/**
* Return the results so far.
* <p>
* @param reverse if true then clockwise (instead of counter-clockwise)
* traversal counts as a positive area.
* @param sign if true then return a signed result for the area if
* the polygon is traversed in the "wrong" direction instead of returning
* the area for the rest of the earth.
* @return PolygonResult(<i>num</i>, <i>perimeter</i>, <i>area</i>) where
* <i>num</i> is the number of vertices, <i>perimeter</i> is the perimeter
* of the polygon or the length of the polyline (meters), and <i>area</i>
* is the area of the polygon (meters<sup>2</sup>) or Double.NaN of
* <i>polyline</i> is true in the constructor.
* <p>
* More points can be added to the polygon after this call.
**********************************************************************/
public PolygonResult Compute(bool reverse, bool sign)
{
if (_num < 2)
{
return(new PolygonResult(_num, 0, _polyline ? Double.NaN : 0));
}
if (_polyline)
{
return(new PolygonResult(_num, _perimetersum.Sum(), Double.NaN));
}
GeodesicData g = _earth.Inverse(_lat1, _lon1, _lat0, _lon0, _mask);
Accumulator tempsum = new Accumulator(_areasum);
tempsum.Add(g.GeodesicScale12);
int crossings = _crossings + Transit(_lon1, _lon0);
if ((crossings & 1) != 0)
{
tempsum.Add((tempsum.Sum() < 0 ? 1 : -1) * _area0 / 2);
}
// area is with the clockwise sense. If !reverse convert to
// counter-clockwise convention.
if (!reverse)
{
tempsum.Negate();
}
// If sign put area in (-area0/2, area0/2], else put area in [0, area0)
if (sign)
{
if (tempsum.Sum() > _area0 / 2)
{
tempsum.Add(-_area0);
}
else if (tempsum.Sum() <= -_area0 / 2)
{
tempsum.Add(+_area0);
}
}
else
{
if (tempsum.Sum() >= _area0)
{
tempsum.Add(-_area0);
}
else if (tempsum.Sum() < 0)
{
tempsum.Add(+_area0);
}
}
return
(new PolygonResult(_num, _perimetersum.Sum(g.Distance), 0 + tempsum.Sum()));
}
/**
* Return the results assuming a tentative final test point is added;
* however, the data for the test point is not saved. This lets you report
* a running result for the perimeter and area as the user moves the mouse
* cursor. Ordinary floating point arithmetic is used to accumulate the
* data for the test point; thus the area and perimeter returned are less
* accurate than if AddPoint and Compute are used.
* <p>
* @param lat the latitude of the test point (degrees).
* @param lon the longitude of the test point (degrees).
* @param reverse if true then clockwise (instead of counter-clockwise)
* traversal counts as a positive area.
* @param sign if true then return a signed result for the area if
* the polygon is traversed in the "wrong" direction instead of returning
* the area for the rest of the earth.
* @return PolygonResult(<i>num</i>, <i>perimeter</i>, <i>area</i>) where
* <i>num</i> is the number of vertices, <i>perimeter</i> is the perimeter
* of the polygon or the length of the polyline (meters), and <i>area</i>
* is the area of the polygon (meters<sup>2</sup>) or Double.NaN of
* <i>polyline</i> is true in the constructor.
* <p>
* <i>lat</i> should be in the range [−90°, 90°].
**********************************************************************/
public PolygonResult TestPoint(double lat, double lon,
bool reverse, bool sign)
{
if (_num == 0)
{
return(new PolygonResult(1, 0, _polyline ? Double.NaN : 0));
}
double perimeter = _perimetersum.Sum();
double tempsum = _polyline ? 0 : _areasum.Sum();
int crossings = _crossings;
int num = _num + 1;
for (int i = 0; i < (_polyline ? 1 : 2); ++i)
{
GeodesicData g =
_earth.Inverse(i == 0 ? _lat1 : lat, i == 0 ? _lon1 : lon,
i != 0 ? _lat0 : lat, i != 0 ? _lon0 : lon,
_mask);
perimeter += g.Distance;
if (!_polyline)
{
tempsum += g.GeodesicScale12;
crossings += Transit(i == 0 ? _lon1 : lon,
i != 0 ? _lon0 : lon);
}
}
if (_polyline)
{
return(new PolygonResult(num, perimeter, Double.NaN));
}
if ((crossings & 1) != 0)
{
tempsum += (tempsum < 0 ? 1 : -1) * _area0 / 2;
}
// area is with the clockwise sense. If !reverse convert to
// counter-clockwise convention.
if (!reverse)
{
tempsum *= -1;
}
// If sign put area in (-area0/2, area0/2], else put area in [0, area0)
if (sign)
{
if (tempsum > _area0 / 2)
{
tempsum -= _area0;
}
else if (tempsum <= -_area0 / 2)
{
tempsum += _area0;
}
}
else
{
if (tempsum >= _area0)
{
tempsum -= _area0;
}
else if (tempsum < 0)
{
tempsum += _area0;
}
}
return(new PolygonResult(num, perimeter, 0 + tempsum));
}
