public static intersection line_point_intersect(Vec p1, Vec p2, Vec p0, double rad)
{
var v = new Vec(p2.Y - p1.Y, -(p2.X - p1.X)); // perpendicular vector
var d = Math.Abs((p2.X - p1.X) * (p1.Y - p0.Y) - (p1.X - p0.X) * (p2.Y - p1.Y));
d = d / v.length();
if (d > rad)
{
return(null);
}
v.normalize();
v.scale(d);
var up = p0.add(v);
double ua = 0;
if (Math.Abs(p2.X - p1.X) > Math.Abs(p2.Y - p1.Y))
{
ua = (up.X - p1.X) / (p2.X - p1.X);
}
else
{
ua = (up.Y - p1.Y) / (p2.Y - p1.Y);
}
if (ua > 0.0 && ua < 1.0)
{
return(new intersection()
{
ua = ua, up = up
});
}
return(null);
}
