File indexing completed on 2025-01-05 03:59:33

 // SPDX-License-Identifier: LGPL-2.1-or-later
 //
 // SPDX-FileCopyrightText: 2014 Torsten Rahn <rahn@kde.org>
 //
 
 // Local
 #include "VerticalPerspectiveProjection.h"
 #include "AbstractProjection_p.h"
 
 #include <QIcon>
 #include <qmath.h>
 
 #include <klocalizedstring.h>
 
 // Marble
 #include "ViewportParams.h"
 #include "GeoDataPoint.h"
 #include "GeoDataLineString.h"
 #include "GeoDataCoordinates.h"
 #include "MarbleGlobal.h"
 #include "AzimuthalProjection_p.h"
 
 #include "digikam_debug.h"
 
 #define SAFE_DISTANCE
 
 namespace Marble
 {
 
 class VerticalPerspectiveProjectionPrivate : public AzimuthalProjectionPrivate
 {
   public:
     explicit VerticalPerspectiveProjectionPrivate( VerticalPerspectiveProjection * parent );
 
     void calculateConstants(qreal radius) const;
 
     mutable qreal m_P; ///< Distance of the point of perspective in earth diameters
     mutable qreal m_previousRadius;
     mutable qreal m_altitudeToPixel;
     mutable qreal m_perspectiveRadius;
     mutable qreal m_pPfactor;
 
     Q_DECLARE_PUBLIC( VerticalPerspectiveProjection )
 };
 
 VerticalPerspectiveProjection::VerticalPerspectiveProjection()
     : AzimuthalProjection( new VerticalPerspectiveProjectionPrivate( this ) )
 {
     setMinLat( minValidLat() );
     setMaxLat( maxValidLat() );
 }
 
 VerticalPerspectiveProjection::VerticalPerspectiveProjection( VerticalPerspectiveProjectionPrivate *dd )
         : AzimuthalProjection( dd )
 {
     setMinLat( minValidLat() );
     setMaxLat( maxValidLat() );
 }
 
 VerticalPerspectiveProjection::~VerticalPerspectiveProjection()
 {
 }
 
 
 VerticalPerspectiveProjectionPrivate::VerticalPerspectiveProjectionPrivate( VerticalPerspectiveProjection * parent )
         : AzimuthalProjectionPrivate( parent ),
           m_P(1),
           m_previousRadius(1),
           m_altitudeToPixel(1),
           m_perspectiveRadius(1),
           m_pPfactor(1)
 {
 }
 
 
 QString VerticalPerspectiveProjection::name() const
 {
     return i18n( "Vertical Perspective Projection" );
 }
 
 QString VerticalPerspectiveProjection::description() const
 {
     return i18n( "<p><b>Vertical Perspective Projection</b> (\"orthogonal\")</p><p> Shows the earth as it appears from a relatively short distance above the surface. Applications: Used for Virtual Globes.</p>" );
 }
 
 QIcon VerticalPerspectiveProjection::icon() const
 {
     return QIcon::fromTheme(QStringLiteral("map-globe"));
 }
 
 void VerticalPerspectiveProjectionPrivate::calculateConstants(qreal radius) const
 {
     if (radius == m_previousRadius)  return;
     m_previousRadius = radius;
     m_P = 1.5 + 3 * 1000 * 0.4 / radius / qTan(0.5 * 110 * DEG2RAD);
     m_altitudeToPixel = radius / (EARTH_RADIUS * qSqrt((m_P-1)/(m_P+1)));
     m_perspectiveRadius = radius / qSqrt((m_P-1)/(m_P+1));
     m_pPfactor = (m_P+1)/(m_perspectiveRadius*m_perspectiveRadius*(m_P-1));
 }
 
 qreal VerticalPerspectiveProjection::clippingRadius() const
 {
     return 1;
 }
 
 bool VerticalPerspectiveProjection::screenCoordinates( const GeoDataCoordinates &coordinates,
                                              const ViewportParams *viewport,
                                              qreal &x, qreal &y, bool &globeHidesPoint ) const
 {
     Q_D(const VerticalPerspectiveProjection);
     d->calculateConstants(viewport->radius());
     const qreal P =  d->m_P;
     const qreal deltaLambda = coordinates.longitude() - viewport->centerLongitude();
     const qreal phi = coordinates.latitude();
     const qreal phi1 = viewport->centerLatitude();
 
     qreal cosC = qSin( phi1 ) * qSin( phi ) + qCos( phi1 ) * qCos( phi ) * qCos( deltaLambda );
 
     // Don't display placemarks that are below 10km altitude and
     // are on the Earth's backside (where cosC < 1/P)
     if (cosC < 1/P && coordinates.altitude() < 10000) {
         globeHidesPoint = true;
         return false;
     }
 
     // Let (x, y) be the position on the screen of the placemark ..
     // First determine the position in unit coordinates:
     qreal k = (P - 1) / (P - cosC); // scale factor
     x = ( qCos( phi ) * qSin( deltaLambda ) ) * k;
     y = ( qCos( phi1 ) * qSin( phi ) - qSin( phi1 ) * qCos( phi ) * qCos( deltaLambda ) ) * k;
 
     // Transform to screen coordinates
     qreal pixelAltitude = (coordinates.altitude() + EARTH_RADIUS) * d->m_altitudeToPixel;
     x *= pixelAltitude;
     y *= pixelAltitude;
 
 
     // Don't display satellites that are on the Earth's backside:
     if (cosC < 1/P && x*x+y*y < viewport->radius() * viewport->radius()) {
         globeHidesPoint = true;
         return false;
     }
     // The remaining placemarks are definitely not on the Earth's backside
     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 VerticalPerspectiveProjection::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 VerticalPerspectiveProjection::geoCoordinates( const int x, const int y,
                                           const ViewportParams *viewport,
                                           qreal& lon, qreal& lat,
                                           GeoDataCoordinates::Unit unit ) const
 {
     Q_D(const VerticalPerspectiveProjection);
     d->calculateConstants(viewport->radius());
     const qreal P = d->m_P;
     const qreal rx = ( - viewport->width()  / 2 + x );
     const qreal ry = (   viewport->height() / 2 - y );
     const qreal p2 = rx*rx + ry*ry;
 
     if (p2 == 0) {
         lon = viewport->centerLongitude();
         lat = viewport->centerLatitude();
         return true;
     }
 
     const qreal pP = p2*d->m_pPfactor;
 
     if ( pP > 1) return false;
 
     const qreal p = qSqrt(p2);
     const qreal fract = d->m_perspectiveRadius*(P-1)/p;
     const qreal c = qAsin((P-qSqrt(1-pP))/(fract+1/fract));
     const qreal sinc = qSin(c);
 
     const qreal centerLon = viewport->centerLongitude();
     const qreal centerLat = viewport->centerLatitude();
     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;
 }
 
 }