File indexing completed on 2025-01-05 03:59:32

 // SPDX-License-Identifier: LGPL-2.1-or-later
 //
 // SPDX-FileCopyrightText: 2014 Gábor Péterffy <peterffy95@gmail.org>
 //
 
 // Local
 #include "AzimuthalProjection.h"
 #include "AzimuthalProjection_p.h"
 #include "AbstractProjection_p.h"
 
 // Marble
 #include "GeoDataLinearRing.h"
 #include "GeoDataLineString.h"
 #include "GeoDataCoordinates.h"
 #include "GeoDataLatLonAltBox.h"
 #include "ViewportParams.h"
 
 #include <QPainterPath>
 
 
 namespace Marble {
 
 bool AzimuthalProjection::isClippedToSphere() const
 {
     return true;
 }
 
 qreal AzimuthalProjection::clippingRadius() const
 {
     return 1;
 }
 
 bool AzimuthalProjection::screenCoordinates( const GeoDataLineString &lineString,
                                                   const ViewportParams *viewport,
                                                   QVector<QPolygonF *> &polygons ) const
 {
 
     Q_D( const AzimuthalProjection );
     // Compare bounding box size of the line string with the angularResolution
     // Immediately return if the latLonAltBox is smaller.
     if ( !viewport->resolves( lineString.latLonAltBox() ) ) {
 //      qCDebug(DIGIKAM_MARBLE_LOG) << "Object too small to be resolved";
         return false;
     }
 
     d->lineStringToPolygon( lineString, viewport, polygons );
     return true;
 }
 
 bool AzimuthalProjection::mapCoversViewport( const ViewportParams *viewport ) const
 {
         qint64  radius = viewport->radius() * viewport->currentProjection()->clippingRadius();
         qint64  width  = viewport->width();
         qint64  height = viewport->height();
 
         // This first test is a quick one that will catch all really big
         // radii and prevent overflow in the real test.
         if ( radius > width + height )
             return true;
 
         // This is the real test.  The 4 is because we are really
         // comparing to width/2 and height/2.
         if ( 4 * radius * radius >= width * width + height * height )
             return true;
 
         return false;
 }
 
 GeoDataLatLonAltBox AzimuthalProjection::latLonAltBox( const QRect& screenRect,
                                                        const ViewportParams *viewport ) const
 {
     // For the case where the whole viewport gets covered there is a
     // pretty dirty and generic detection algorithm:
     GeoDataLatLonAltBox latLonAltBox = AbstractProjection::latLonAltBox( screenRect, viewport );
 
     // If the whole globe is visible we can easily calculate
     // analytically the lon-/lat- range.
     qreal pitch = GeoDataCoordinates::normalizeLat( viewport->planetAxis().pitch() );
 
     if ( 2.0 * viewport->radius() <= viewport->height()
          &&  2.0 * viewport->radius() <= viewport->width() )
     {
         // Unless the planetaxis is in the screen plane the allowed longitude range
         // covers full -180 deg to +180 deg:
         if ( pitch > 0.0 && pitch < +M_PI ) {
             latLonAltBox.setWest(  -M_PI );
             latLonAltBox.setEast(  +M_PI );
             latLonAltBox.setNorth( +fabs( M_PI / 2.0 - fabs( pitch ) ) );
             latLonAltBox.setSouth( -M_PI / 2.0 );
         }
         if ( pitch < 0.0 && pitch > -M_PI ) {
             latLonAltBox.setWest(  -M_PI );
             latLonAltBox.setEast(  +M_PI );
             latLonAltBox.setNorth( +M_PI / 2.0 );
             latLonAltBox.setSouth( -fabs( M_PI / 2.0 - fabs( pitch ) ) );
         }
 
         // Last but not least we deal with the rare case where the
         // globe is fully visible and pitch = 0.0 or pitch = -M_PI or
         // pitch = +M_PI
         if ( pitch == 0.0 || pitch == -M_PI || pitch == +M_PI ) {
             qreal yaw = viewport->planetAxis().yaw();
             latLonAltBox.setWest( GeoDataCoordinates::normalizeLon( yaw - M_PI / 2.0 ) );
             latLonAltBox.setEast( GeoDataCoordinates::normalizeLon( yaw + M_PI / 2.0 ) );
             latLonAltBox.setNorth( +M_PI / 2.0 );
             latLonAltBox.setSouth( -M_PI / 2.0 );
         }
 
         return latLonAltBox;
     }
 
     // Now we check whether maxLat (e.g. the north pole) gets displayed
     // inside the viewport to get more accurate values for east and west.
 
     // We need a point on the screen at maxLat that definitely gets displayed:
     qreal averageLongitude = ( latLonAltBox.west() + latLonAltBox.east() ) / 2.0;
 
     GeoDataCoordinates maxLatPoint( averageLongitude, maxLat(), 0.0, GeoDataCoordinates::Radian );
     GeoDataCoordinates minLatPoint( averageLongitude, minLat(), 0.0, GeoDataCoordinates::Radian );
 
     qreal dummyX, dummyY; // not needed
     bool dummyVal;
 
     if ( screenCoordinates( maxLatPoint, viewport, dummyX, dummyY, dummyVal ) ||
          screenCoordinates( minLatPoint, viewport, dummyX, dummyY, dummyVal ) ) {
         latLonAltBox.setWest( -M_PI );
         latLonAltBox.setEast( +M_PI );
     }
 
     return latLonAltBox;
 }
 
 QPainterPath AzimuthalProjection::mapShape( const ViewportParams *viewport ) const
 {
     int  radius    = viewport->radius() * viewport->currentProjection()->clippingRadius();
     int  imgWidth  = viewport->width();
     int  imgHeight = viewport->height();
 
     QPainterPath fullRect;
     fullRect.addRect(  0 , 0 , imgWidth, imgHeight );
 
     // If the globe covers the whole image, then the projected region represents
     // all of the image.
     // Otherwise the active region has got the shape of the visible globe.
 
     if ( !viewport->mapCoversViewport() ) {
         QPainterPath mapShape;
         mapShape.addEllipse(
             imgWidth  / 2 - radius,
             imgHeight / 2 - radius,
             2 * radius,
             2 * radius );
         return mapShape.intersected( fullRect );
     }
 
     return fullRect;
 }
 
 AzimuthalProjection::AzimuthalProjection(AzimuthalProjectionPrivate * dd) :
     AbstractProjection( dd )
 {
 }
 
 AzimuthalProjection::~AzimuthalProjection()
 {
 }
 
 void AzimuthalProjectionPrivate::tessellateLineSegment( const GeoDataCoordinates &aCoords,
                                                 qreal ax, qreal ay,
                                                 const GeoDataCoordinates &bCoords,
                                                 qreal bx, qreal by,
                                                 QVector<QPolygonF*> &polygons,
                                                 const ViewportParams *viewport,
                                                 TessellationFlags f,
                                                 bool allowLatePolygonCut ) const
 {
     // We take the manhattan length as a distance approximation
     // that can be too big by a factor of sqrt(2)
     qreal distance = fabs((bx - ax)) + fabs((by - ay));
 #ifdef SAFE_DISTANCE
     // Interpolate additional nodes if the line segment that connects the
     // current or previous nodes might cross the viewport.
     // The latter can pretty safely be excluded for most projections if both points
     // are located on the same side relative to the viewport boundaries and if they are
     // located more than half the line segment distance away from the viewport.
     const qreal safeDistance = - 0.5 * distance;
     if (   !( bx < safeDistance && ax < safeDistance )
         || !( by < safeDistance && ay < safeDistance )
         || !( bx + safeDistance > viewport->width()
             && ax + safeDistance > viewport->width() )
         || !( by + safeDistance > viewport->height()
             && ay + safeDistance > viewport->height() )
     )
     {
 #endif
         int maxTessellationFactor = viewport->radius() < 20000 ? 10 : 20;
         int const finalTessellationPrecision = qBound(2, viewport->radius()/200, maxTessellationFactor) * tessellationPrecision;
 
         // Let the line segment follow the spherical surface
         // if the distance between the previous point and the current point
         // on screen is too big
 
         if ( distance > finalTessellationPrecision ) {
             const int tessellatedNodes = qMin<int>( distance / finalTessellationPrecision, maxTessellationNodes );
 
             processTessellation( aCoords, bCoords,
                                  tessellatedNodes,
                                  polygons,
                                  viewport,
                                  f,
                                  allowLatePolygonCut);
         }
         else {
             crossHorizon( bCoords, polygons, viewport, allowLatePolygonCut );
         }
 #ifdef SAFE_DISTANCE
     }
 #endif
 }
 
 
 void AzimuthalProjectionPrivate::processTessellation( const GeoDataCoordinates &previousCoords,
                                                     const GeoDataCoordinates &currentCoords,
                                                     int tessellatedNodes,
                                                     QVector<QPolygonF*> &polygons,
                                                     const ViewportParams *viewport,
                                                     TessellationFlags f,
                                                     bool allowLatePolygonCut ) const
 {
 
     const bool clampToGround = f.testFlag( FollowGround );
     const bool followLatitudeCircle = f.testFlag( RespectLatitudeCircle )
                                       && previousCoords.latitude() == currentCoords.latitude();
 
     // Calculate steps for tessellation: lonDiff and altDiff
     qreal lonDiff = 0.0;
     if ( followLatitudeCircle ) {
         const int previousSign = previousCoords.longitude() > 0 ? 1 : -1;
         const int currentSign = currentCoords.longitude() > 0 ? 1 : -1;
 
         lonDiff = currentCoords.longitude() - previousCoords.longitude();
         if ( previousSign != currentSign
              && fabs(previousCoords.longitude()) + fabs(currentCoords.longitude()) > M_PI ) {
             if ( previousSign > currentSign ) {
                 // going eastwards ->
                 lonDiff += 2 * M_PI ;
             } else {
                 // going westwards ->
                 lonDiff -= 2 * M_PI;
             }
         }
     }
 
     // Create the tessellation nodes.
     GeoDataCoordinates previousTessellatedCoords = previousCoords;
     for ( int i = 1; i <= tessellatedNodes; ++i ) {
         const qreal t = (qreal)(i) / (qreal)( tessellatedNodes + 1 );
 
         GeoDataCoordinates currentTessellatedCoords;
 
         if ( followLatitudeCircle ) {
             // To tessellate along latitude circles use the
             // linear interpolation of the longitude.
             const qreal altDiff = currentCoords.altitude() - previousCoords.altitude();
             const qreal altitude = altDiff * t + previousCoords.altitude();
             const qreal lon = lonDiff * t + previousCoords.longitude();
             const qreal lat = previousTessellatedCoords.latitude();
 
             currentTessellatedCoords = GeoDataCoordinates(lon, lat, altitude);
         }
         else {
             // To tessellate along great circles use the
             // normalized linear interpolation ("NLERP") for latitude and longitude.
             currentTessellatedCoords = previousCoords.nlerp(currentCoords, t);
         }
 
         if (clampToGround) {
             currentTessellatedCoords.setAltitude(0);
         }
 
         crossHorizon( currentTessellatedCoords, polygons, viewport, allowLatePolygonCut );
         previousTessellatedCoords = currentTessellatedCoords;
     }
 
     // For the clampToGround case add the "current" coordinate after adding all other nodes.
     GeoDataCoordinates currentModifiedCoords( currentCoords );
     if ( clampToGround ) {
         currentModifiedCoords.setAltitude( 0.0 );
     }
     crossHorizon( currentModifiedCoords, polygons, viewport, allowLatePolygonCut );
 }
 
 void AzimuthalProjectionPrivate::crossHorizon( const GeoDataCoordinates & bCoord,
                                               QVector<QPolygonF*> &polygons,
                                               const ViewportParams *viewport,
                                               bool allowLatePolygonCut
                                              ) const
 {
     qreal x, y;
     bool globeHidesPoint;
 
     Q_Q( const AbstractProjection );
 
     q->screenCoordinates( bCoord, viewport, x, y, globeHidesPoint );
 
     if( !globeHidesPoint ) {
         *polygons.last() << QPointF( x, y );
     }
     else {
         if ( allowLatePolygonCut && !polygons.last()->isEmpty() ) {
             QPolygonF *path = new QPolygonF;
             polygons.append( path );
         }
     }
 }
 
 bool AzimuthalProjectionPrivate::lineStringToPolygon( const GeoDataLineString &lineString,
                                               const ViewportParams *viewport,
                                               QVector<QPolygonF *> &polygons ) const
 {
     Q_Q( const AzimuthalProjection );
 
     const TessellationFlags f = lineString.tessellationFlags();
     bool const tessellate = lineString.tessellate();
     const bool noFilter = f.testFlag(PreventNodeFiltering);
 
 
     qreal x = 0;
     qreal y = 0;
     bool globeHidesPoint = false;
 
     qreal previousX = -1.0;
     qreal previousY = -1.0;
     bool previousGlobeHidesPoint = false;
 
     qreal horizonX = -1.0;
     qreal horizonY = -1.0;
 
     QPolygonF * polygon = new QPolygonF;
     if (!tessellate) {
         polygon->reserve(lineString.size());
     }
     polygons.append( polygon );
 
     GeoDataLineString::ConstIterator itCoords = lineString.constBegin();
     GeoDataLineString::ConstIterator itPreviousCoords = lineString.constBegin();
 
     // Some projections display the earth in a way so that there is a
     // foreside and a backside.
     // The horizon is the line (usually a circle) which separates both
     // sides from each other and resembles the map shape.
     GeoDataCoordinates horizonCoords;
 
     // A horizon pair is a pair of two subsequent horizon crossings:
     // The first one describes the point where a line string disappears behind the horizon.
     // and where horizonPair is set to true.
     // The second one describes the point where the line string reappears.
     // In this case the two points are connected and horizonPair is set to false again.
     bool horizonPair = false;
     GeoDataCoordinates horizonDisappearCoords;
 
     // If the first horizon crossing in a line string describes the appearance of
     // a line string then we call it a "horizon orphan" and horizonOrphan is set to true.
     // In this case once the last horizon crossing in the line string is reached
     // it needs to be connected to the orphan.
     bool horizonOrphan = false;
     GeoDataCoordinates horizonOrphanCoords;
 
     GeoDataLineString::ConstIterator itBegin = lineString.constBegin();
     GeoDataLineString::ConstIterator itEnd = lineString.constEnd();
 
     bool processingLastNode = false;
 
     // We use a while loop to be able to cover linestrings as well as linear rings:
     // Linear rings require to tessellate the path from the last node to the first node
     // which isn't really convenient to achieve with a for loop ...
 
     const bool isLong = lineString.size() > 10;
     const int maximumDetail = levelForResolution(viewport->angularResolution());
     // The first node of optimized linestrings has a non-zero detail value.
     const bool hasDetail = itBegin->detail() != 0;
 
     while ( itCoords != itEnd )
     {
         // Optimization for line strings with a big amount of nodes
         bool skipNode = (hasDetail ? itCoords->detail() > maximumDetail
                 : itCoords != itBegin && isLong && !processingLastNode &&
                 !viewport->resolves( *itPreviousCoords, *itCoords ) );
 
         if ( !skipNode || noFilter) {
 
             q->screenCoordinates( *itCoords, viewport, x, y, globeHidesPoint );
 
             // Initializing variables that store the values of the previous iteration
             if ( !processingLastNode && itCoords == itBegin ) {
                 previousGlobeHidesPoint = globeHidesPoint;
                 itPreviousCoords = itCoords;
                 previousX = x;
                 previousY = y;
             }
 
             // Check for the "horizon case" (which is present e.g. for the spherical projection
             const bool isAtHorizon = ( globeHidesPoint || previousGlobeHidesPoint ) &&
                                      ( globeHidesPoint !=  previousGlobeHidesPoint );
 
             if ( isAtHorizon ) {
                 // Handle the "horizon case"
                 horizonCoords = findHorizon( *itPreviousCoords, *itCoords, viewport, f );
 
                 if ( lineString.isClosed() ) {
                     if ( horizonPair ) {
                         horizonToPolygon( viewport, horizonDisappearCoords, horizonCoords, polygons.last() );
                         horizonPair = false;
                     }
                     else {
                         if ( globeHidesPoint ) {
                             horizonDisappearCoords = horizonCoords;
                             horizonPair = true;
                         }
                         else {
                             horizonOrphanCoords = horizonCoords;
                             horizonOrphan = true;
                         }
                     }
                 }
 
                 q->screenCoordinates( horizonCoords, viewport, horizonX, horizonY );
 
                 // If the line appears on the visible half we need
                 // to add an interpolated point at the horizon as the previous point.
                 if ( previousGlobeHidesPoint ) {
                     *polygons.last() << QPointF( horizonX, horizonY );
                 }
             }
 
             // This if-clause contains the section that tessellates the line
             // segments of a linestring. If you are about to learn how the code of
             // this class works you can safely ignore this section for a start.
 
             if ( lineString.tessellate() /* && ( isVisible || previousIsVisible ) */ ) {
 
                 if ( !isAtHorizon ) {
 
                     tessellateLineSegment( *itPreviousCoords, previousX, previousY,
                                            *itCoords, x, y,
                                            polygons, viewport,
                                            f, !lineString.isClosed() );
 
                 }
                 else {
                     // Connect the interpolated  point at the horizon with the
                     // current or previous point in the line.
                     if ( previousGlobeHidesPoint ) {
                         tessellateLineSegment( horizonCoords, horizonX, horizonY,
                                                *itCoords, x, y,
                                                polygons, viewport,
                                                f, !lineString.isClosed() );
                     }
                     else {
                         tessellateLineSegment( *itPreviousCoords, previousX, previousY,
                                                horizonCoords, horizonX, horizonY,
                                                polygons, viewport,
                                                f, !lineString.isClosed() );
                     }
                 }
             }
             else {
                 if ( !globeHidesPoint ) {
                     *polygons.last() << QPointF( x, y );
                 }
                 else {
                     if ( !previousGlobeHidesPoint && isAtHorizon ) {
                         *polygons.last() << QPointF( horizonX, horizonY );
                     }
                 }
             }
 
             if ( globeHidesPoint ) {
                 if (   !previousGlobeHidesPoint
                     && !lineString.isClosed()
                     ) {
                     polygons.append( new QPolygonF );
                 }
             }
 
             previousGlobeHidesPoint = globeHidesPoint;
             itPreviousCoords = itCoords;
             previousX = x;
             previousY = y;
         }
 
         // Here we modify the condition to be able to process the
         // first node after the last node in a LinearRing.
 
         if ( processingLastNode ) {
             break;
         }
         ++itCoords;
 
         if ( itCoords == itEnd  && lineString.isClosed() ) {
             itCoords = itBegin;
             processingLastNode = true;
         }
     }
 
     // In case of horizon crossings, make sure that we always get a
     // polygon closed correctly.
     if ( horizonOrphan && lineString.isClosed() ) {
         horizonToPolygon( viewport, horizonCoords, horizonOrphanCoords, polygons.last() );
     }
 
     if ( polygons.last()->size() <= 1 ){
         delete polygons.last();
         polygons.pop_back(); // Clean up "unused" empty polygon instances
     }
 
     return polygons.isEmpty();
 }
 
 void AzimuthalProjectionPrivate::horizonToPolygon( const ViewportParams *viewport,
                                            const GeoDataCoordinates & disappearCoords,
                                            const GeoDataCoordinates & reappearCoords,
                                            QPolygonF * polygon ) const
 {
     qreal x, y;
 
     const qreal imageHalfWidth  = viewport->width() / 2;
     const qreal imageHalfHeight = viewport->height() / 2;
 
     bool dummyGlobeHidesPoint = false;
 
     Q_Q( const AzimuthalProjection );
     // Calculate the angle of the position vectors of both coordinates
     q->screenCoordinates( disappearCoords, viewport, x, y, dummyGlobeHidesPoint );
     qreal alpha = atan2( y - imageHalfHeight,
                          x - imageHalfWidth );
 
     q->screenCoordinates( reappearCoords, viewport, x, y, dummyGlobeHidesPoint );
     qreal beta =  atan2( y - imageHalfHeight,
                          x - imageHalfWidth );
 
     // Calculate the difference between both
     qreal diff = GeoDataCoordinates::normalizeLon( beta - alpha );
 
     qreal sgndiff = diff < 0 ? -1 : 1;
 
     const qreal arcradius = q->clippingRadius() * viewport->radius();
     const int itEnd = fabs(diff * RAD2DEG);
 
     // Create a polygon that resembles an arc between the two position vectors
     polygon->reserve(polygon->size() + itEnd);
     for ( int it = 1; it <= itEnd; ++it ) {
         const qreal angle = alpha + DEG2RAD * sgndiff * it;
         const qreal itx = imageHalfWidth  +  arcradius * cos( angle );
         const qreal ity = imageHalfHeight +  arcradius * sin( angle );
         *polygon << QPointF( itx, ity );
     }
 }
 
 
 GeoDataCoordinates AzimuthalProjectionPrivate::findHorizon( const GeoDataCoordinates & previousCoords,
                                                     const GeoDataCoordinates & currentCoords,
                                                     const ViewportParams *viewport,
                                                     TessellationFlags f) const
 {
     bool currentHide = globeHidesPoint( currentCoords, viewport ) ;
 
     return doFindHorizon(previousCoords, currentCoords, viewport, f, currentHide, 0);
 }
 
 
 GeoDataCoordinates AzimuthalProjectionPrivate::doFindHorizon( const GeoDataCoordinates & previousCoords,
                                                     const GeoDataCoordinates & currentCoords,
                                                     const ViewportParams *viewport,
                                                     TessellationFlags f,
                                                     bool currentHide,
                                                     int recursionCounter ) const
 {
     if ( recursionCounter > 20 ) {
         return currentHide ? previousCoords : currentCoords;
     }
     ++recursionCounter;
 
     bool followLatitudeCircle = false;
 
     // Calculate steps for tessellation: lonDiff and altDiff
     qreal lonDiff = 0.0;
     qreal previousLongitude = 0.0;
     qreal previousLatitude = 0.0;
 
     if ( f.testFlag( RespectLatitudeCircle ) ) {
         previousCoords.geoCoordinates( previousLongitude, previousLatitude );
         qreal previousSign = previousLongitude > 0 ? 1 : -1;
 
         qreal currentLongitude = 0.0;
         qreal currentLatitude = 0.0;
         currentCoords.geoCoordinates( currentLongitude, currentLatitude );
         qreal currentSign = currentLongitude > 0 ? 1 : -1;
 
         if ( previousLatitude == currentLatitude ) {
             followLatitudeCircle = true;
 
             lonDiff = currentLongitude - previousLongitude;
             if ( previousSign != currentSign
                  && fabs(previousLongitude) + fabs(currentLongitude) > M_PI ) {
                 if ( previousSign > currentSign ) {
                     // going eastwards ->
                     lonDiff += 2 * M_PI ;
                 } else {
                     // going westwards ->
                     lonDiff -= 2 * M_PI;
                 }
             }
 
         }
         else {
 //            qCDebug(DIGIKAM_MARBLE_LOG) << "Don't FollowLatitudeCircle";
         }
     }
 
     GeoDataCoordinates horizonCoords;
 
     if ( followLatitudeCircle ) {
         // To tessellate along latitude circles use the
         // linear interpolation of the longitude.
         const qreal altDiff = currentCoords.altitude() - previousCoords.altitude();
         const qreal altitude = previousCoords.altitude() + 0.5 * altDiff;
         const qreal lon = lonDiff * 0.5 + previousLongitude;
         const qreal lat = previousLatitude;
 
         horizonCoords = GeoDataCoordinates(lon, lat, altitude);
     }
     else {
         // To tessellate along great circles use the
         // normalized linear interpolation ("NLERP") for latitude and longitude.
         horizonCoords = previousCoords.nlerp(currentCoords, 0.5);
     }
 
     bool horizonHide = globeHidesPoint( horizonCoords, viewport );
 
     if ( horizonHide != currentHide ) {
         return doFindHorizon(horizonCoords, currentCoords, viewport, f, currentHide, recursionCounter);
     }
 
     return doFindHorizon(previousCoords, horizonCoords, viewport, f, horizonHide, recursionCounter);
 }
 
 
 bool AzimuthalProjectionPrivate::globeHidesPoint( const GeoDataCoordinates &coordinates,
                                           const ViewportParams *viewport ) const
 {
     bool globeHidesPoint;
     qreal dummyX, dummyY;
 
     Q_Q( const AzimuthalProjection );
     q->screenCoordinates(coordinates, viewport, dummyX, dummyY, globeHidesPoint);
     return globeHidesPoint;
 }
 
 
 }