/// <summary>
/// Cuts back a horizontal line segment to the closest intersection with this line.
/// Used in point in polygon.
/// </summary>
/// <param name="s">Start of horizontal segment.</param>
/// <param name="e">End of segment (will be modified if segment intersects this line)</param>
/// <param name="status">Return code indicating whether an error has arisen (returned
/// as 0 if no error).</param>
/// <returns>True if the horizontal line was cut back.</returns>
internal override bool GetCloser(IPointGeometry s, ref PointGeometry e, out uint status)
{
status = 0;
// Remember the initial end of segment
PointGeometry initEnd = new PointGeometry(e);
// Represent the horizontal segment in a class of its own
HorizontalRay hseg = new HorizontalRay(s, e.X - s.X);
if (!hseg.IsValid)
{
status = 1;
return(false);
}
IPointGeometry[] data = this.Data;
// Get relative position code for the start of the line. If it's
// somewhere on the horizontal segment, cut the line back.
byte scode = Geom.GetPositionCode(data[0], s, e);
if (scode == 0)
{
e = new PointGeometry(Start);
}
// Loop through each line segment, testing the end of each segment
// against the horizontal segment.
byte ecode;
for (int i = 1; i < data.Length; scode = ecode, i++)
{
// Get the position code for the end of the line segment
ecode = Geom.GetPositionCode(data[i], s, e);
// If it's coincident with the horizontal segment, cut the
// line back. Otherwise see whether there is any potential
// intersection to cut back to.
if (ecode == 0)
{
e = new PointGeometry(data[i]);
}
else if ((scode & ecode) == 0)
{
IPosition x = null;
if (hseg.Intersect(data[i - 1], data[i], ref x))
{
e = new PointGeometry(x);
}
}
}
// Return flag to indicate whether we got closer or not.
return(!e.IsCoincident(initEnd));
}
/// <summary>
/// Cuts back a horizontal line segment to the closest intersection with this line.
/// Used in point in polygon.
/// </summary>
/// <param name="s">Start of horizontal segment.</param>
/// <param name="e">End of segment (will be modified if segment intersects this line)</param>
/// <param name="status">Return code indicating whether an error has arisen (returned
/// as 0 if no error).</param>
/// <returns>True if the horizontal line was cut back.</returns>
internal override bool GetCloser(IPointGeometry s, ref PointGeometry e, out uint status)
{
status = 0;
// Remember the initial end of segment
PointGeometry initEnd = new PointGeometry(e);
// Represent the horizontal segment in a class of its own
HorizontalRay hseg = new HorizontalRay(s, e.X - s.X);
if (!hseg.IsValid)
{
status = 1;
return(false);
}
// Get relative position code for the start of the line. If it's
// somewhere on the horizontal segment, cut the line back.
byte scode = Geom.GetPositionCode(Start, s, e);
if (scode == 0)
{
e = new PointGeometry(Start);
}
// Get the position code for the end of the line segment
byte ecode = Geom.GetPositionCode(End, s, e);
// If it's coincident with the horizontal segment, cut the
// line back. Otherwise see whether there is any potential
// intersection to cut back to.
if (ecode == 0)
{
e = new PointGeometry(End);
}
else if ((scode & ecode) == 0)
{
IPosition x = null;
if (hseg.Intersect(Start, End, ref x))
{
e = new PointGeometry(x);
}
}
// Return flag to indicate whether we got closer or not.
return(!e.IsCoincident(initEnd));
}
