public V2d GetClosestPointOnLine(V2d p)
{
var d = P0 - P1;
var l = d.LengthSquared;
if (Fun.IsTiny(l))
{
return(P0); //it does not matter which of the two points we choose
}
var t = (P0.Dot(d) - p.Dot(d)) / l; //parametric distance from P0 to P1, where closest point to p is
if (t <= 0)
{
return(P0);
}
if (t >= 1)
{
return(P1);
}
return(P0 - t * d);
}