public void DeleteFromEdgeList(HalfEdge halfEdge)
{
halfEdge.Left.Right = halfEdge.Right;
halfEdge.Right.Left = halfEdge.Left;
halfEdge.IsDeleted = true;
}
// Returns true if point is to right of halfedge edge
private static bool RightSideOf(HalfEdge halfEdge, Point point)
{
var above = false;
var edge = halfEdge.EdgeListEdge;
var topsite = edge.Region1;
var rightOfSite = point.X > topsite.Point.X;
if (rightOfSite && halfEdge.EdgeListSide == Voronoi.LeftSide)
{
return(true);
}
if (!rightOfSite && halfEdge.EdgeListSide == Voronoi.RightSide)
{
return(false);
}
if (Voronoi.IsNearlyEqual(edge.A, 1D))
{
var deltaX = point.X - topsite.Point.X;
var deltaY = point.Y - topsite.Point.Y;
var fast = false;
if (!rightOfSite && edge.B < 0D || rightOfSite && edge.B >= 0D)
{
above = deltaY >= edge.B * deltaX;
fast = above;
}
else
{
above = point.X + point.Y * edge.B > edge.C;
if (edge.B < 0D)
{
above = !above;
}
if (!above)
{
fast = true;
}
}
if (!fast)
{
var dxs = topsite.Point.X - edge.Region0.Point.X;
above = edge.B * (deltaX * deltaX - deltaY * deltaY) < dxs * deltaY * (1.0 + 2.0 * deltaX / dxs + edge.B * edge.B);
if (edge.B < 0)
{
above = !above;
}
}
}
else // edge.b == 1.0
{
var yl = edge.C - edge.A * point.X;
var t1 = point.Y - yl;
var t2 = point.X - topsite.Point.X;
var t3 = yl - topsite.Point.Y;
above = t1 * t1 > t2 * t2 + t3 * t3;
}
return(halfEdge.EdgeListSide == Voronoi.LeftSide ? above : !above);
}