////////////////////////////////////////////////////////////////////////////////////////////////////
/// <summary>
/// Determine if a point is to the left of this edge when facing from the start vertex to the end
/// vertex.
/// </summary>
/// <remarks> Darrellp, 2/18/2011. </remarks>
/// <param name="pt"> Point to check out. </param>
/// <returns> true if it succeeds, false if it fails. </returns>
////////////////////////////////////////////////////////////////////////////////////////////////////
public bool FLeftOf(Vector pt)
{
// We should never have a start vertex at infinity
//
// Fortune.ProcessRay(), which creates the vertices at infinity, specifically makes sure that
// this never happens (except with edges at infinity which are really placeholders for the
// winged edge structure and have no position at all. They aren't processed here (and if they
// were, it would be a problem). While this is a touch Fortune specific, there's no reason not to
// insist on it in the general case.
// If the end vtx is at infinity, convert it to a real point
var pt1 = VtxStart.Pt;
var pt2 = VtxEnd.FAtInfinity ? VtxEnd.ConvertToReal(pt1, 10) : VtxEnd.Pt;
// Do the geometry on pt1 and pt2
return(Geometry2D.FLeft(pt1, pt2, pt));
}
// In the tree, left is "above", right is "below"
internal override bool ShouldTravelLeft(T x, T y)
{
// We want to go left if we're above - i.e., to the left of the line travelling
// from left to right.
return(Geometry2D.FLeft(_leftEnd, _rightEnd, new Vector(x, y)));
}