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/******************************************************************************
*
* Project: OGR
* Purpose: Geo-computations
* Author: Even Rouault, even dot rouault at spatialys.com
*
******************************************************************************
* Copyright (c) 2008-2010, Even Rouault <even dot rouault at spatialys.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
****************************************************************************/
#include "ogr_geo_utils.h"
#include "cpl_port.h"
#include "cpl_error.h"
constexpr double RAD2METER = (180.0 / M_PI) * 60.0 * 1852.0;
constexpr double METER2RAD = 1.0 / RAD2METER;
constexpr double DEG2RAD = M_PI / 180.0;
constexpr double RAD2DEG = 1.0 / DEG2RAD;
static double OGR_Safe_acos(double x)
{
if (x > 1)
x = 1;
else if (x < -1)
x = -1;
return acos(x);
}
/************************************************************************/
/* OGR_GreatCircle_Distance() */
/************************************************************************/
double OGR_GreatCircle_Distance(double LatA_deg, double LonA_deg,
double LatB_deg, double LonB_deg)
{
const double cosP = cos((LonB_deg - LonA_deg) * DEG2RAD);
const double LatA_rad = LatA_deg * DEG2RAD;
const double LatB_rad = LatB_deg * DEG2RAD;
const double cosa = cos(LatA_rad);
const double sina = sin(LatA_rad);
const double cosb = cos(LatB_rad);
const double sinb = sin(LatB_rad);
const double cos_angle = sina * sinb + cosa * cosb * cosP;
return OGR_Safe_acos(cos_angle) * RAD2METER;
}
/************************************************************************/
/* OGR_GreatCircle_InitialHeading() */
/************************************************************************/
double OGR_GreatCircle_InitialHeading(double LatA_deg, double LonA_deg,
double LatB_deg, double LonB_deg)
{
if (fabs(LatA_deg - 90) < 1e-10 || fabs(LatB_deg + 90) < 1e-10)
{
return 180;
}
else if (fabs(LatA_deg + 90) < 1e-10 || fabs(LatB_deg - 90) < 1e-10)
{
return 0;
}
else if (fabs(fmod(LonA_deg - LonB_deg, 360.0)) < 1e-10 &&
fabs(LatA_deg - LatB_deg) < 1e-10)
{
return 0; // Arbitrary number
}
else if (fabs(LatA_deg) < 1e-10 && fabs(LatB_deg) < 1e-10)
{
return (LonB_deg > LonA_deg) ? 90.0 : 270.0;
}
else if (fabs(fmod(LonA_deg - LonB_deg, 360.0)) < 1e-10)
{
return (LatA_deg > LatB_deg) ? 180.0 : 0.0;
}
else
{
const double LatA_rad = LatA_deg * DEG2RAD;
const double LatB_rad = LatB_deg * DEG2RAD;
const double cos_LatA = cos(LatA_rad);
const double sin_LatA = sin(LatA_rad);
const double diffG = (LonA_deg - LonB_deg) * DEG2RAD;
const double cos_diffG = cos(diffG);
const double sin_diffG = sin(diffG);
const double denom = sin_LatA * cos_diffG - cos_LatA * tan(LatB_rad);
if (denom == 0.0)
{
// Can be the the case if Lat_A = -Lat_B and abs(LonA - LonB) = 180
return 0.0;
}
double track = atan(sin_diffG / denom) * RAD2DEG;
if (denom > 0.0)
{
track = 180 + track;
}
else if (track < 0)
{
track = 360 + track;
}
return track;
}
}
/************************************************************************/
/* OGR_GreatCircle_ExtendPosition() */
/************************************************************************/
int OGR_GreatCircle_ExtendPosition(double dfLatA_deg, double dfLonA_deg,
double dfDistance, double dfHeadingInA,
double *pdfLatB_deg, double *pdfLonB_deg)
{
const double dfHeadingRad = dfHeadingInA * DEG2RAD;
const double cos_Heading = cos(dfHeadingRad);
const double sin_Heading = sin(dfHeadingRad);
const double dfDistanceRad = dfDistance * METER2RAD;
const double cos_Distance = cos(dfDistanceRad);
const double sin_Distance = sin(dfDistanceRad);
const double dfLatA_rad = dfLatA_deg * DEG2RAD;
const double cos_complement_LatA = sin(dfLatA_rad);
const double sin_complement_LatA = cos(dfLatA_rad);
if (dfDistance == 0.0)
{
*pdfLatB_deg = dfLatA_deg;
*pdfLonB_deg = dfLonA_deg;
return 1;
}
if (fabs(dfLatA_deg) >= 90.0)
{
*pdfLatB_deg = dfLatA_deg;
*pdfLonB_deg = dfLonA_deg;
return 0;
}
if (fabs(sin_Heading) < 1e-8)
{
*pdfLonB_deg = dfLonA_deg;
if (fabs(fmod(dfHeadingInA + 360.0, 360.0)) < 1e-8)
{
*pdfLatB_deg = dfLatA_deg + dfDistanceRad * RAD2DEG;
}
else
{
*pdfLatB_deg = dfLatA_deg - dfDistanceRad * RAD2DEG;
}
return 1;
}
if (fabs(cos_complement_LatA) < 1e-8 && fabs(cos_Heading) < 1e-8)
{
*pdfLatB_deg = dfLatA_deg;
if (fabs(dfHeadingInA - 90.0) < 1e-8)
{
*pdfLonB_deg = dfLonA_deg + dfDistanceRad * RAD2DEG;
}
else
{
*pdfLonB_deg = dfLonA_deg - dfDistanceRad * RAD2DEG;
}
return 1;
}
const double cos_complement_latB =
cos_Distance * cos_complement_LatA +
sin_Distance * sin_complement_LatA * cos_Heading;
const double complement_latB = OGR_Safe_acos(cos_complement_latB);
const double dfDenomin = sin(complement_latB) * sin_complement_LatA;
if (dfDenomin == 0.0)
CPLDebug("OGR", "OGR_GreatCircle_Distance: dfDenomin == 0.0");
const double Cos_dG =
(cos_Distance - cos_complement_latB * cos_complement_LatA) / dfDenomin;
*pdfLatB_deg = 90 - complement_latB * RAD2DEG;
const double dG_deg = OGR_Safe_acos(Cos_dG) * RAD2DEG;
if (sin_Heading < 0)
*pdfLonB_deg = dfLonA_deg - dG_deg;
else
*pdfLonB_deg = dfLonA_deg + dG_deg;
if (*pdfLonB_deg > 180)
*pdfLonB_deg -= 360;
else if (*pdfLonB_deg <= -180)
*pdfLonB_deg += 360;
return 1;
}
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