GnomonicProjection.cpp

// SPDX-License-Identifier: LGPL-2.1-or-later
//
// SPDX-FileCopyrightText: 2013 Bernhard Beschow <bbeschow@cs.tu-berlin.de>
//
 
// Local
#include "GnomonicProjection.h"
#include "AbstractProjection_p.h"
 
#include "MarbleDebug.h"
 
// Marble
#include "ViewportParams.h"
#include "GeoDataPoint.h"
#include "GeoDataLineString.h"
#include "GeoDataCoordinates.h"
#include "MarbleGlobal.h"
#include "AzimuthalProjection_p.h"
 
#include <QIcon>
#include <qmath.h>
 
#define SAFE_DISTANCE
 
namespace Marble
{
 
class GnomonicProjectionPrivate : public AzimuthalProjectionPrivate
{
  public:
    explicit GnomonicProjectionPrivate( GnomonicProjection * parent );
 
    Q_DECLARE_PUBLIC( GnomonicProjection )
};
 
GnomonicProjection::GnomonicProjection()
    : AzimuthalProjection( new GnomonicProjectionPrivate( this ) )
{
    setMinLat( minValidLat() );
    setMaxLat( maxValidLat() );
}
 
GnomonicProjection::GnomonicProjection( GnomonicProjectionPrivate *dd )
        : AzimuthalProjection( dd )
{
    setMinLat( minValidLat() );
    setMaxLat( maxValidLat() );
}
 
GnomonicProjection::~GnomonicProjection()
{
}
 
 
GnomonicProjectionPrivate::GnomonicProjectionPrivate( GnomonicProjection * parent )
        : AzimuthalProjectionPrivate( parent )
{
}
 
QString GnomonicProjection::name() const
{
    return QObject::tr( "Gnomonic" );
}
 
QString GnomonicProjection::description() const
{
    return QObject::tr( "<p><b>Gnomonic Projection</b> (\"rectilinear\")</p><p>Applications: Used for displaying panorama photography. Also used for navigation, radio and seismic work.</p>" );
}
 
QIcon GnomonicProjection::icon() const
{
    return QIcon(QStringLiteral(":/icons/map-gnomonic.png"));
}
 
qreal GnomonicProjection::clippingRadius() const
{
    return 1;
}
 
bool GnomonicProjection::screenCoordinates( const GeoDataCoordinates &coordinates,
                                             const ViewportParams *viewport,
                                             qreal &x, qreal &y, bool &globeHidesPoint ) const
{
    const qreal lambda = coordinates.longitude();
    const qreal phi = coordinates.latitude();
    const qreal lambdaPrime = viewport->centerLongitude();
    const qreal phi1 = viewport->centerLatitude();
 
    qreal cosC = qSin( phi1 ) * qSin( phi ) + qCos( phi1 ) * qCos( phi ) * qCos( lambda - lambdaPrime );
 
    if ( cosC <= 0) {
        globeHidesPoint = true;
        return false;
    }
 
    // Let (x, y) be the position on the screen of the placemark..
    x = ( qCos( phi ) * qSin( lambda - lambdaPrime ) ) / cosC;
    y = ( qCos( phi1 ) * qSin( phi ) - qSin( phi1 ) * qCos( phi ) * qCos( lambda - lambdaPrime ) ) / cosC;
 
    x *= viewport->radius() / 2;
    y *= viewport->radius() / 2;
 
    const qint64  radius  = clippingRadius() * viewport->radius();
 
    if (x*x + y*y > radius * radius) {
        globeHidesPoint = true;
        return false;
    }
 
    globeHidesPoint = false;
 
    x += viewport->width() / 2;
    y = viewport->height() / 2 - y;
 
    // Skip placemarks that are outside the screen area
    return !(x < 0 || x >= viewport->width() || y < 0 || y >= viewport->height());
}
 
bool GnomonicProjection::screenCoordinates( const GeoDataCoordinates &coordinates,
                                             const ViewportParams *viewport,
                                             qreal *x, qreal &y,
                                             int &pointRepeatNum,
                                             const QSizeF& size,
                                             bool &globeHidesPoint ) const
{
    pointRepeatNum = 0;
    globeHidesPoint = false;
 
    bool visible = screenCoordinates( coordinates, viewport, *x, y, globeHidesPoint );
 
    // Skip placemarks that are outside the screen area
    if ( *x + size.width() / 2.0 < 0.0 || *x >= viewport->width() + size.width() / 2.0
         || y + size.height() / 2.0 < 0.0 || y >= viewport->height() + size.height() / 2.0 )
    {
        return false;
    }
 
    // This projection doesn't have any repetitions,
    // so the number of screen points referring to the geopoint is one.
    pointRepeatNum = 1;
    return visible;
}
 
 
bool GnomonicProjection::geoCoordinates( const int x, const int y,
                                          const ViewportParams *viewport,
                                          qreal& lon, qreal& lat,
                                          GeoDataCoordinates::Unit unit ) const
{
    const qint64  radius  = viewport->radius();
    // Calculate how many degrees are being represented per pixel.
    const qreal centerLon = viewport->centerLongitude();
    const qreal centerLat = viewport->centerLatitude();
    const qreal rx = ( - viewport->width()  / 2 + x );
    const qreal ry = (   viewport->height() / 2 - y );
    const qreal p = qMax( qSqrt( rx*rx + ry*ry ), qreal(0.0001) ); // ensure we don't divide by zero
    const qreal c = qAtan(2 * p / radius);
    const qreal sinc = qSin(c);
 
    lon = centerLon + qAtan2( rx*sinc , ( p*qCos( centerLat )*qCos( c ) - ry*qSin( centerLat )*sinc  ) );
 
    while ( lon < -M_PI ) lon += 2 * M_PI;
    while ( lon >  M_PI ) lon -= 2 * M_PI;
 
    lat = qAsin( qCos(c)*qSin(centerLat) + ry*sinc*qCos(centerLat)/p );
 
    if ( unit == GeoDataCoordinates::Degree ) {
        lon *= RAD2DEG;
        lat *= RAD2DEG;
    }
 
    return true;
}
 
}