/// <summary>
///
/// </summary>
/// <param name="u"></param>
/// <param name="v"></param>
/// <param name="w"></param>
/// <param name="tu"></param>
/// <param name="tv"></param>
private static bool LineLineIntersection(Vec2d u, Vec2d v, Vec2d w, out double tu, out double tv)
{
// impl ref
// https://www.codeproject.com/Tips/862988/Find-the-Intersection-Point-of-Two-Line-Segments
var c = Vec2d.Cross(u, v);
if (Math.Abs(c) > 0.0)
{
c = 1.0 / c;
tu = Vec2d.Cross(w, v) * c;
tv = Vec2d.Cross(w, u) * c;
return(true);
}
// lines are parallel, no solution
tu = tv = 0.0;
return(false);
}
/// <summary>
///
/// </summary>
/// <param name="points"></param>
/// <returns></returns>
public static double GetPolygonArea(IEnumerable <Vec2d> points)
{
var itr = points.GetEnumerator();
itr.MoveNext();
var first = itr.Current;
var p0 = first;
var sum = 0.0;
while (itr.MoveNext())
{
var p1 = itr.Current;
sum += Vec2d.Cross(p0, p1);
p0 = p1;
}
sum += Vec2d.Cross(p0, first);
return(sum * 0.5);
}
