Warning, file /education/kstars/kstars/projections/projector.h was not indexed or was modified since last indexation (in which case cross-reference links may be missing, inaccurate or erroneous).

 /*
     SPDX-FileCopyrightText: 2010 Henry de Valence <hdevalence@gmail.com>
 
     SPDX-License-Identifier: GPL-2.0-or-later
 */
 
 #pragma once
 
 #ifdef KSTARS_LITE
 #include "skymaplite.h"
 #else
 #include "skymap.h"
 #endif
 #include "skyobjects/skypoint.h"
 
 #if __GNUC__ > 5
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wignored-attributes"
 #endif
 #if __GNUC__ > 6
 #pragma GCC diagnostic ignored "-Wint-in-bool-context"
 #endif
 #include <Eigen/Core>
 #if __GNUC__ > 5
 #pragma GCC diagnostic pop
 #endif
 
 #include <QPointF>
 
 #include <cstddef>
 #include <cmath>
 
 class KStarsData;
 
 /** This is just a container that holds information needed to do projections. */
 class ViewParams
 {
     public:
         float width, height;
         float zoomFactor;
         bool useRefraction;
         bool useAltAz;
         bool fillGround; ///<If the ground is filled, then points below horizon are invisible
         SkyPoint *focus;
         ViewParams() : width(0), height(0), zoomFactor(0),
             useRefraction(false), useAltAz(false), fillGround(false),
             focus(nullptr) {}
 };
 
 /**
  * @class Projector
  *
  * The Projector class is the primary class that serves as an interface to handle projections.
  */
 class Projector
 {
         Q_GADGET
     public:
         /**
          * Constructor.
          *
          * @param p the ViewParams for this projection
          */
         explicit Projector(const ViewParams &p);
 
         virtual ~Projector() = default;
 
         /** Update cached values for projector */
         void setViewParams(const ViewParams &p);
         ViewParams viewParams() const
         {
             return m_vp;
         }
 
         enum Projection
         {
             Lambert,
             AzimuthalEquidistant,
             Orthographic,
             Equirectangular,
             Stereographic,
             Gnomonic,
             UnknownProjection
         };
         Q_ENUM(Projection)
 
         /** Return the type of this projection */
         Q_INVOKABLE virtual Projection type() const = 0;
 
         /** Return the FOV of this projection */
         double fov() const;
 
         /**
          * Check if the current point on screen is a valid point on the sky. This is needed
          * to avoid a crash of the program if the user clicks on a point outside the sky (the
          * corners of the sky map at the lowest zoom level are the invalid points).
          * @param p the screen pixel position
          */
         virtual bool unusablePoint(const QPointF &p) const;
 
         /**
          * Given the coordinates of the SkyPoint argument, determine the
          * pixel coordinates in the SkyMap.
          *
          * Since most of the projections used by KStars are very similar,
          * if this function were to be reimplemented in each projection subclass
          * we would end up changing maybe 5 or 6 lines out of 150.
          * Instead, we have a default implementation that uses the projectionK
          * and projectionL functions to take care of the differences between
          * e.g. Orthographic and Stereographic. There is also the cosMaxFieldAngle
          * function, which is used for testing whether a point is on the visible
          * part of the projection, and the radius function which gives the radius of
          * the projection in screen coordinates.
          *
          * While this seems ugly, it is less ugly than duplicating 150 loc to change 5.
          *
          * @return Eigen::Vector2f containing screen pixel x, y coordinates of SkyPoint.
          * @param o pointer to the SkyPoint for which to calculate x, y coordinates.
          * @param oRefract true = use Options::useRefraction() value.
          *   false = do not use refraction.  This argument is only needed
          *   for the Horizon, which should never be refracted.
          * @param onVisibleHemisphere pointer to a bool to indicate whether the point is
          *   on the visible part of the Celestial Sphere.
          */
         virtual Eigen::Vector2f toScreenVec(const SkyPoint *o, bool oRefract = true,
                                             bool *onVisibleHemisphere = nullptr) const;
 
         /**
          * This is exactly the same as toScreenVec but it returns a QPointF.
          * It just calls toScreenVec and converts the result.
          * @see toScreenVec()
          */
         QPointF toScreen(const SkyPoint *o, bool oRefract = true, bool *onVisibleHemisphere = nullptr) const;
 
         /**
          * @short Determine RA, Dec coordinates of the pixel at (dx, dy), which are the
          * screen pixel coordinate offsets from the center of the Sky pixmap.
          * @param p the screen pixel position to convert
          * @param LST pointer to the local sidereal time, as a dms object.
          * @param lat pointer to the current geographic laitude, as a dms object
          * @param onlyAltAz the returned SkyPoint's RA & DEC are not computed, only Alt/Az.
          */
         virtual SkyPoint fromScreen(const QPointF &p, dms *LST, const dms *lat, bool onlyAltAz = false) const;
 
         /**
          * ASSUMES *p1 did not clip but *p2 did.  Returns the QPointF on the line
          * between *p1 and *p2 that just clips.
          */
         QPointF clipLine(SkyPoint *p1, SkyPoint *p2) const;
 
         /**
          * ASSUMES *p1 did not clip but *p2 did.  Returns the Eigen::Vector2f on the line
          * between *p1 and *p2 that just clips.
          */
         Eigen::Vector2f clipLineVec(SkyPoint *p1, SkyPoint *p2) const;
 
         /** Check whether the projected point is on-screen */
         bool onScreen(const QPointF &p) const;
         bool onScreen(const Eigen::Vector2f &p) const;
 
         /**
          * @short Determine if the skypoint p is likely to be visible in the display window.
          *
          * checkVisibility() is an optimization function.  It determines whether an object
          * appears within the bounds of the skymap window, and therefore should be drawn.
          * The idea is to save time by skipping objects which are off-screen, so it is
          * absolutely essential that checkVisibility() is significantly faster than
          * the computations required to draw the object to the screen.
          *
          * If the ground is to be filled, the function first checks whether the point is
          * below the horizon, because they will be covered by the ground anyways.
          * Importantly, it does not call the expensive EquatorialToHorizontal function.
          * This means that the horizontal coordinates MUST BE CORRECT! The vast majority
          * of points are already synchronized, so recomputing the horizontal coordinates is
          * a waste.
          *
          * The function then checks the difference between the Declination/Altitude
          * coordinate of the Focus position, and that of the point p.  If the absolute
          * value of this difference is larger than fov, then the function returns false.
          * For most configurations of the sky map window, this simple check is enough to
          * exclude a large number of objects.
          *
          * Next, it determines if one of the poles of the current Coordinate System
          * (Equatorial or Horizontal) is currently inside the sky map window.  This is
          * stored in the member variable 'bool SkyMap::isPoleVisible, and is set by the
          * function SkyMap::setMapGeometry(), which is called by SkyMap::paintEvent().
          * If a Pole is visible, then it will return true immediately.  The idea is that
          * when a pole is on-screen it is computationally expensive to determine whether
          * a particular position is on-screen or not: for many valid Dec/Alt values, *all*
          * values of RA/Az will indeed be onscreen, but for other valid Dec/Alt values,
          * only *most* RA/Az values are onscreen.  It is cheaper to simply accept all
          * "horizontal" RA/Az values, since we have already determined that they are
          * on-screen in the "vertical" Dec/Alt coordinate.
          *
          * Finally, if no Pole is onscreen, it checks the difference between the Focus
          * position's RA/Az coordinate and that of the point p.  If the absolute value of
          * this difference is larger than XMax, the function returns false.  Otherwise,
          * it returns true.
          *
          * @param p pointer to the skypoint to be checked.
          * @return true if the point p was found to be inside the Sky map window.
          * @see SkyMap::setMapGeometry()
          * @see SkyMap::fov()
          * @note If you are creating skypoints using equatorial coordinates, then
          * YOU MUST CALL EQUATORIALTOHORIZONTAL BEFORE THIS FUNCTION!
          */
         bool checkVisibility(const SkyPoint *p) const;
 
         /**
          * Determine the on-screen position angle of a SkyPont with recept with NCP.
          * This is the object's sky position angle (w.r.t. North).
          * of "North" at the position of the object (w.r.t. the screen Y-axis).
          * The latter is determined by constructing a test point with the same RA but
          * a slightly increased Dec as the object, and calculating the angle w.r.t. the
          * Y-axis of the line connecting the object to its test point.
          */
         double findNorthPA(const SkyPoint *o, float x, float y) const;
 
         /**
          * Determine the on-screen position angle of a SkyObject.  This is the sum
          * of the object's sky position angle (w.r.t. North), and the position angle
          * of "North" at the position of the object (w.r.t. the screen Y-axis).
          * The latter is determined by constructing a test point with the same RA but
          * a slightly increased Dec as the object, and calculating the angle w.r.t. the
          * Y-axis of the line connecting the object to its test point.
          */
         double findPA(const SkyObject *o, float x, float y) const;
 
         /**
          * Get the ground polygon
          * @param labelpoint This point will be set to something suitable for attaching a label
          * @param drawLabel this tells whether to draw a label.
          * @return the ground polygon
          */
         virtual QVector<Eigen::Vector2f> groundPoly(SkyPoint *labelpoint = nullptr, bool *drawLabel = nullptr) const;
 
         /**
          * @brief updateClipPoly calculate the clipping polygen given the current FOV.
          */
         virtual void updateClipPoly();
 
         /**
          * @return the clipping polygen covering the visible sky area. Anything outside this polygon is
          * clipped by QPainter.
          */
         virtual QPolygonF clipPoly() const;
 
     protected:
         /**
          * Get the radius of this projection's sky circle.
          * @return the radius in radians
          */
         virtual double radius() const
         {
             return 2 * M_PI;
         }
 
         /**
          * This function handles some of the projection-specific code.
          * @see toScreen()
          */
         virtual double projectionK(double x) const
         {
             return x;
         }
 
         /**
          * This function handles some of the projection-specific code.
          * @see toScreen()
          */
         virtual double projectionL(double x) const
         {
             return x;
         }
 
         /**
          * This function returns the cosine of the maximum field angle, i.e., the maximum angular
          * distance from the focus for which a point should be projected. Default is 0, i.e.,
          * 90 degrees.
          */
         virtual double cosMaxFieldAngle() const
         {
             return 0;
         }
 
         /**
          * Helper function for drawing ground.
          * @return the point with Alt = 0, az = @p az
          */
         static SkyPoint pointAt(double az);
 
         KStarsData *m_data { nullptr };
         ViewParams m_vp;
         double m_sinY0 { 0 };
         double m_cosY0 { 0 };
         double m_fov { 0 };
         QPolygonF m_clipPolygon;
 
     private:
         //Used by CheckVisibility
         double m_xrange { 0 };
         bool m_isPoleVisible { false };
 };