Intersection Of Two Lines - CSharp System

CSharp examples for System:Math Geometry

  1. HOME
  2. CSharp
  3. System
  4. Math Geometry

Description

Intersection Of Two Lines

Demo Code


using System.Drawing;
using System;//w w w  .j av a2 s.c om

public class Main{
        public static bool IntersectionOfTwoLines(Point a, Point b, Point c, Point d, ref Point intersect)
        {
            double r, s;

            double denominator = (b.X - a.X) * (d.Y - c.Y) - (b.Y - a.Y) * (d.X - c.X);

            // If the denominator in above is zero, AB & CD are colinear
            if (denominator == 0)
                return false;

            double numeratorR = (a.Y - c.Y) * (d.X - c.X) - (a.X - c.X) * (d.Y - c.Y);
            //  If the numerator above is also zero, AB & CD are collinear.
            //  If they are collinear, then the segments may be projected to the x- 
            //  or y-axis, and overlap of the projected intervals checked.

            r = numeratorR / denominator;

            double numeratorS = (a.Y - c.Y) * (b.X - a.X) - (a.X - c.X) * (b.Y - a.Y);

            s = numeratorS / denominator;

            //  If 0<=r<=1 & 0<=s<=1, intersection exists
            //  r<0 or r>1 or s<0 or s>1 line segments do not intersect
            if (r < 0 || r > 1 || s < 0 || s > 1)
                return false;

            ///*
            //    Note:
            //    If the intersection point of the 2 lines are needed (lines in this
            //    context mean infinite lines) regardless whether the two line
            //    segments intersect, then
            //
            //        If r>1, P is located on extension of AB
            //        If r<0, P is located on extension of BA
            //        If s>1, P is located on extension of CD
            //        If s<0, P is located on extension of DC
            //*/

            // Find intersection point
            intersect.X = (int)(a.X + (r * (b.X - a.X)));
            intersect.Y = (int)(a.Y + (r * (b.Y - a.Y)));

            return true;
        }
}

Related Tutorials