public static bool Intersect(PointLf ap1, PointLf ap2, PointLf bp1, PointLf bp2, ref PointLf ip)
{
const double intersectionEpsilon = 1.0e-30;
double under = (bp2.Y - bp1.Y) * (ap2.X - ap1.X) - (bp2.X - bp1.X) * (ap2.Y - ap1.Y);
if (under < intersectionEpsilon)
{
return(false);
}
double _t = (bp2.X - bp1.X) * (ap1.Y - bp1.Y) - (bp2.Y - bp1.Y) * (ap1.X - bp1.X);
double _s = (ap2.X - ap1.X) * (ap1.Y - bp1.Y) - (ap2.Y - ap1.Y) * (ap1.X - bp1.X);
double t = _t / under;
double s = _s / under;
if (t < 0.0 || t > 1.0 || s < 0.0 || s > 1.0)
{
return(false);
}
if (_t == 0 && _s == 0)
{
return(false);
}
ip.X = ap1.X + t * (double)(ap2.X - ap1.X);
ip.Y = ap1.Y + t * (double)(ap2.Y - ap1.Y);
return(true);
}
public static PointLf CalRotatedPointLf(PointLf ptStartPointLf, double fRotationDegree, bool cw)
{
var ptRotationCenter = new PointLf(0, 0);
if (cw)
{
return(CalCWRotatedPointLf(ptStartPointLf, fRotationDegree, ptRotationCenter));
}
else
{
return(CalCCWRotatedPointLf(ptStartPointLf, fRotationDegree, ptRotationCenter));
}
}
public static PointLf CalCCWRotatedPointLf(PointLf ptStartPointLf, double fRotationDegree, PointLf ptRotationCenter)
{
PointLf ptDestPointLf = new PointLf(0, 0); //시작점과 회전각도로 계산할 끝점
const double TWOPI = Math.PI * 2;
//끝점 계산
//원점을 기준으로 {x, y}를 시계방향으로 a(radian)만큼 회전시킨 점을 구하는 공식.
//x' = x*Math.Cos(a) + y*Math.Sin(a)
//y' = -x*Math.Sin(a) + y*Math.Cos(a)
double fTotalRotationRadian = fRotationDegree * TWOPI / 360;
ptDestPointLf.X = (ptStartPointLf.X - ptRotationCenter.X) * Math.Cos(fTotalRotationRadian)
+ (ptStartPointLf.Y - ptRotationCenter.Y) * Math.Sin(fTotalRotationRadian) + ptRotationCenter.X;
ptDestPointLf.Y = -(ptStartPointLf.X - ptRotationCenter.X) * Math.Sin(fTotalRotationRadian)
+ (ptStartPointLf.Y - ptRotationCenter.Y) * Math.Cos(fTotalRotationRadian) + ptRotationCenter.Y;
return(ptDestPointLf);
}
public static bool Intersect(PointLf ap, PointLf bp, ref PointLf ip)
{
var zero = new PointLf(0, 0);
return(Intersect(zero, ap, zero, bp, ref ip));
}
public static PointLf CalCCWRotatedPointLf(PointLf ptStartPointLf, double fRotationDegree)
{
var ptRotationCenter = new PointLf(0, 0);
return(CalCCWRotatedPointLf(ptStartPointLf, fRotationDegree, ptRotationCenter));
}
