File indexing completed on 2024-05-05 03:49:52

 // SPDX-License-Identifier: LGPL-2.1-or-later
 //
 // SPDX-FileCopyrightText: 2007 Inge Wallin <ingwa@kde.org>
 // SPDX-FileCopyrightText: 2007-2012 Torsten Rahn <rahn@kde.org>
 // SPDX-FileCopyrightText: 2012 Cezar Mocan <mocancezar@gmail.com>
 //
 
 // Local
 #include "CylindricalProjection.h"
 
 #include "CylindricalProjection_p.h"
 
 // Marble
 #include "GeoDataLinearRing.h"
 #include "GeoDataLineString.h"
 #include "GeoDataCoordinates.h"
 #include "GeoDataLatLonAltBox.h"
 #include "ViewportParams.h"
 
 #include <QPainterPath>
 
 // Maximum amount of nodes that are created automatically between actual nodes.
 static const int maxTessellationNodes = 200;
 
 namespace Marble {
 
 CylindricalProjection::CylindricalProjection()
         : AbstractProjection( new CylindricalProjectionPrivate( this ) )
 {
 }
 
 CylindricalProjection::CylindricalProjection( CylindricalProjectionPrivate* dd )
         : AbstractProjection( dd )
 {
 }
 
 CylindricalProjection::~CylindricalProjection()
 {
 }
 
 CylindricalProjectionPrivate::CylindricalProjectionPrivate( CylindricalProjection * parent )
         : AbstractProjectionPrivate( parent ),
           q_ptr( parent )
 {
 
 }
 
 
 QPainterPath CylindricalProjection::mapShape( const ViewportParams *viewport ) const
 {
     // Convenience variables
     int  width  = viewport->width();
     int  height = viewport->height();
 
     qreal  yTop;
     qreal  yBottom;
     qreal  xDummy;
 
     // Get the top and bottom coordinates of the projected map.
     screenCoordinates( 0.0, maxLat(), viewport, xDummy, yTop );
     screenCoordinates( 0.0, minLat(), viewport, xDummy, yBottom );
 
     // Don't let the map area be outside the image
     if ( yTop < 0 )
         yTop = 0;
     if ( yBottom > height )
         yBottom =  height;
 
     QPainterPath mapShape;
     mapShape.addRect(
                     0,
                     yTop,
                     width,
                     yBottom - yTop );
 
     return mapShape;
 }
 
 bool CylindricalProjection::screenCoordinates( const GeoDataLineString &lineString,
                                                   const ViewportParams *viewport,
                                                   QVector<QPolygonF *> &polygons ) const
 {
 
     Q_D( const CylindricalProjection );
     // Compare bounding box size of the line string with the angularResolution
     // Immediately return if the latLonAltBox is smaller.
     if ( !viewport->resolves( lineString.latLonAltBox() ) ) {
     //    mDebug() << "Object too small to be resolved";
         return false;
     }
 
     QVector<QPolygonF *> subPolygons;
     d->lineStringToPolygon( lineString, viewport, subPolygons );
 
     polygons << subPolygons;
     return polygons.isEmpty();
 }
 int CylindricalProjectionPrivate::tessellateLineSegment( const GeoDataCoordinates &aCoords,
                                                 qreal ax, qreal ay,
                                                 const GeoDataCoordinates &bCoords,
                                                 qreal bx, qreal by,
                                                 QVector<QPolygonF*> &polygons,
                                                 const ViewportParams *viewport,
                                                 TessellationFlags f,
                                                 int mirrorCount,
                                                 qreal repeatDistance) 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 );
 
             mirrorCount = processTessellation( aCoords, bCoords,
                                  tessellatedNodes,
                                  polygons,
                                  viewport,
                                  f,
                                  mirrorCount,
                                  repeatDistance );
         }
         else {
             mirrorCount = crossDateLine( aCoords, bCoords, bx, by, polygons, mirrorCount, repeatDistance );
         }
 #ifdef SAFE_DISTANCE
     }
 #endif
     return mirrorCount;
 }
 
 
 int CylindricalProjectionPrivate::processTessellation( const GeoDataCoordinates &previousCoords,
                                                     const GeoDataCoordinates &currentCoords,
                                                     int tessellatedNodes,
                                                     QVector<QPolygonF*> &polygons,
                                                     const ViewportParams *viewport,
                                                     TessellationFlags f,
                                                     int mirrorCount,
                                                     qreal repeatDistance) 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;
             }
         }
         if ( fabs( lonDiff ) == 2 * M_PI ) {
             return mirrorCount;
         }
     }
 
     // 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.
             // interpolate the altitude, too
             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);
         }
 
         Q_Q(const CylindricalProjection);
         qreal bx, by;
         q->screenCoordinates( currentTessellatedCoords, viewport, bx, by );
         mirrorCount = crossDateLine( previousTessellatedCoords, currentTessellatedCoords, bx, by, polygons,
                                      mirrorCount, repeatDistance );
         previousTessellatedCoords = currentTessellatedCoords;
     }
 
     // For the clampToGround case add the "current" coordinate after adding all other nodes.
     GeoDataCoordinates currentModifiedCoords( currentCoords );
     if ( clampToGround ) {
         currentModifiedCoords.setAltitude( 0.0 );
     }
     Q_Q(const CylindricalProjection);
     qreal bx, by;
     q->screenCoordinates( currentModifiedCoords, viewport, bx, by );
     mirrorCount = crossDateLine( previousTessellatedCoords, currentModifiedCoords, bx, by, polygons,
                                  mirrorCount, repeatDistance );
     return mirrorCount;
 }
 
 int CylindricalProjectionPrivate::crossDateLine( const GeoDataCoordinates & aCoord,
                                                  const GeoDataCoordinates & bCoord,
                                                  qreal bx,
                                                  qreal by,
                                                  QVector<QPolygonF*> &polygons,
                                                  int mirrorCount,
                                                  qreal repeatDistance )
 {
     qreal aLon = aCoord.longitude();
     qreal aSign = aLon > 0 ? 1 : -1;
 
     qreal bLon = bCoord.longitude();
     qreal bSign = bLon > 0 ? 1 : -1;
 
     qreal delta = 0;
     if( aSign != bSign && fabs(aLon) + fabs(bLon) > M_PI ) {
         int sign = aSign > bSign ? 1 : -1;
         mirrorCount += sign;
     }
     delta = repeatDistance * mirrorCount;
     *polygons.last() << QPointF( bx + delta, by );
 
     return mirrorCount;
 }
 
 bool CylindricalProjectionPrivate::lineStringToPolygon( const GeoDataLineString &lineString,
                                               const ViewportParams *viewport,
                                               QVector<QPolygonF *> &polygons ) const
 {
     const TessellationFlags f = lineString.tessellationFlags();
     bool const tessellate = lineString.tessellate();
     const bool noFilter = f.testFlag(PreventNodeFiltering);
 
     qreal x = 0;
     qreal y = 0;
 
     qreal previousX = -1.0;
     qreal previousY = -1.0;
 
     int mirrorCount = 0;
     qreal distance = repeatDistance( viewport );
 
     QPolygonF * polygon = new QPolygonF;
     if (!tessellate) {
         polygon->reserve(lineString.size());
     }
     polygons.append( polygon );
 
     GeoDataLineString::ConstIterator itCoords = lineString.constBegin();
     GeoDataLineString::ConstIterator itPreviousCoords = lineString.constBegin();
 
     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;
 
     bool isStraight = lineString.latLonAltBox().height() == 0 || lineString.latLonAltBox().width() == 0;
 
     Q_Q( const CylindricalProjection );
     bool const isClosed = lineString.isClosed();
     while ( itCoords != itEnd )
     {
         // Optimization for line strings with a big amount of nodes
         bool skipNode = (hasDetail ? itCoords->detail() > maximumDetail
                 : isLong && !processingLastNode && itCoords != itBegin &&
                 !viewport->resolves( *itPreviousCoords, *itCoords ) );
 
         if ( !skipNode || noFilter) {
             q->screenCoordinates( *itCoords, viewport, x, y );
 
             // Initializing variables that store the values of the previous iteration
             if ( !processingLastNode && itCoords == itBegin ) {
                 itPreviousCoords = itCoords;
                 previousX = x;
                 previousY = y;
             }
 
             // 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 ( tessellate && !isStraight) {
                 mirrorCount = tessellateLineSegment( *itPreviousCoords, previousX, previousY,
                                            *itCoords, x, y,
                                            polygons, viewport,
                                            f, mirrorCount, distance );
             }
 
             else {
                 // special case for polys which cross dateline but have no Tesselation Flag
                 // the expected rendering is a screen coordinates straight line between
                 // points, but in projections with repeatX things are not smooth
                 mirrorCount = crossDateLine( *itPreviousCoords, *itCoords, x, y, polygons, mirrorCount, distance );
             }
 
             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 (isClosed && itCoords == itEnd) {
             itCoords = itBegin;
             processingLastNode = true;
         }
     }
 
     // Closing e.g. in the Antarctica case.
     // This code makes the assumption that
     // - the first node is located at 180 E
     // - and the last node is located at 180 W
     // TODO: add a similar pattern in the crossDateLine() code.
     /*
     GeoDataLatLonAltBox box = lineString.latLonAltBox();
     if( lineString.isClosed() && box.width() == 2*M_PI ) {
         QPolygonF *poly = polygons.last();
         if( box.containsPole( NorthPole ) ) {
             qreal topMargin = 0.0;
             qreal dummy = 0.0;
             q_ptr->screenCoordinates(0.0, q_ptr->maxLat(), viewport, topMargin, dummy );
             poly->push_back( QPointF( poly->last().x(), topMargin ) );
             poly->push_back( QPointF( poly->first().x(), topMargin ) );
         } else {
             qreal bottomMargin = 0.0;
             qreal dummy = 0.0;
             q_ptr->screenCoordinates(0.0, q_ptr->minLat(), viewport, bottomMargin, dummy );
             poly->push_back( QPointF( poly->last().x(), bottomMargin ) );
             poly->push_back( QPointF( poly->first().x(), bottomMargin ) );
         }
     } */
 
     repeatPolygons( viewport, polygons );
 
     return polygons.isEmpty();
 }
 
 void CylindricalProjectionPrivate::translatePolygons( const QVector<QPolygonF *> &polygons,
                                                       QVector<QPolygonF *> &translatedPolygons,
                                                       qreal xOffset )
 {
     // mDebug() << "Translation: " << xOffset;
     translatedPolygons.reserve(polygons.size());
 
     QVector<QPolygonF *>::const_iterator itPolygon = polygons.constBegin();
     QVector<QPolygonF *>::const_iterator itEnd = polygons.constEnd();
 
     for( ; itPolygon != itEnd; ++itPolygon ) {
         QPolygonF * polygon = new QPolygonF;
         *polygon = **itPolygon;
         polygon->translate( xOffset, 0 );
         translatedPolygons.append( polygon );
     }
 }
 
 void CylindricalProjectionPrivate::repeatPolygons( const ViewportParams *viewport,
                                                 QVector<QPolygonF *> &polygons ) const
 {
     Q_Q( const CylindricalProjection );
 
     qreal xEast = 0;
     qreal xWest = 0;
     qreal y = 0;
 
     // Choose a latitude that is inside the viewport.
     const qreal centerLatitude = viewport->viewLatLonAltBox().center().latitude();
 
     const GeoDataCoordinates westCoords(-M_PI, centerLatitude);
     const GeoDataCoordinates eastCoords(+M_PI, centerLatitude);
 
     q->screenCoordinates( westCoords, viewport, xWest, y );
     q->screenCoordinates( eastCoords, viewport, xEast, y );
 
     if ( xWest <= 0 && xEast >= viewport->width() - 1 ) {
         // mDebug() << "No repeats";
         return;
     }
 
     const qreal repeatXInterval = xEast - xWest;
 
     const int repeatsLeft  = (xWest > 0                ) ? (int)(xWest                       / repeatXInterval) + 1 : 0;
     const int repeatsRight = (xEast < viewport->width()) ? (int)((viewport->width() - xEast) / repeatXInterval) + 1 : 0;
 
     QVector<QPolygonF *> repeatedPolygons;
 
     for (int it = repeatsLeft; it > 0; --it) {
         const qreal xOffset = -it * repeatXInterval;
         QVector<QPolygonF *> translatedPolygons;
         translatePolygons( polygons, translatedPolygons, xOffset );
         repeatedPolygons << translatedPolygons;
     }
 
     repeatedPolygons << polygons;
 
     for (int it = 1; it <= repeatsRight; ++it) {
         const qreal xOffset = +it * repeatXInterval;
         QVector<QPolygonF *> translatedPolygons;
         translatePolygons( polygons, translatedPolygons, xOffset );
         repeatedPolygons << translatedPolygons;
     }
 
     polygons = repeatedPolygons;
 
     // mDebug() << "Coordinates: " << xWest << xEast
     //          << "Repeats: " << repeatsLeft << repeatsRight;
 }
 
 qreal CylindricalProjectionPrivate::repeatDistance( const ViewportParams *viewport ) const
 {
     // Choose a latitude that is inside the viewport.
     qreal centerLatitude = viewport->viewLatLonAltBox().center().latitude();
 
     GeoDataCoordinates westCoords( -M_PI, centerLatitude );
     GeoDataCoordinates eastCoords( +M_PI, centerLatitude );
     qreal xWest, xEast, dummyY;
 
     Q_Q( const AbstractProjection );
 
     q->screenCoordinates( westCoords, viewport, xWest, dummyY );
     q->screenCoordinates( eastCoords, viewport, xEast, dummyY );
 
     return   xEast - xWest;
 }
 
 }