// line 1: (x0,y0)-(x1,y1), line 2: (x2,y2)-(x3,y3)
// intersection point: (outx, outy)
// return value: false (no intersection point), true (1 intersection point)
//
public static bool LineIntersectWithLine(
double x0, double y0, double x1, double y1,
double x2, double y2, double x3, double y3,
ref double outx, ref double outy,
ExtendOption option)
{
double a11 = x3 - x2;
double a12 = x0 - x1;
double a21 = y3 - y2;
double a22 = y0 - y1;
double b1 = x0 - x2;
double b2 = y0 - y2;
double djacob = a11 * a22 - a21 * a12;
if (Math.Abs(djacob) < Zero)
{
return(false);//line parrel, no cross point
}
double t1 = (a22 * b1 - a12 * b2) / djacob;
double t2 = (-a21 * b1 + a11 * b2) / djacob;
//calculate cross point
outx = x2 + (x3 - x2) * t1;
outy = y2 + (y3 - y2) * t1;
if (option == ExtendOption.None)
{
if (t1 > -Zero && t1 < (1 + Zero) && t2 > -Zero && t2 < (1 + Zero))
{
return(true);
}
}
else if (option == ExtendOption.This)
{
if (t1 > -Zero && t1 < (1 + Zero))
{
return(true);
}
}
else if (option == ExtendOption.Other)
{
if (t2 > -Zero && t2 < (1 + Zero))
{
return(true);
}
}
else if (option == ExtendOption.Both)
{
return(true);
}
return(false);
}
// line 1: (x0,y0)-(x1,y1), line 2: (x2,y2)-(x3,y3)
// intersection point: (outx, outy)
// return value: false (no intersection point), true (1 intersection point)
//
public static bool LineIntersectWithLine(
double x0, double y0, double x1, double y1,
double x2, double y2, double x3, double y3,
ref double outx, ref double outy,
ExtendOption option)
{
double a11 = x3 - x2;
double a12 = x0 - x1;
double a21 = y3 - y2;
double a22 = y0 - y1;
double b1 = x0 - x2;
double b2 = y0 - y2;
double djacob = a11 * a22 - a21 * a12;
if (Math.Abs(djacob) < Zero)
return false;//line parrel, no cross point
double t1 = (a22 * b1 - a12 * b2) / djacob;
double t2 = (-a21 * b1 + a11 * b2) / djacob;
//calculate cross point
outx = x2 + (x3 - x2) * t1;
outy = y2 + (y3 - y2) * t1;
if (option == ExtendOption.None)
{
if (t1 > -Zero && t1 < (1 + Zero) && t2 > -Zero && t2 < (1 + Zero))
return true;
}
else if (option == ExtendOption.This)
{
if (t1 > -Zero && t1 < (1 + Zero))
return true;
}
else if (option == ExtendOption.Other)
{
if (t2 > -Zero && t2 < (1 + Zero))
return true;
}
else if (option == ExtendOption.Both)
return true;
return false;
}
