//点Pから線分ABへの最も近い点を探索する
public static TwoDimensionalVector nearest(TwoDimensionalVector A, TwoDimensionalVector B, TwoDimensionalVector P)
{
TwoDimensionalVector a = new TwoDimensionalVector(B.x - A.x, B.y - A.y);
TwoDimensionalVector b = new TwoDimensionalVector(P.x - A.x, P.y - A.y);
double r = (a.x * b.x + a.y * b.y) / (a.x * a.x + a.y * a.y);
if (r <= 0)
{
return(A);
}
else if (r >= 1)
{
return(B);
}
else
{
TwoDimensionalVector result = new TwoDimensionalVector(A.x + r * a.x, A.y + r * a.y);
return(result);
}
}
//線分ABの長さ
public static double distance(TwoDimensionalVector A, TwoDimensionalVector B)
{
return(Math.Sqrt((A.x - B.x) * (A.x - B.x) + (A.y - B.y) * (A.y - B.y)));
}
