bool _stdcall PtIsOnArc( const LLPoint & llArcCenter, double dArcRadius,
double dArcStartAzimuth, double dArcEndAzimuth, int nArcDirection,
const LLPoint & llTestPt, int & bOnArc )
{
InverseResult invResult;
if(!DistVincenty(llArcCenter, llTestPt, invResult))
return false;
double dDist = invResult.distance;
double dCrs = invResult.azimuth;
bOnArc = false;
if(fabs(dDist - dArcRadius) > 0.5e-3) //Tol())
bOnArc = false;
else {
double dArcExtent = GetArcExtent(dArcStartAzimuth, dArcEndAzimuth, nArcDirection, Tol());
if(dArcExtent == M_2PI)
bOnArc = true;
else
{
double dSubExtent = GetArcExtent(dArcStartAzimuth, dCrs, nArcDirection, Tol());
if(nArcDirection > 0) {
if(dSubExtent <= dArcExtent)
bOnArc = true;
} else {
if(dSubExtent >= dArcExtent)
bOnArc = true;
}
}
}
return true;
}
bool PtIsOnArc(const LLPoint &llArcCenter, double dArcRadius,
double dArcStartAzimuth, double dArcEndAzimuth, int nArcDirection,
const LLPoint &llTestPt, int &bOnArc)
{
InverseResult invResult;
if (!DistVincenty(llArcCenter, llTestPt, invResult))
return false;
bOnArc = false;
if (fabs(invResult.distance - dArcRadius) <= 0.5e-3)
{
const double dSubtendedAng1 = GetArcExtent(dArcStartAzimuth, dArcEndAzimuth, nArcDirection, kTol);
if (dSubtendedAng1 == M_2PI)
bOnArc = true;
else
{
const double dSubtendedAng2 = GetArcExtent(dArcStartAzimuth, invResult.azimuth,
nArcDirection, kTol);
if (nArcDirection > 0)
{
if (dSubtendedAng2 <= dSubtendedAng1)
bOnArc = true;
}
else
{
if (dSubtendedAng2 >= dSubtendedAng1)
bOnArc = true;
}
}
}
return true;
}
double DiscretizedArcLength(const LLPoint ¢er, double dRadius,
double dStartCrs, double dEndCrs,
int nOrient, int nSegments, double dTol)
{
nSegments = clamp(nSegments, 1, 128);
double dError = 0.0;
double dArcLength = 0.0;
double dOldArcLength = 0.0;
const double dSubtendedAngle = GetArcExtent(dStartCrs, dEndCrs, nOrient, dTol);
// with k equal to 0 then there will only be nSegments subsegments calculated.
// need to figure out how to make this flexible based on the value in dRadius.
// Bigger radius need more segments than 16 and smaller segments need less.
// For now 16 is enough to pass the 8260.54A test case.
int k = 0;
while (k == 0 || ((dError > kTol) && (k <= 0)))
{
const double dTheta = dSubtendedAngle / nSegments;
const double dAltitude = 0.0;
dArcLength = 0.0;
for (int i = 0; i < nSegments; i++)
{
const double theta = dStartCrs + i * dTheta;
const LLPoint p1 = DestVincenty(center, theta, dRadius);
const LLPoint p2 = DestVincenty(center, theta + 0.5 * dTheta, dRadius);
const LLPoint p3 = DestVincenty(center, theta + dTheta, dRadius);
const VMath::Vector3 v1 = ECEF(p1, dAltitude);
const VMath::Vector3 v2 = ECEF(p2, dAltitude);
const VMath::Vector3 v3 = ECEF(p3, dAltitude);
const VMath::Vector3 vChord1 = v2 - v1;
const VMath::Vector3 vChord2 = v2 - v3;
const double x1 = VMath::Vector3::Length(vChord1); //v2 - v1);
const double x2 = VMath::Vector3::Length(vChord2); //v2 - v3);
const double d = VMath::Vector3::Dot(vChord1, vChord2);
if (IsNearZero(x1, kTol) && IsNearZero(x2, kTol) && IsNearZero(d, kTol))
{
dArcLength = 0.0;
break;
}
const double xi = d / (x1 * x2);
const double _x1_x2Sq = x1 / x2 - xi;
const double sigma = sqrt(1.0 - (xi * xi));
const double R = (x2 * sqrt((_x1_x2Sq * _x1_x2Sq) + (sigma * sigma))) / (2.0 * sigma);
const double A = 2 * (M_PI - acos(xi));
const double L = R * A;
dArcLength += L;
}
nSegments *= 2;
dError = fabs(dArcLength - dOldArcLength);
dOldArcLength = dArcLength;
k++;
}
return dArcLength;
}
