///<summary>
/// Computes the <see cref="Coordinate"/> for the point on the line at the given index, offset by the given distance.
///</summary>
/// <remarks>
/// If the index is out of range the first or last point on the line will be returned.
/// The computed point is offset to the left of the line if the offset distance is
/// positive, to the right if negative.
/// The Z-ordinate of the computed point will be interpolated from the Z-ordinates of the line segment containing it, if they exist.
/// </remarks>
/// <param name="index">The index of the desired point</param>
/// <param name="offsetDistance">The distance the point is offset from the segment (positive is to the left, negative is to the right)</param>
/// <returns>The Coordinate at the given index</returns>
public Coordinate ExtractPoint(double index, double offsetDistance)
{
LinearLocation loc = LengthLocationMap.GetLocation(_linearGeom, index);
LinearLocation locLow = loc.ToLowest(_linearGeom);
return(locLow.GetSegment(_linearGeom).PointAlongOffset(locLow.SegmentFraction, offsetDistance));
}
/// <summary>
/// Computes the indices for a subline of the line.
/// (The subline must conform to the line; that is,
/// all vertices in the subline (except possibly the first and last)
/// must be vertices of the line and occur in the same order).
/// </summary>
/// <param name="subLine">A subLine of the line.</param>
/// <returns>A pair of indices for the start and end of the subline..</returns>
public double[] IndicesOf(IGeometry subLine)
{
LinearLocation[] locIndex = LocationIndexOfLine.IndicesOf(_linearGeom, subLine);
double[] index =
{
LengthLocationMap.GetLength(_linearGeom, locIndex[0]),
LengthLocationMap.GetLength(_linearGeom, locIndex[1])
};
return(index);
}
/// <summary>
/// Computes the length for a given <see cref="LinearLocation" />
/// on a linear <see cref="Geometry" />.
/// </summary>
/// <param name="linearGeom">The linear geometry to use.</param>
/// <param name="loc">The <see cref="LinearLocation" /> index of the location.</param>
/// <returns>The length for the <see cref="LinearLocation" />.</returns>
public static double GetLength(IGeometry linearGeom, LinearLocation loc)
{
var locater = new LengthLocationMap(linearGeom);
return(locater.GetLength(loc));
}
/// <summary>
/// Computes the <see cref="LinearLocation"/> for a
/// given length along a linear <see cref="IGeometry"/>,
/// with control over how the location
/// is resolved at component endpoints.
/// </summary>
/// <param name="linearGeom">The linear geometry to use</param>
/// <param name="length">The length index of the location</param>
/// <param name="resolveLower">If true lengths are resolved to the lowest possible index</param>
public static LinearLocation GetLocation(IGeometry linearGeom, double length, bool resolveLower)
{
var locater = new LengthLocationMap(linearGeom);
return(locater.GetLocation(length, resolveLower));
}
// TODO: cache computed cumulative length for each vertex
// TODO: support user-defined measures
// TODO: support measure index for fast mapping to a location
/// <summary>
/// Computes the <see cref="LinearLocation" /> for a
/// given length along a linear <see cref="Geometry" />.
/// </summary>
/// <param name="linearGeom">The linear geometry to use.</param>
/// <param name="length">The length index of the location.</param>
/// <returns>The <see cref="LinearLocation" /> for the length.</returns>
public static LinearLocation GetLocation(IGeometry linearGeom, double length)
{
var locater = new LengthLocationMap(linearGeom);
return(locater.GetLocation(length));
}
/// <summary>
///
/// </summary>
/// <param name="index"></param>
/// <returns></returns>
private LinearLocation LocationOf(double index)
{
return(LengthLocationMap.GetLocation(_linearGeom, index));
}
/// <summary>
/// Computes the <see cref="Coordinate" /> for the point
/// on the line at the given index.
/// If the index is out of range the first or last point on the
/// line will be returned.
/// </summary>
/// <remarks>
/// The Z-ordinate of the computed point will be interpolated from
/// the Z-ordinates of the line segment containing it, if they exist.
/// </remarks>
/// <param name="index">The index of the desired point.</param>
/// <returns>The <see cref="Coordinate" /> at the given index.</returns>
public Coordinate ExtractPoint(double index)
{
LinearLocation loc = LengthLocationMap.GetLocation(_linearGeom, index);
return(loc.GetCoordinate(_linearGeom));
}
private LinearLocation LocationOf(double index, bool resolveLower)
{
return(LengthLocationMap.GetLocation(_linearGeom, index, resolveLower));
}