/// <summary>
/// Add an edge to the polygon or polyline.
/// </summary>
/// <param name="g">The geod_geodesic object specifying the ellipsoid.</param>
/// <param name="p">The geod_polygon object specifying the polygon.</param>
/// <param name="azi">The azimuth at current point (degrees).</param>
/// <param name="s">The distance from current point to next point (meters).</param>
/// <remarks>
/// g and p must have been initialized with calls to geod_init() and
/// geod_polygon_init(), respectively. The same g must be used for all the
/// points and edges in a polygon. azi should be in the range
/// [-540deg, 540deg). This does nothing if no points have been
/// added yet. The lat and lon fields of p give the location of
/// the new vertex.
/// </remarks>
public void geod_polygon_addedge(geod_geodesic g, double azi, double s)
{
if (num != 0)
{ // Do nothing is num is zero
double lat, lon, S12 = 0, dummy;
if (polyline)
{
g.geod_gendirect(this.lat, this.lon, azi, GEOD.LONG_UNROLL, s, GEOD.LATITUDE | GEOD.LONGITUDE, out lat, out lon, out dummy, out dummy, out dummy, out dummy, out dummy, out dummy);
}
else
{
g.geod_gendirect(this.lat, this.lon, azi, GEOD.LONG_UNROLL, s, GEOD.LATITUDE | GEOD.LONGITUDE | GEOD.AREA, out lat, out lon, out dummy, out dummy, out dummy, out dummy, out dummy, out S12);
}
accadd(P, s);
if (!polyline)
{
accadd(A, S12);
crossings += transitdirect(this.lon, lon);
}
this.lat = lat; this.lon = lon;
++num;
}
}
/// <summary>
/// Return the results assuming a tentative final test point is added via an
/// azimuth and distance; 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 geod_polygon_addedge() and
/// geod_polygon_compute() are used.
/// </summary>
/// <param name="g">The geod_geodesic object specifying the ellipsoid.</param>
/// <param name="p">The geod_polygon object specifying the polygon.</param>
/// <param name="azi">The azimuth at current point (degrees).</param>
/// <param name="s">The distance from current point to final test point (meters).</param>
/// <param name="reverse">If set <b>true</b> then clockwise (instead of counter-clockwise)
/// traversal counts as a positive area.</param>
/// <param name="sign">If set <b>true</b> 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.</param>
/// <param name="pA">The area of the polygon (square meters); only set if polyline is set <b>true</b>
/// in the call to geod_polygon_init().</param>
/// <param name="pP">The perimeter of the polygon or length of the polyline (meters).</param>
/// <returns>The number of points.</returns>
/// <remarks>
/// azi should be in the range [-540deg, 540deg).
/// </remarks>
public int geod_polygon_testedge(geod_geodesic g, double azi, double s, bool reverse, bool sign, out double pA, out double pP)
{
pP = pA = NaN;
int num = this.num + 1;
if (num == 1)
{
return(0); // we don't have a starting point!
}
double perimeter = P[0] + s;
if (polyline)
{
pP = perimeter;
return(num);
}
double tempsum = A[0];
int crossings = this.crossings;
{
double lat, lon, s12, S12, dummy;
g.geod_gendirect(this.lat, this.lon, azi, GEOD.LONG_UNROLL, s, GEOD.LATITUDE | GEOD.LONGITUDE | GEOD.AREA, out lat, out lon, out dummy, out dummy, out dummy, out dummy, out dummy, out S12);
tempsum += S12;
crossings += transitdirect(this.lon, lon);
g.geod_geninverse(lat, lon, lat0, lon0, GEOD.DISTANCE | GEOD.AREA, out s12, out dummy, out dummy, out dummy, out dummy, out dummy, out S12);
perimeter += s12;
tempsum += S12;
crossings += transit(lon, lon0);
}
double area0 = 4 * pi * g.c2;
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;
}
}
pP = perimeter;
pA = 0 + tempsum;
return(num);
}
/// <summary>
/// Return the results assuming a tentative final test point is added via an
/// azimuth and distance; 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 geod_polygon_addedge() and
/// geod_polygon_compute() are used.
/// </summary>
/// <param name="g">The geod_geodesic object specifying the ellipsoid.</param>
/// <param name="p">The geod_polygon object specifying the polygon.</param>
/// <param name="azi">The azimuth at current point (degrees).</param>
/// <param name="s">The distance from current point to final test point (meters).</param>
/// <param name="reverse">If set <b>true</b> then clockwise (instead of counter-clockwise)
/// traversal counts as a positive area.</param>
/// <param name="sign">If set <b>true</b> 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.</param>
/// <param name="pA">The area of the polygon (square meters); only set if polyline is set <b>true</b>
/// in the call to geod_polygon_init().</param>
/// <param name="pP">The perimeter of the polygon or length of the polyline (meters).</param>
/// <returns>The number of points.</returns>
/// <remarks>
/// azi should be in the range [-540deg, 540deg).
/// </remarks>
public int geod_polygon_testedge(geod_geodesic g, double azi, double s, bool reverse, bool sign, out double pA, out double pP)
{
pP=pA=NaN;
int num=this.num+1;
if(num==1) return 0; // we don't have a starting point!
double perimeter=P[0]+s;
if(polyline)
{
pP=perimeter;
return num;
}
double tempsum=A[0];
int crossings=this.crossings;
{
double lat, lon, s12, S12, dummy;
g.geod_gendirect(this.lat, this.lon, azi, GEOD.LONG_UNROLL, s, GEOD.LATITUDE|GEOD.LONGITUDE|GEOD.AREA, out lat, out lon, out dummy, out dummy, out dummy, out dummy, out dummy, out S12);
tempsum+=S12;
crossings+=transitdirect(this.lon, lon);
g.geod_geninverse(lat, lon, lat0, lon0, GEOD.DISTANCE|GEOD.AREA, out s12, out dummy, out dummy, out dummy, out dummy, out dummy, out S12);
perimeter+=s12;
tempsum+=S12;
crossings+=transit(lon, lon0);
}
double area0=4*pi*g.c2;
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;
}
pP=perimeter;
pA=0+tempsum;
return num;
}
/// <summary>
/// Add an edge to the polygon or polyline.
/// </summary>
/// <param name="g">The geod_geodesic object specifying the ellipsoid.</param>
/// <param name="p">The geod_polygon object specifying the polygon.</param>
/// <param name="azi">The azimuth at current point (degrees).</param>
/// <param name="s">The distance from current point to next point (meters).</param>
/// <remarks>
/// g and p must have been initialized with calls to geod_init() and
/// geod_polygon_init(), respectively. The same g must be used for all the
/// points and edges in a polygon. azi should be in the range
/// [-540deg, 540deg). This does nothing if no points have been
/// added yet. The lat and lon fields of p give the location of
/// the new vertex.
/// </remarks>
public void geod_polygon_addedge(geod_geodesic g, double azi, double s)
{
if(num!=0)
{ // Do nothing is num is zero
double lat, lon, S12=0, dummy;
if(polyline) g.geod_gendirect(this.lat, this.lon, azi, GEOD.LONG_UNROLL, s, GEOD.LATITUDE|GEOD.LONGITUDE, out lat, out lon, out dummy, out dummy, out dummy, out dummy, out dummy, out dummy);
else g.geod_gendirect(this.lat, this.lon, azi, GEOD.LONG_UNROLL, s, GEOD.LATITUDE|GEOD.LONGITUDE|GEOD.AREA, out lat, out lon, out dummy, out dummy, out dummy, out dummy, out dummy, out S12);
accadd(P, s);
if(!polyline)
{
accadd(A, S12);
crossings+=transitdirect(this.lon, lon);
}
this.lat=lat; this.lon=lon;
++num;
}
}
