p1 - q).Cross(p2 - q) == 0 && (p1 - q).Dot(p2 - q) <= 0;
}
public static bool HasIntersect(Pt p1, Pt p2, Pt q1, Pt q2)
{
if ((p1 - q1).Cross(p2 - q2) == 0)
{
return OnSeg(p1, q1, p2) || OnSeg(p1, q1, q2) || OnSeg(p2, q2, p1) || OnSeg(p2, q2, q1);
}
else
{
var r = Intersect(p1, q1, p2, q2);
return OnSeg(p1, p2, r) && OnSeg(q1, q2, r);
}
}
//ger radian angle of vector A and B
public static double GetAngleOf2Vectors(Pt A, Pt B)
{
double length_A = get_vector_length(A);
double length_B = get_vector_length(B);
double cos_sita = A.Dot(B) / (length_A * length_B);
double sita = Math.Acos(cos_sita);
//degree in 0^180
//sita = sita * 180.0 / PI;
return sita;
}
public static double Dist(Pt v1, Pt v2)
{
return v1.Dist(v2);
}
public static int Ccw(Pt a, Pt b, Pt c)
{
b -= a;
c -= a;
if (b.Cross(c) > 0) return 1; //counter clockwise
if (b.Cross(c) < 0) return -1; //clockwise
if (b.Dot(c) < 0) return 2; //c--a--b on line
if (b.Norm() < c.Norm()) return -2; //a--b--c on line
return 0;
}
public Circle(Pt p, double r)
{
P = p;
R = r;
}