/// <summary>
/// Determines which side of a line a horizontal line segment lies on.
/// Used in point in polygon.
/// </summary>
/// <param name="hr">The horizontal line segment</param>
/// <returns>Code indicating the position of the horizontal segment with respect to this line.
/// Side.Left if the horizontal segment is to the left of this line; Side.Right if to the
/// right of this line; Side.Unknown if the side cannot be determined (this line is
/// horizontal).
/// </returns>
internal override Side GetSide(HorizontalRay hr)
{
// Express the end of the horizontal in a local system with
// the same origin as the circle this arc lies on.
IPosition center = m_Circle.Center;
QuadVertex pos = new QuadVertex(center, hr.End);
Quadrant quad = pos.Quadrant;
// Assign the side code, assuming the arc is clockwise.
Side result = (quad == Quadrant.NE || quad == Quadrant.SE ? Side.Right : Side.Left);
// If the horizontal is apparently to the right of the curve,
// but the location in question coincides with the extreme
// north point of the circle, reverse the side (it's OK in
// the extreme south).
if (result == Side.Right)
{
double maxnorth = center.Y + Circle.Radius;
if (Math.Abs(maxnorth - hr.Y) < Constants.TINY)
{
result = Side.Left;
}
}
// If the arc actually goes anti-clockwise, reverse the side.
if (!m_IsClockwise)
{
result = (result == Side.Left ? Side.Right : Side.Left);
}
return(result);
}
/// <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>
/// Determines which side of a line a horizontal line segment lies on.
/// Used in point in polygon.
/// </summary>
/// <param name="hr">The horizontal line segment</param>
/// <returns>Code indicating the position of the horizontal segment with respect to this line.
/// Side.Left if the horizontal segment is to the left of this line; Side.Right if to the
/// right of this line; Side.Unknown if the side cannot be determined (this line is
/// horizontal).
/// </returns>
internal override Side GetSide(HorizontalRay hr)
{
// Find the segment containing the end of the horizontal segment
IPointGeometry[] data = Data;
int seg = FindSegment(data, true, 0, hr.End);
if (seg < 0)
{
return(Side.Unknown); // not found => big problem!
}
// What's the northing of the horizontal segment guy?
double hy = hr.Y;
// Scan the remainder of the line, looking for a point which is
// off the horizontal. If below the horizontal, it's to the right
// of the line (& above=>left).
for (int i = seg + 1; i < data.Length; i++)
{
double y = data[i].Y;
if ((hy - y) > Constants.TINY) // y<hy
{
return(Side.Right);
}
if ((y - hy) > Constants.TINY) // y>hy
{
return(Side.Left);
}
}
// If we didn't find any suitable points, try traversing back down
// the line, and adopt the reverse logic for figuring out the side.
for (int i = seg; i >= 0; i--)
{
double y = data[i].Y;
if ((y - hy) > Constants.TINY) // y>hy
{
return(Side.Right);
}
if ((hy - y) > Constants.TINY) // y<hy
{
return(Side.Left);
}
}
// The line is completely horizontal, so we have an intersection
// at the start or the end of the line. This should have already
// been caught, so we're f****d now.
return(Side.Unknown);
}
/// <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));
}
/// <summary>
/// Determines which side of a line a horizontal line segment lies on.
/// Used in point in polygon.
/// </summary>
/// <param name="hr">The horizontal line segment</param>
/// <returns>Code indicating the position of the horizontal segment with respect to this line.
/// Side.Left if the horizontal segment is to the left of this line; Side.Right if to the
/// right of this line; Side.Unknown if the side cannot be determined (this line is
/// horizontal).
/// </returns>
internal override Side GetSide(HorizontalRay hr)
{
// The end of the horizontal segment should be coincident with this segment.
IPosition e = hr.End;
if (this.Distance(e).Meters > Constants.XYTOL)
{
return(Side.Unknown);
}
// What's the northing of the horizontal segment guy?
double hy = hr.Y;
// Scan the remainder of the line, looking for a point which is
// off the horizontal. If below the horizontal, it's to the right
// of the line (& above=>left).
double y = End.Y;
if ((hy - y) > Constants.TINY) // y<hy
{
return(Side.Right);
}
if ((y - hy) > Constants.TINY) // y>hy
{
return(Side.Left);
}
// If we didn't find any suitable points, try traversing back down
// the line, and adopt the reverse logic for figuring out the side.
y = Start.Y;
if ((y - hy) > Constants.TINY) // y>hy
{
return(Side.Right);
}
if ((hy - y) > Constants.TINY) // y<hy
{
return(Side.Left);
}
// The line is completely horizontal, so we have an intersection
// at the start or the end of the line. This should have already
// been caught, so we're f****d now.
return(Side.Unknown);
}
/// <summary>
/// Creates new <c>Orientation</c> based on the supplied horizontal ray.
/// </summary>
/// <param name="hr"></param>
internal Orientation(HorizontalRay hr)
{
// Remember the stuff we were supplied (since we are not starting
// with a divider, it has to be null).
m_Divider = null;
m_IsStart = false;
// The horizontal segment is ALWAYS at the very start of the
// north-west quadrant.
m_Quadrant = Quadrant.NW;
// Convert the deltas into the IJ coordinate system for the
// north-west quadrant (the angle defined with I/J should
// evaluate to zero, since the horizontal segment is at the
// start of the quadrant).
m_DeltaI = 0.0;
m_DeltaJ = hr.EndX - hr.StartX;
}
/// <summary>
/// Determines which side of a divider a horizontal line segment lies on.
/// Used in point in polygon.
/// </summary>
/// <param name="id">The divider to process</param>
/// <param name="s">Start of horizontal segment.</param>
/// <param name="e">End of segment.</param>
/// <param name="od">The divider the side refers to. This usually refers to
/// the supplied divider, but may refer to another divider in a situation where the
/// horizontal segment passes directly through one end of <paramref name="d"/>.</param>
/// <returns>Side.Left if the line is to the left of the divider, Side.Right
/// if line to the right, Side.On if the end of the line is coincident with
/// the divider, Side.Unknown if an error arose.</returns>
/// <remarks>
/// Rather than passing in 2 PointGeometry objects, it would be better to pass
/// in a HorizontalRay object, since 2 arbitrary positions are not guaranteed
/// to be horizontal.
/// </remarks>
internal static Side GetSide(IDivider id, IPointGeometry s, IPointGeometry e, out IDivider od)
{
// If the end of the horizontal segment hits the start or
// the end of the specified divider, we have a situation where the divider
// may not be the divider which is adjacent to the segment. In
// that case, use special code to determine the side code.
// Otherwise just convert the supplied divider into a line, and get the
// side code by looking for a vertex which has a different
// northing from that of the horizontal segment.
Debug.Assert(s.Easting.Microns <= e.Easting.Microns);
double d = e.Easting.Meters - s.Easting.Meters;
Debug.Assert(d>=0.0);
HorizontalRay hseg = new HorizontalRay(s, d);
if (e.IsCoincident(id.From) || e.IsCoincident(id.To)) // e both times!
return hseg.GetSide(id, e.IsCoincident(id.From), out od);
else
{
od = id;
return od.LineGeometry.GetSide(hseg);
}
}
/// <summary>
/// Creates new <c>Orientation</c> based on the supplied horizontal ray.
/// </summary>
/// <param name="hr"></param>
internal Orientation(HorizontalRay hr)
{
// Remember the stuff we were supplied (since we are not starting
// with a divider, it has to be null).
m_Divider = null;
m_IsStart = false;
// The horizontal segment is ALWAYS at the very start of the
// north-west quadrant.
m_Quadrant = Quadrant.NW;
// Convert the deltas into the IJ coordinate system for the
// north-west quadrant (the angle defined with I/J should
// evaluate to zero, since the horizontal segment is at the
// start of the quadrant).
m_DeltaI = 0.0;
m_DeltaJ = hr.EndX - hr.StartX;
}
/// <summary>
/// Determines which side of a line a horizontal line segment lies on.
/// Used in point in polygon.
/// </summary>
/// <param name="hr">The horizontal line segment</param>
/// <returns>Code indicating the position of the horizontal segment with respect to this line.
/// Side.Left if the horizontal segment is to the left of this line; Side.Right if to the
/// right of this line; Side.Unknown if the side cannot be determined (this line is
/// horizontal).
/// </returns>
internal override Side GetSide(HorizontalRay hr)
{
// The end of the horizontal segment should be coincident with this segment.
IPosition e = hr.End;
if (this.Distance(e).Meters > Constants.XYTOL)
return Side.Unknown;
// What's the northing of the horizontal segment guy?
double hy = hr.Y;
// Scan the remainder of the line, looking for a point which is
// off the horizontal. If below the horizontal, it's to the right
// of the line (& above=>left).
double y = End.Y;
if ((hy-y) > Constants.TINY) // y<hy
return Side.Right;
if ((y-hy) > Constants.TINY) // y>hy
return Side.Left;
// If we didn't find any suitable points, try traversing back down
// the line, and adopt the reverse logic for figuring out the side.
y = Start.Y;
if ((y-hy) > Constants.TINY) // y>hy
return Side.Right;
if ((hy-y) > Constants.TINY) // y<hy
return Side.Left;
// The line is completely horizontal, so we have an intersection
// at the start or the end of the line. This should have already
// been caught, so we're f****d now.
return Side.Unknown;
}
/// <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));
}
/// <summary>
/// Determines which side of a line a horizontal line segment lies on.
/// Used in point in polygon.
/// </summary>
/// <param name="hr">The horizontal line segment</param>
/// <returns>Code indicating the position of the horizontal segment with respect to this line.
/// Side.Left if the horizontal segment is to the left of this line; Side.Right if to the
/// right of this line; Side.Unknown if the side cannot be determined (this line is
/// horizontal).
/// </returns>
internal override Side GetSide(HorizontalRay hr)
{
// Express the end of the horizontal in a local system with
// the same origin as the circle this arc lies on.
IPosition center = m_Circle.Center;
QuadVertex pos = new QuadVertex(center, hr.End);
Quadrant quad = pos.Quadrant;
// Assign the side code, assuming the arc is clockwise.
Side result = (quad==Quadrant.NE || quad==Quadrant.SE ? Side.Right : Side.Left);
// If the horizontal is apparently to the right of the curve,
// but the location in question coincides with the extreme
// north point of the circle, reverse the side (it's OK in
// the extreme south).
if (result==Side.Right)
{
double maxnorth = center.Y + Circle.Radius;
if (Math.Abs(maxnorth - hr.Y) < Constants.TINY)
result = Side.Left;
}
// If the arc actually goes anti-clockwise, reverse the side.
if (!m_IsClockwise)
result = (result==Side.Left ? Side.Right : Side.Left);
return result;
}
/// <summary>
/// Determines which side of a line a horizontal line segment lies on.
/// Used in point in polygon.
/// </summary>
/// <param name="hr">The horizontal line segment</param>
/// <returns>Code indicating the position of the horizontal segment with respect to this line.
/// Side.Left if the horizontal segment is to the left of this line; Side.Right if to the
/// right of this line; Side.Unknown if the side cannot be determined (this line is
/// horizontal).
/// </returns>
internal override Side GetSide(HorizontalRay hr)
{
return Make().GetSide(hr);
}
/// <summary>
/// Determines which side of a line a horizontal line segment lies on.
/// Used in point in polygon.
/// </summary>
/// <param name="hr">The horizontal line segment</param>
/// <returns>Code indicating the position of the horizontal segment with respect to this line.
/// Side.Left if the horizontal segment is to the left of this line; Side.Right if to the
/// right of this line; Side.Unknown if the side cannot be determined (this line is
/// horizontal).
/// </returns>
internal override Side GetSide(HorizontalRay hr)
{
return(Make().GetSide(hr));
}
/// <summary> /// Determines which side of a line a horizontal line segment lies on. /// Used in point in polygon. /// </summary> /// <param name="hr">The horizontal line segment</param> /// <returns>Code indicating the position of the horizontal segment with respect to this line. /// Side.Left if the horizontal segment is to the left of this line; Side.Right if to the /// right of this line; Side.Unknown if the side cannot be determined (this line is /// horizontal). /// </returns> internal abstract Side GetSide(HorizontalRay hr);
/// <summary>
/// Determines which side of a line a horizontal line segment lies on.
/// Used in point in polygon.
/// </summary>
/// <param name="hr">The horizontal line segment</param>
/// <returns>Code indicating the position of the horizontal segment with respect to this line.
/// Side.Left if the horizontal segment is to the left of this line; Side.Right if to the
/// right of this line; Side.Unknown if the side cannot be determined (this line is
/// horizontal).
/// </returns>
internal override Side GetSide(HorizontalRay hr)
{
// Find the segment containing the end of the horizontal segment
IPointGeometry[] data = Data;
int seg = FindSegment(data, true, 0, hr.End);
if (seg<0)
return Side.Unknown; // not found => big problem!
// What's the northing of the horizontal segment guy?
double hy = hr.Y;
// Scan the remainder of the line, looking for a point which is
// off the horizontal. If below the horizontal, it's to the right
// of the line (& above=>left).
for (int i=seg+1; i<data.Length; i++)
{
double y = data[i].Y;
if ((hy-y) > Constants.TINY) // y<hy
return Side.Right;
if ((y-hy) > Constants.TINY) // y>hy
return Side.Left;
}
// If we didn't find any suitable points, try traversing back down
// the line, and adopt the reverse logic for figuring out the side.
for (int i=seg; i>=0; i--)
{
double y = data[i].Y;
if ((y-hy) > Constants.TINY) // y>hy
return Side.Right;
if ((hy-y) > Constants.TINY) // y<hy
return Side.Left;
}
// The line is completely horizontal, so we have an intersection
// at the start or the end of the line. This should have already
// been caught, so we're f****d now.
return Side.Unknown;
}
/// <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;
// Get the window of the circle that this curve lies on.
IWindow cwin = m_Circle.Extent;
// Get a window for the horizontal segment.
IWindow segwin = new Window(s, e);
// Return if the windows don't overlap.
if (!cwin.IsOverlap(segwin))
{
return(false);
}
// Return if the the segment is to the west of the circle's window.
if (segwin.Max.X < cwin.Min.X)
{
return(false);
}
// 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);
}
// Locate up to two intersections of the horizontal segment with the circle.
IPosition x1 = null;
IPosition x2 = null;
uint nx = hseg.Intersect(m_Circle, ref x1, ref x2);
// Return if no intersections
if (nx == 0)
{
return(false);
}
// Return if this arc curve is a complete circle.
if (this.IsCircle)
{
return(false);
}
// Check whether the first intersection lies on this arc. If
// so, update the end of segment, and return.
if (CircularArcGeometry.IsInSector(this, x1, 0.0))
{
e = new PointGeometry(x1);
return(true);
}
// If we got two intersections with the circle, check the
// second intersection as well.
if (nx == 2 && CircularArcGeometry.IsInSector(this, x2, 0.0))
{
e = new PointGeometry(x2);
return(true);
}
return(false);
}
/// <summary> /// Determines which side of a line a horizontal line segment lies on. /// Used in point in polygon. /// </summary> /// <param name="hr">The horizontal line segment</param> /// <returns>Code indicating the position of the horizontal segment with respect to this line. /// Side.Left if the horizontal segment is to the left of this line; Side.Right if to the /// right of this line; Side.Unknown if the side cannot be determined (this line is /// horizontal). /// </returns> abstract internal Side GetSide(HorizontalRay hr);
/// <summary>
/// Creates a new <c>ConnectionFinder</c> at a specific end of a divider.
/// Defines the next divider in the nodal cycle (reckoned anticlockwise),
/// along with a flag to indicate whether it is the start or end of the divider.
/// <para/>
/// If the parameters supplied refer to a dangling divider, the result will
/// be the SAME as the supplied info.
/// <para/>
/// This constructor is normally used during polygon formation. It is also used
/// to resolve a special case in point in polygon tests, where the directed
/// line (a <c>HorizontalRay</c> object) intersects at a node. In that case,
/// the supplied divider refers to any one of the dividers incident on the
/// node, and the connection to be formed is actually the connection for
/// the <c>HorizontalRay</c> object.
/// </summary>
/// <param name="from">The divider entering the node.</param>
/// <param name="isFromStart">True if it's the start of the divider.</param>
/// <param name="ray">Optional reference line (used when doing special point
/// in polygon tests).</param>
internal ConnectionFinder(IDivider from, bool isFromStart, HorizontalRay ray)
{
Debug.Assert(from != null);
// Initialize with default values
m_Next = null;
m_IsStart = false;
// Get the location involved
ITerminal loc = (isFromStart ? from.From : from.To);
// Get the dividers incident on the terminal.
IDivider[] da = loc.IncidentDividers();
// Get orientation info for each divider (the list could conceivably
// grow if dividers start at the terminal, then loop round to also
// finish at the same terminal).
List <Orientation> orient = new List <Orientation>(da.Length);
// If we are doing special stuff for point in polygon, add an extra orientation
// object to refer to the HorizontalRay object.
if (ray != null)
{
Orientation o = new Orientation(ray);
orient.Add(o);
}
foreach (IDivider d in da)
{
// 03-APR-2003: Try ignoring boundaries that have zero-length
//if (!b.HasLength)
// continue;
// Check if the start of the divider is incident on the node.
// If so, append the orientation info to the list.
if (d.From.IsCoincident(loc))
{
orient.Add(new Orientation(d, true));
}
// Likewise for the end of the divider (it could start AND end at the node).
if (d.To.IsCoincident(loc))
{
orient.Add(new Orientation(d, false));
}
}
// We MUST have at least one orientation point (two if a horizontal ray is also included)
Debug.Assert(orient.Count > (ray == null ? 0 : 1));
// If we have only one orientation point, we have a dangle,
// so return the information we were supplied.
if (ray == null && orient.Count == 1)
{
m_Next = from;
m_IsStart = isFromStart;
return;
}
// Get a reference to the orientation info for the source divider (if
// we are doing point in polygon stuff, we stashed the reference
// segment in the first slot).
Orientation source = null;
if (ray != null)
{
source = orient[0];
}
else
{
source = orient.Find(o => (o.Divider == from && o.IsStart == isFromStart));
Debug.Assert(source != null);
}
// If we have only two orientation points, the one we want
// if the one which does not match the source.
if (orient.Count == 2)
{
Orientation o = (source == orient[0] ? orient[1] : orient[0]);
m_Next = o.Divider;
m_IsStart = o.IsStart;
return;
}
// Handle any curves.
if (HasAnyCurves(orient))
{
source.SetCurves(orient);
}
// If there are any other boundaries in the source quadrant,
// try to find an anticlockwise divider (with the highest
// orientation angle which is less than that of the source).
Orientation next = FindPrevMax(source, orient);
// If we got something, we're all done.
if (next != null)
{
m_Next = next.Divider;
m_IsStart = next.IsStart;
return;
}
// Loop through the quadrants, looking for the next divider. We
// scan the quadrants anticlockwise, including the source
// quadrant we may have just processing (possibility that the
// next divider is further on in the source quadrant).
Quadrant search = NextQuadrant(source.Quadrant);
for (int i = 0; i < 4; i++, search = NextQuadrant(search))
{
next = FindMax(search, source, orient);
if (next != null)
{
m_Next = next.Divider;
m_IsStart = next.IsStart;
return;
}
}
throw new Exception("ConnectionFinder: network error");
}
/// <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;
// Get the window of the circle that this curve lies on.
IWindow cwin = m_Circle.Extent;
// Get a window for the horizontal segment.
IWindow segwin = new Window(s, e);
// Return if the windows don't overlap.
if (!cwin.IsOverlap(segwin))
return false;
// Return if the the segment is to the west of the circle's window.
if (segwin.Max.X < cwin.Min.X)
return false;
// 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;
}
// Locate up to two intersections of the horizontal segment with the circle.
IPosition x1=null;
IPosition x2=null;
uint nx = hseg.Intersect(m_Circle, ref x1, ref x2);
// Return if no intersections
if (nx==0)
return false;
// Return if this arc curve is a complete circle.
if (this.IsCircle)
return false;
// Check whether the first intersection lies on this arc. If
// so, update the end of segment, and return.
if (CircularArcGeometry.IsInSector(this, x1, 0.0))
{
e = new PointGeometry(x1);
return true;
}
// If we got two intersections with the circle, check the
// second intersection as well.
if (nx==2 && CircularArcGeometry.IsInSector(this, x2, 0.0))
{
e = new PointGeometry(x2);
return true;
}
return false;
}