/// <inheritdoc cref="ICoordinateSequenceFilter.Filter"/>
public void Filter(CoordinateSequence seq, int index)
{
/*
* This logic also handles skipping Point geometries
*/
if (index < 1)
{
return;
}
var p0 = seq.GetCoordinate(index - 1);
var p1 = seq.GetCoordinate(index);
double delx = (p1.X - p0.X) / _numSubSegs;
double dely = (p1.Y - p0.Y) / _numSubSegs;
for (int i = 0; i < _numSubSegs; i++)
{
double x = p0.X + i * delx;
double y = p0.Y + i * dely;
var pt = new Coordinate(x, y);
var minPtDist = new PointPairDistance();
DistanceToPoint.ComputeDistance(_geom, pt, minPtDist);
_maxPtDist.SetMaximum(minPtDist);
}
}
/// <summary>
/// Computes the distance from a point to a sequence of line segments.
/// </summary>
/// <param name="p">A point</param>
/// <param name="line">A sequence of contiguous line segments defined by their vertices</param>
/// <returns>The minimum distance between the point and the line segments</returns>
public static double PointToSegmentString(Coordinate p, CoordinateSequence line)
{
if (line.Count == 0)
{
throw new ArgumentException(
"Line array must contain at least one vertex");
}
var lastStart = line.GetCoordinate(0);
var currentEnd = lastStart.Copy();
// this handles the case of length = 1
double minDistance = p.Distance(lastStart);
for (int i = 1; i < line.Count; i++)
{
line.GetCoordinate(i, currentEnd);
double dist = PointToSegment(p, lastStart, currentEnd);
if (dist < minDistance)
{
minDistance = dist;
}
lastStart.CoordinateValue = currentEnd;
}
return(minDistance);
}
public void Filter(CoordinateSequence seq, int i)
{
if (i == 0)
{
return;
}
seq.GetCoordinate(i - 1, p0);
seq.GetCoordinate(i, p1);
rcc.CountSegment(p0, p1);
}
public void Filter(CoordinateSequence seq, int i)
{
// compare to vertex
CheckVertexDistance(seq.GetCoordinate(i));
// compare to segment, if this is one
if (i > 0)
{
CheckSegmentDistance(seq.GetCoordinate(i - 1), seq.GetCoordinate(i));
}
}
private static CoordinateSequence InsertTopologyExceptionPoint(Coordinate coord, CoordinateSequence seq, CoordinateSequenceFactory factory)
{
var res = factory.Create(2 * seq.Count, seq.Ordinates);
if (Replace(seq.GetCoordinate(0), coord))
{
res.SetOrdinate(0, Ordinate.X, coord.X);
res.SetOrdinate(0, Ordinate.Y, coord.Y);
res.SetOrdinate(0, Ordinate.Z, coord.Z);
}
else
{
res.SetOrdinate(0, Ordinate.X, seq.GetOrdinate(0, Ordinate.X));
res.SetOrdinate(0, Ordinate.Y, seq.GetOrdinate(0, Ordinate.Y));
res.SetOrdinate(0, Ordinate.Z, seq.GetOrdinate(0, Ordinate.Z));
}
var last = res.GetCoordinate(0);
int off = 0;
for (int i = 1; i < seq.Count; i++)
{
var curr = seq.GetCoordinate(i);
bool add = true;
if (Replace(curr, coord))
{
res.SetOrdinate(i + off, Ordinate.X, coord.X);
res.SetOrdinate(i + off, Ordinate.Y, coord.Y);
res.SetOrdinate(i + off, Ordinate.Z, coord.Z);
add = false;
}
else if (last.Distance(coord) + coord.Distance(curr) <= 1.000000000000000000001 * last.Distance(curr))
{
res.SetOrdinate(i + off, Ordinate.X, coord.X);
res.SetOrdinate(i + off, Ordinate.Y, coord.Y);
res.SetOrdinate(i + off, Ordinate.Z, coord.Z);
off += 1;
}
if (add)
{
res.SetOrdinate(i + off, Ordinate.X, seq.GetOrdinate(i, Ordinate.X));
res.SetOrdinate(i + off, Ordinate.Y, seq.GetOrdinate(i, Ordinate.Y));
res.SetOrdinate(i + off, Ordinate.Z, seq.GetOrdinate(i, Ordinate.Z));
}
last = curr;
}
var tmp = factory.Create(seq.Count + off, seq.Ordinates);
CoordinateSequences.Copy(res, 0, tmp, 0, tmp.Count);
return(tmp);
}
/// <summary>
/// Function to return a coordinate sequence that is ensured to be closed.
/// </summary>
/// <param name="sequence">The base sequence</param>
/// <param name="factory">The factory to use in case we need to create a new sequence</param>
/// <returns>A closed coordinate sequence</returns>
private static CoordinateSequence EnsureClosedSequence(CoordinateSequence sequence,
CoordinateSequenceFactory factory)
{
//This sequence won't serve a valid linear ring
if (sequence.Count < 3)
{
return(null);
}
//The sequence is closed
var start = sequence.GetCoordinate(0);
int lastIndex = sequence.Count - 1;
var end = sequence.GetCoordinate(lastIndex);
if (start.Equals2D(end))
{
return(sequence);
}
// The sequence is not closed
// 1. Test for a little offset, in that case simply correct x- and y- ordinate values
const double eps = 1E-7;
if (start.Distance(end) < eps)
{
sequence.SetX(lastIndex, start.X);
sequence.SetY(lastIndex, start.Y);
return(sequence);
}
// 2. Close the sequence by adding a new point, this is heavier
var newSequence = factory.Create(sequence.Count + 1, sequence.Dimension, sequence.Measures);
int maxDim = sequence.Dimension;
for (int i = 0; i < sequence.Count; i++)
{
for (int dim = 0; dim < maxDim; dim++)
{
newSequence.SetOrdinate(i, dim, sequence.GetOrdinate(i, dim));
}
}
for (int dim = 0; dim < maxDim; dim++)
{
newSequence.SetOrdinate(sequence.Count, dim, sequence.GetOrdinate(0, dim));
}
return(newSequence);
}
/// <summary>
///
/// </summary>
/// <param name="geom"></param>
protected override void Visit(Geometry geom)
{
if (!(geom is Polygon))
{
return;
}
var elementEnv = geom.EnvelopeInternal;
if (!_rectEnv.Intersects(elementEnv))
{
return;
}
// test each corner of rectangle for inclusion
var rectPt = _rectSeq.CreateCoordinate();
for (int i = 0; i < 4; i++)
{
_rectSeq.GetCoordinate(i, rectPt);
if (!elementEnv.Contains(rectPt))
{
continue;
}
// check rect point in poly (rect is known not to touch polygon at this point)
if (SimplePointInAreaLocator.ContainsPointInPolygon(rectPt, (Polygon)geom))
{
ContainsPoint = true;
return;
}
}
}
/// <summary>
/// Computes the signed area for a ring. The signed area is positive if the
/// <list type="Table">
/// <listheader>
/// <term>value</term>
/// <description>meaning</description>
/// </listheader>
/// <item><term>> 0</term>
/// <description>The ring is oriented clockwise (CW)</description></item>
/// <item><term>< 0</term>
/// <description>The ring is oriented counter clockwise (CCW)</description></item>
/// <item><term>== 0</term>
/// <description>The ring is degenerate or flat</description></item>
/// </list>
/// ring is oriented CW, negative if the ring is oriented CCW, and zero if the
/// ring is degenerate or flat.
/// </summary>
/// <param name="ring">The coordinates forming the ring</param>
/// <returns>The signed area of the ring</returns>
public static double OfRingSigned(CoordinateSequence ring)
{
int n = ring.Count;
if (n < 3)
{
return(0.0);
}
/**
* Based on the Shoelace formula.
* http://en.wikipedia.org/wiki/Shoelace_formula
*/
var p1 = ring.GetCoordinateCopy(0);
var p2 = ring.GetCoordinateCopy(1);
double x0 = p1.X;
p2.X -= x0;
double sum = 0.0;
for (int i = 1; i < n - 1; i++)
{
double p0Y = p1.Y;
p1.X = p2.X;
p1.Y = p2.Y;
ring.GetCoordinate(i + 1, p2);
p2.X -= x0;
sum += p1.X * (p0Y - p2.Y);
}
return(sum / 2.0);
}
/// <summary>
/// Converts sequence
/// </summary>
/// <param name="cs"></param>
/// <returns></returns>
public static IEnumerable <PPoint> ToPPoints(this CoordinateSequence cs)
{
for (int i = 0; i < cs.Count; i++)
{
yield return(cs.GetCoordinate(i).ToPPoint());
}
}
/// <summary>
/// Computes the length of a <c>LineString</c> specified by a sequence of points.
/// </summary>
/// <param name="pts">The points specifying the <c>LineString</c></param>
/// <returns>The length of the <c>LineString</c></returns>
public static double OfLine(CoordinateSequence pts)
{
// optimized for processing CoordinateSequences
int n = pts.Count;
if (n <= 1)
{
return(0.0);
}
double len = 0.0;
var p = pts.GetCoordinateCopy(0);
double x0 = p.X;
double y0 = p.Y;
for (int i = 1; i < n; i++)
{
pts.GetCoordinate(i, p);
double x1 = p.X;
double y1 = p.Y;
double dx = x1 - x0;
double dy = y1 - y0;
len += Math.Sqrt(dx * dx + dy * dy);
x0 = x1;
y0 = y1;
}
return(len);
}
public void Filter(CoordinateSequence seq, int index)
{
if (index == 0)
{
return;
}
var p0 = seq.GetCoordinate(index - 1);
var p1 = seq.GetCoordinate(index);
var midPt = new Coordinate(
(p0.X + p1.X) / 2,
(p0.Y + p1.Y) / 2);
minPtDist.Initialize();
DistanceToPointFinder.ComputeDistance(geom, midPt, minPtDist);
maxPtDist.SetMaximum(minPtDist);
}
public void Filter(CoordinateSequence seq, int i)
{
if (i <= 0)
{
return;
}
// extract LineSegment
var p0 = seq.GetCoordinate(i - 1);
var p1 = seq.GetCoordinate(i);
bool isBorder = Intersects(_envelope, p0, p1) && !ContainsProperly(_envelope, p0, p1);
if (isBorder)
{
var seg = new LineSegment(p0, p1);
_segments.Add(seg);
}
}
/// <summary>
/// Tests whether a point lies on the line defined by a list of
/// coordinates.
/// </summary>
/// <param name="p">The point to test</param>
/// <param name="line">The line coordinates</param>
/// <returns>
/// <c>true</c> if the point is a vertex of the line or lies in the interior
/// of a line segment in the line
/// </returns>
public static bool IsOnLine(Coordinate p, CoordinateSequence line)
{
var lineIntersector = new RobustLineIntersector();
var p0 = line.CreateCoordinate();
var p1 = p0.Copy();
int n = line.Count;
for (int i = 1; i < n; i++)
{
line.GetCoordinate(i - 1, p0);
line.GetCoordinate(i, p1);
lineIntersector.ComputeIntersection(p, p0, p1);
if (lineIntersector.HasIntersection)
{
return(true);
}
}
return(false);
}
private void gatherDim4(CoordinateSequence cs, Dictionary <Coordinate, Double> map)
{
if (cs.Dimension == 4)
{
for (int i = 0; i < cs.Count; i++)
{
map.TryAdd(cs.GetCoordinate(i), cs.GetOrdinate(i, 3));
}
}
}
/// <summary>
///
/// </summary>
/// <param name="seq0"></param>
/// <param name="seq1"></param>
/// <returns></returns>
public bool HasIntersection(CoordinateSequence seq0, CoordinateSequence seq1)
{
for (int i = 1; i < seq0.Count && !_hasIntersection; i++)
{
seq0.GetCoordinate(i - 1, pt00);
seq0.GetCoordinate(i, pt01);
for (int j = 1; j < seq1.Count && !_hasIntersection; j++)
{
seq1.GetCoordinate(j - 1, pt10);
seq1.GetCoordinate(j, pt11);
li.ComputeIntersection(pt00, pt01, pt10, pt11);
if (li.HasIntersection)
{
_hasIntersection = true;
}
}
}
return(_hasIntersection);
}
/// <summary>
/// Determines the <see cref="Geometries.Location"/> of a point in a ring.
/// </summary>
/// <param name="p">The point to test</param>
/// <param name="ring">A coordinate sequence forming a ring</param>
/// <returns>The location of the point in the ring</returns>
public static Location LocatePointInRing(Coordinate p, CoordinateSequence ring)
{
var counter = new RayCrossingCounter(p);
var p1 = ring.CreateCoordinate();
var p2 = ring.CreateCoordinate();
int count = ring.Count;
for (int i = 1; i < count; i++)
{
ring.GetCoordinate(i, p1);
ring.GetCoordinate(i - 1, p2);
counter.CountSegment(p1, p2);
if (counter.IsOnSegment)
{
return(counter.Location);
}
}
return(counter.Location);
}
/**
* Computes an average normal vector from a list of polygon coordinates.
* Uses Newell's method, which is based
* on the fact that the vector with components
* equal to the areas of the projection of the polygon onto
* the Cartesian axis planes is normal.
*
* @param seq the sequence of coordinates for the polygon
* @return a normal vector
*/
private static Vector3D AverageNormal(CoordinateSequence seq)
{
int n = seq.Count;
var sum = new CoordinateZ(0, 0, 0);
var p1 = new CoordinateZ(0, 0, 0);
var p2 = new CoordinateZ(0, 0, 0);
for (int i = 0; i < n - 1; i++)
{
seq.GetCoordinate(i, p1);
seq.GetCoordinate(i + 1, p2);
sum.X += (p1.Y - p2.Y) * (p1.Z + p2.Z);
sum.Y += (p1.Z - p2.Z) * (p1.X + p2.X);
sum.Z += (p1.X - p2.X) * (p1.Y + p2.Y);
}
sum.X /= n;
sum.Y /= n;
sum.Z /= n;
var norm = Vector3D.Create(sum).Normalize();
return(norm);
}
private Coordinate[] ReducePointwise(CoordinateSequence coordinates)
{
var coordReduce = new Coordinate[coordinates.Count];
// copy coordinates and reduce
for (int i = 0; i < coordinates.Count; i++)
{
var coord = coordinates.GetCoordinate(i).Copy();
_targetPm.MakePrecise(coord);
coordReduce[i] = coord;
}
return(coordReduce);
}
// Use map to restore M values on the coordinate array
private CoordinateSequence restoreDim4(CoordinateSequence cs, Dictionary <Coordinate, Double> map)
{
CoordinateSequence seq = new PackedCoordinateSequenceFactory(PackedCoordinateSequenceFactory.PackedType.Double).Create(cs.Count, 4);
for (int i = 0; i < cs.Count; i++)
{
seq.SetOrdinate(i, 0, cs.GetOrdinate(i, 0));
seq.SetOrdinate(i, 1, cs.GetOrdinate(i, 1));
seq.SetOrdinate(i, 2, cs.GetOrdinate(i, 2));
Double d = map[cs.GetCoordinate(i)];
seq.SetOrdinate(i, 3, d == null ? Double.NaN : d);
}
return(seq);
}
protected bool IsAllCoordsEqual(CoordinateSequence seq, Coordinate coord)
{
for (int i = 0; i < seq.Count; i++)
{
if (!coord.Equals(seq.GetCoordinate(i)))
{
return(false);
}
if (coord.X != seq.GetOrdinate(i, 0))
{
return(false);
}
if (coord.Y != seq.GetOrdinate(i, 1))
{
return(false);
}
if (seq.HasZ)
{
if (coord.Z != seq.GetZ(i))
{
return(false);
}
}
if (seq.HasM)
{
if (coord.M != seq.GetM(i))
{
return(false);
}
}
if (seq.Dimension > 2)
{
if (coord[2] != seq.GetOrdinate(i, 2))
{
return(false);
}
}
if (seq.Dimension > 3)
{
if (coord[3] != seq.GetOrdinate(i, 3))
{
return(false);
}
}
}
return(true);
}
private Coordinate[] ReduceCompress(CoordinateSequence coordinates)
{
var noRepeatCoordList = new CoordinateList();
// copy coordinates and reduce
for (int i = 0; i < coordinates.Count; i++)
{
var coord = coordinates.GetCoordinate(i).Copy();
_targetPm.MakePrecise(coord);
noRepeatCoordList.Add(coord, false);
}
// remove repeated points, to simplify returned geometry as much as possible
var noRepeatCoords = noRepeatCoordList.ToCoordinateArray();
return(noRepeatCoords);
}
public void Filter(CoordinateSequence seq, int i)
{
if (seq == null)
{
throw new ArgumentNullException();
}
if (seq.Count == 1)
{
return;
}
if (i > seq.Count - 2)
{
return;
}
LineSegment currentSegment;
SpikeFix spikeFix;
int index;
if (i == 0)
{
currentSegment = new LineSegment(seq.GetCoordinate(0), seq.GetCoordinate(1));
if (IsClosed(seq))
{
_lastSegment = new LineSegment(seq.GetCoordinate(seq.Count - 2), seq.GetCoordinate(0));
spikeFix = CheckSpike(_lastSegment, currentSegment);
if (spikeFix != SpikeFix.NoSpike)
{
index = spikeFix == SpikeFix.First ? seq.Count - 2 : 1;
FixSpike(seq, seq.Count - 1, index);
FixSpike(seq, 0, index);
_changed = true;
}
}
_lastSegment = currentSegment;
return;
}
currentSegment = new LineSegment(_lastSegment.P1, seq.GetCoordinate(i + 1));
spikeFix = CheckSpike(_lastSegment, currentSegment);
if (spikeFix != SpikeFix.NoSpike)
{
index = i + (int)spikeFix;
FixSpike(seq, i, index);
_changed = true;
}
_lastSegment = new LineSegment(seq.GetCoordinate(i), seq.GetCoordinate(i + 1));
}
private static void DoTest(CoordinateSequence forward, CoordinateSequence reversed)
{
const double eps = 1e-12;
Assert.AreEqual(forward.Count, reversed.Count, "Coordinate sequences don't have same size");
Assert.AreEqual(forward.Ordinates, reversed.Ordinates, "Coordinate sequences don't serve same ordinate values");
var ordinates = ToOrdinateArray(forward.Ordinates);
int j = forward.Count;
for (int i = 0; i < forward.Count; i++)
{
j--;
foreach (var ordinate in ordinates)
{
Assert.AreEqual(forward.GetOrdinate(i, ordinate), reversed.GetOrdinate(j, ordinate), eps, string.Format("{0} values are not within tolerance", ordinate));
}
var cf = forward.GetCoordinate(i);
var cr = reversed.GetCoordinate(j);
Assert.IsFalse(ReferenceEquals(cf, cr), "Coordinate sequences deliver same coordinate instances");
Assert.IsTrue(cf.Equals(cr), "Coordinate sequences do not provide equal coordinates");
}
}
/// <summary>
/// Computes whether a ring defined by an <see cref="CoordinateSequence"/> is
/// oriented counter-clockwise.
/// <list type="Bullet">
/// <item>The list of points is assumed to have the first and last points equal.</item>
/// <item>This will handle coordinate lists which contain repeated points.</item>
/// </list>
/// This algorithm is <b>only</b> guaranteed to work with valid rings.If the
/// ring is invalid(e.g.self-crosses or touches), the computed result may not
/// be correct.
/// </summary>
/// <param name="ring">A <c>CoordinateSequence</c>s forming a ring.</param>
/// <returns><c>true</c> if the ring is oriented counter-clockwise.</returns>
/// <exception cref="ArgumentException">Thrown if there are too few points to determine orientation (< 4)</exception>
public static bool IsCCW(CoordinateSequence ring)
{
// # of points without closing endpoint
int nPts = ring.Count - 1;
// sanity check
if (nPts < 3)
{
throw new ArgumentException(
"Ring has fewer than 4 points, so orientation cannot be determined",
nameof(ring));
}
// find highest point
var hiPt = ring.GetCoordinate(0);
int hiIndex = 0;
for (int i = 1; i <= nPts; i++)
{
var p = ring.GetCoordinate(i);
if (p.Y > hiPt.Y)
{
hiPt = ring.GetCoordinate(i);
hiIndex = i;
}
}
// find distinct point before highest point
Coordinate prev;
int iPrev = hiIndex;
do
{
iPrev = iPrev - 1;
if (iPrev < 0)
{
iPrev = nPts;
}
prev = ring.GetCoordinate(iPrev);
} while (prev.Equals2D(hiPt) && iPrev != hiIndex);
// find distinct point after highest point
Coordinate next;
int iNext = hiIndex;
do
{
iNext = (iNext + 1) % nPts;
next = ring.GetCoordinate(iNext);
} while (next.Equals2D(hiPt) && iNext != hiIndex);
/**
* This check catches cases where the ring contains an A-B-A configuration
* of points. This can happen if the ring does not contain 3 distinct points
* (including the case where the input array has fewer than 4 elements), or
* it contains coincident line segments.
*/
if (prev.Equals2D(hiPt) || next.Equals2D(hiPt) || prev.Equals2D(next))
{
return(false);
}
var disc = Index(prev, hiPt, next);
/**
* If disc is exactly 0, lines are collinear. There are two possible cases:
* (1) the lines lie along the x axis in opposite directions (2) the lines
* lie on top of one another
*
* (1) is handled by checking if next is left of prev ==> CCW (2) will never
* happen if the ring is valid, so don't check for it (Might want to assert
* this)
*/
bool isCCW;
if (disc == OrientationIndex.Collinear)
{
// polygon is CCW if previous x is right of next x
isCCW = (prev.X > next.X);
}
else
{
// if area is positive, points are ordered CCW
isCCW = (disc > 0);
}
return(isCCW);
}
/**
* Returns a coordinateSequence free of Coordinates with X or Y NaN value,
* and if desired, free of duplicated coordinates. makeSequenceValid keeps
* the original dimension of input sequence.
*
* @param sequence input sequence of coordinates
* @param preserveDuplicateCoord if duplicate coordinates must be preserved
* @param close if the sequence must be closed
* @return a new CoordinateSequence with valid XY values
*/
private static CoordinateSequence makeSequenceValid(CoordinateSequence sequence,
bool preserveDuplicateCoord, bool close)
{
int dim = sequence.Dimension;
// we Add 1 to the sequence size for the case where we have to close the linear ring
double[] array = new double[(sequence.Count + 1) * sequence.Dimension];
bool modified = false;
int count = 0;
// Iterate through coordinates, skip points with x=NaN, y=NaN or duplicate
for (int i = 0; i < sequence.Count; i++)
{
if (Double.IsNaN(sequence.GetOrdinate(i, 0)) || Double.IsNaN(sequence.GetOrdinate(i, 1)))
{
modified = true;
continue;
}
if (!preserveDuplicateCoord && count > 0 && sequence.GetCoordinate(i).Equals(sequence.GetCoordinate(i - 1)))
{
modified = true;
continue;
}
for (int j = 0; j < dim; j++)
{
array[count * dim + j] = sequence.GetOrdinate(i, j);
if (j == dim - 1)
{
count++;
}
}
}
// Close the sequence if it is not closed and there is already 3 distinct coordinates
if (close && count > 2 && (array[0] != array[(count - 1) * dim] || array[1] != array[(count - 1) * dim + 1]))
{
System.Array.Copy(array, 0, array, count * dim, dim);
modified = true;
count++;
}
// Close z, m dimension if needed
if (close && count > 3 && dim > 2)
{
for (int d = 2; d < dim; d++)
{
if (array[(count - 1) * dim + d] != array[d])
{
modified = true;
}
array[(count - 1) * dim + d] = array[d];
}
}
if (modified)
{
double[] shrinkedArray = new double[count * dim];
System.Array.Copy(array, 0, shrinkedArray, 0, count * dim);
return(PackedCoordinateSequenceFactory.DoubleFactory.Create(shrinkedArray, dim));
}
else
{
return(sequence);
}
}
/// <summary>
/// Gets the coordinate at the given index
/// </summary>
/// <param name="index">The index</param>
/// <returns>The coordinate at the given index</returns>
public Coordinate GetCoordinate(int index)
{
return(_pts.GetCoordinate(_start + index));
}
/// <summary>
/// Tests for equality using all supported accessors,
/// to provides test coverage for them.
/// </summary>
/// <param name="seq"></param>
/// <param name="coords"></param>
/// <returns></returns>
protected bool IsEqual(CoordinateSequence seq, Coordinate[] coords)
{
if (seq.Count != coords.Length)
{
return(false);
}
// carefully get coordinate of the same type as the sequence
var p = seq.CreateCoordinate();
for (int i = 0; i < seq.Count; i++)
{
if (!coords[i].Equals(seq.GetCoordinate(i)))
{
return(false);
}
// Ordinate named getters
if (!coords[i].X.Equals(seq.GetX(i)))
{
return(false);
}
if (!coords[i].Y.Equals(seq.GetY(i)))
{
return(false);
}
if (seq.HasZ)
{
if (!coords[i].Z.Equals(seq.GetZ(i)))
{
return(false);
}
}
if (seq.HasM)
{
if (!coords[i].M.Equals(seq.GetM(i)))
{
return(false);
}
}
// Ordinate indexed getters
if (!coords[i].X.Equals(seq.GetOrdinate(i, 0)))
{
return(false);
}
if (!coords[i].Y.Equals(seq.GetOrdinate(i, 1)))
{
return(false);
}
if (seq.Dimension > 2)
{
if (!coords[i][2].Equals(seq.GetOrdinate(i, 2)))
{
return(false);
}
}
if (seq.Dimension > 3)
{
if (!coords[i][3].Equals(seq.GetOrdinate(i, 3)))
{
return(false);
}
}
// Coordinate getter
seq.GetCoordinate(i, p);
if (!coords[i].X.Equals(p.X))
{
return(false);
}
if (!coords[i].Y.Equals(p.Y))
{
return(false);
}
if (seq.HasZ)
{
if (!coords[i].Z.Equals(p.Z))
{
return(false);
}
}
if (seq.HasM)
{
if (!coords[i].M.Equals(p.M))
{
return(false);
}
}
}
return(true);
}
private static bool IsClosed(CoordinateSequence seq)
{
return(seq.GetCoordinate(seq.Count - 1).Equals2D(seq.GetCoordinate(0)));
}
/// <summary>
/// Tests if a ring defined by a <see cref="CoordinateSequence"/> is
/// oriented counter-clockwise.
/// <list type="bullet">
/// <item><description>The list of points is assumed to have the first and last points equal.</description></item>
/// <item><description>This handles coordinate lists which contain repeated points.</description></item>
/// <item><description>This handles rings which contain collapsed segments (in particular, along the top of the ring).</description></item>
/// </list>
/// This algorithm is guaranteed to work with valid rings.
/// It also works with "mildly invalid" rings
/// which contain collapsed(coincident) flat segments along the top of the ring.
/// If the ring is "more" invalid (e.g.self-crosses or touches),
/// the computed result may not be correct.
/// </summary>
/// <param name="ring">A <c>CoordinateSequence</c>s forming a ring (with first and last point identical).</param>
/// <returns><c>true</c> if the ring is oriented counter-clockwise.</returns>
/// <exception cref="ArgumentException">Thrown if there are too few points to determine orientation (< 4)</exception>
public static bool IsCCW(CoordinateSequence ring)
{
// # of points without closing endpoint
int nPts = ring.Count - 1;
// sanity check
if (nPts < 3)
{
throw new ArgumentException(
"Ring has fewer than 4 points, so orientation cannot be determined", nameof(ring));
}
/*
* Find first highest point after a lower point, if one exists
* (e.g. a rising segment)
* If one does not exist, hiIndex will remain 0
* and the ring must be flat.
* Note this relies on the convention that
* rings have the same start and end point.
*/
var upHiPt = ring.GetCoordinate(0);
double prevY = upHiPt.Y;
Coordinate upLowPt = null;
int iUpHi = 0;
for (int i = 1; i <= nPts; i++)
{
double py = ring.GetOrdinate(i, Ordinate.Y);
/*
* If segment is upwards and endpoint is higher, record it
*/
if (py > prevY && py >= upHiPt.Y)
{
upHiPt = ring.GetCoordinate(i);
iUpHi = i;
upLowPt = ring.GetCoordinate(i - 1);
}
prevY = py;
}
/*
* Check if ring is flat and return default value if so
*/
if (iUpHi == 0)
{
return(false);
}
/*
* Find the next lower point after the high point
* (e.g. a falling segment).
* This must exist since ring is not flat.
*/
int iDownLow = iUpHi;
do
{
iDownLow = (iDownLow + 1) % nPts;
} while (iDownLow != iUpHi && ring.GetOrdinate(iDownLow, Ordinate.Y) == upHiPt.Y);
var downLowPt = ring.GetCoordinate(iDownLow);
int iDownHi = iDownLow > 0 ? iDownLow - 1 : nPts - 1;
var downHiPt = ring.GetCoordinate(iDownHi);
/*
* Two cases can occur:
* 1) the hiPt and the downPrevPt are the same.
* This is the general position case of a "pointed cap".
* The ring orientation is determined by the orientation of the cap
* 2) The hiPt and the downPrevPt are different.
* In this case the top of the cap is flat.
* The ring orientation is given by the direction of the flat segment
*/
if (upHiPt.Equals2D(downHiPt))
{
/*
* Check for the case where the cap has configuration A-B-A.
* This can happen if the ring does not contain 3 distinct points
* (including the case where the input array has fewer than 4 elements), or
* it contains coincident line segments.
*/
if (upLowPt.Equals2D(upHiPt) || downLowPt.Equals2D(upHiPt) || upLowPt.Equals2D(downLowPt))
{
return(false);
}
/*
* It can happen that the top segments are coincident.
* This is an invalid ring, which cannot be computed correctly.
* In this case the orientation is 0, and the result is false.
*/
var index = Index(upLowPt, upHiPt, downLowPt);
return(index == OrientationIndex.CounterClockwise);
}
else
{
/*
* Flat cap - direction of flat top determines orientation
*/
double delX = downHiPt.X - upHiPt.X;
return(delX < 0);
}
}
