private static PointClassification ClassifyX(this PointX p, SegmentX s)
{
var a = s.End - s.Start;
var b = p - s.Start;
double sa = a.X * b.Y - b.X * a.Y;
if (sa > 0.0)
{
return(PointClassification.LEFT);
}
if (sa < 0.0)
{
return(PointClassification.RIGHT);
}
if ((a.X * b.X < 0.0) || (a.Y * b.Y < 0.0))
{
return(PointClassification.BEHIND);
}
if (a.Length2 < b.Length2)
{
return(PointClassification.BEYOND);
}
if (s.Start.Equals(p))
{
return(PointClassification.ORIGIN);
}
if (s.End.Equals(p))
{
return(PointClassification.DESTINATION);
}
return(PointClassification.BETWEEN);
}
private static PointToPolygonPositionType GetPositionToPolygon(this PointX p, PolygonX polygon)
{
var parity = true;
for (var i = 0; i < polygon.Vertices.Length; i++)
{
var v1 = polygon.Vertices[i];
var v2 = polygon.Vertices[(i + 1) % polygon.Vertices.Length];
var segment = new SegmentX(v1, v2);
switch (ClassifyEdgeX(p, segment))
{
case EdgeType.TOUCHING:
return(PointToPolygonPositionType.Boundary);
case EdgeType.CROSSING:
parity = !parity;
break;
}
}
return(parity ? PointToPolygonPositionType.Outside : PointToPolygonPositionType.Inside);
}
private static EdgeType ClassifyEdgeX(PointX a, SegmentX e)
{
var v = e.Start;
var w = e.End;
switch (a.ClassifyX(e))
{
case PointClassification.LEFT:
return(((v.Y < a.Y) && (a.Y <= w.Y)) ? EdgeType.CROSSING : EdgeType.INESSENTIAL);
case PointClassification.RIGHT:
return(((w.Y < a.Y) && (a.Y <= v.Y)) ? EdgeType.CROSSING : EdgeType.INESSENTIAL);
case PointClassification.BETWEEN:
case PointClassification.ORIGIN:
case PointClassification.DESTINATION:
return(EdgeType.TOUCHING);
default:
return(EdgeType.INESSENTIAL);
}
}
