File indexing completed on 2024-04-14 03:48:07

 // SPDX-FileCopyrightText: 2007-2009 David Roberts <dvdr18@gmail.com>
 // 
 // SPDX-License-Identifier: LGPL-2.1-or-later
 
 #include "SunLocator.h"
 
 #include "MarbleGlobal.h"
 #include "MarbleClock.h"
 #include "Planet.h"
 #include "MarbleMath.h"
  
 #include "MarbleDebug.h"
 
 #include <QDateTime>
 
 #include <cmath>
 
 namespace Marble
 {
 
 using std::sin;
 
 class SunLocatorPrivate
 {
 public:
     SunLocatorPrivate( const MarbleClock *clock, const Planet *planet )
         : m_lon( 0.0 ),
           m_lat( 0.0 ),
           m_twilightZone(planet->twilightZone()),
           m_clock( clock ),
           m_planet( planet )
     {
         planet->sunPosition(m_lon, m_lat, clock->dateTime());
     }
 
     qreal m_lon;
     qreal m_lat;
 
     qreal m_twilightZone;
 
     const MarbleClock *const m_clock;
     const Planet *m_planet;
 };
 
 
 SunLocator::SunLocator( const MarbleClock *clock, const Planet *planet )
   : QObject(),
     d( new SunLocatorPrivate( clock, planet ))
 {
 }
 
 SunLocator::~SunLocator()
 {
     delete d;
 }
 
 qreal SunLocator::shading(qreal lon, qreal a, qreal c) const
 {
     // haversine formula
     qreal b = sin((lon-d->m_lon)/2.0);
 //    qreal g = sin((lat-d->m_lat)/2.0);
 //    qreal h = (g*g)+cos(lat)*cos(d->m_lat)*(b*b); 
     qreal h = (a*a) + c * (b*b); 
 
     /*
       h = 0.0 // directly beneath sun
       h = 0.5 // sunrise/sunset line
       h = 1.0 // opposite side of earth to the sun
       theta = 2*asin(sqrt(h))
     */
 
     qreal brightness;
     if ( h <= 0.5 - d->m_twilightZone / 2.0 )
         brightness = 1.0;
     else if ( h >= 0.5 + d->m_twilightZone / 2.0 )
         brightness = 0.0;
     else
         brightness = ( 0.5 + d->m_twilightZone/2.0 - h ) / d->m_twilightZone;
 
     return brightness;
 }
 
 void SunLocator::shadePixel(QRgb &pixcol, qreal brightness)
 {
     // daylight - no change
     if ( brightness > 0.99999 )
         return;
 
     if ( brightness < 0.00001 ) {
         // night
         //      Doing  "pixcol = qRgb(r/2, g/2, b/2);" by shifting some electrons around ;)
         // by shifting some electrons around ;)
         pixcol = qRgb(qRed(pixcol) * 0.35, qGreen(pixcol) * 0.35, qBlue(pixcol)  * 0.35);
         // pixcol = (pixcol & 0xff000000) | ((pixcol >> 1) & 0x7f7f7f);
     } else {
         // gradual shadowing
         int r = qRed( pixcol );
         int g = qGreen( pixcol );
         int b = qBlue( pixcol );
         qreal  d = 0.65 * brightness + 0.35;
         pixcol = qRgb((int)(d * r), (int)(d * g), (int)(d * b));
     }
 }
 
 void SunLocator::shadePixelComposite(QRgb &pixcol, const QRgb &dpixcol,
                                      qreal brightness)
 {
     // daylight - no change
     if ( brightness > 0.99999 )
         return;
 
     if ( brightness < 0.00001 ) {
         // night
         pixcol = dpixcol;
     } else {
         // gradual shadowing
         qreal& d = brightness;
 
         int r = qRed( pixcol );
         int g = qGreen( pixcol );
         int b = qBlue( pixcol );
 
         int dr = qRed( dpixcol );
         int dg = qGreen( dpixcol );
         int db = qBlue( dpixcol );
 
         pixcol = qRgb( (int)( d * r + (1 - d) * dr ),
                        (int)( d * g + (1 - d) * dg ),
                        (int)( d * b + (1 - d) * db ) );
     }
 }
 
 void SunLocator::update()
 {
     d->m_planet->sunPosition(d->m_lon, d->m_lat, d->m_clock->dateTime());
 
     emit positionChanged( getLon(), getLat() );
 }
 
 void SunLocator::setPlanet( const Planet *planet )
 {
     /*
     // This won't work as expected if the same pointer 
     // points to different planets
     if ( planet == d->m_planet ) {
         return;
     }
     */
 
     const Planet *previousPlanet = d->m_planet;
 
     mDebug() << "SunLocator::setPlanet(Planet*)";
     d->m_planet = planet;
     d->m_twilightZone = planet->twilightZone();
     planet->sunPosition(d->m_lon, d->m_lat, d->m_clock->dateTime());
 
     // Initially there might be no planet set.
     // In that case we don't want an update.
     // Update the shading in all other cases.
     if ( !previousPlanet->id().isEmpty() ) {
         emit positionChanged( getLon(), getLat() );
     }
 }
 
 qreal SunLocator::getLon() const
 {
     return d->m_lon * RAD2DEG;
 }
 
 qreal SunLocator::getLat() const
 {
     return d->m_lat * RAD2DEG;
 }
 
 }
 
 #include "moc_SunLocator.cpp"