add initial support for parallax effect

Author: henrysky

src/core/StelCore.cpp

@@ -82,6 +82,8 @@ StelCore::StelCore()
 	, flagUseNutation(true)
 	, flagUseAberration(true)
 	, aberrationFactor(1.0)
+	, flagUseParallax(true)
+	, parallaxFactor(1.0)
 	, flagUseTopocentricCoordinates(true)
 	, timeSpeed(JD_SECOND)
 	, JD(0.,0.)
@@ -141,6 +143,8 @@ StelCore::StelCore()
 	flagUseNutation=conf->value("astro/flag_nutation", true).toBool();
 	flagUseAberration=conf->value("astro/flag_aberration", true).toBool();
 	aberrationFactor=conf->value("astro/aberration_factor", 1.0).toDouble();
+	flagUseParallax=conf->value("astro/flag_parallax", true).toBool();
+	parallaxFactor=conf->value("astro/parallax_factor", 1.0).toDouble();
 	flagUseTopocentricCoordinates=conf->value("astro/flag_topocentric_coordinates", true).toBool();
 	flagUseDST=conf->value("localization/flag_dst", true).toBool();
 

src/core/StelCore.hpp

@@ -55,6 +55,8 @@ class StelCore : public QObject
 	Q_PROPERTY(bool flagUseNutation READ getUseNutation WRITE setUseNutation NOTIFY flagUseNutationChanged)
 	Q_PROPERTY(bool flagUseAberration READ getUseAberration WRITE setUseAberration NOTIFY flagUseAberrationChanged)
 	Q_PROPERTY(double aberrationFactor READ getAberrationFactor WRITE setAberrationFactor NOTIFY aberrationFactorChanged)
+	Q_PROPERTY(bool flagUseParallax READ getUseParallax WRITE setUseParallax NOTIFY flagUseParallaxChanged)
+	Q_PROPERTY(double parallaxFactor READ getParallaxFactor WRITE setParallaxFactor NOTIFY parallaxFactorChanged)
 	Q_PROPERTY(bool flagUseTopocentricCoordinates READ getUseTopocentricCoordinates WRITE setUseTopocentricCoordinates NOTIFY flagUseTopocentricCoordinatesChanged)
 	Q_PROPERTY(ProjectionType currentProjectionType READ getCurrentProjectionType WRITE setCurrentProjectionType NOTIFY currentProjectionTypeChanged)
 	//! This is just another way to access the projection type, by string instead of enum
@@ -551,6 +553,16 @@ public slots:
 	QByteArray getAberrationShader() const;
 	void setAberrationUniforms(QOpenGLShaderProgram& program) const;
 
+	//! @return whether parallax effect is currently used.
+	bool getUseParallax() const {return flagUseParallax;}
+	//! Set whether you want computation and simulation of parallax effect.
+	void setUseParallax(bool use) { if (flagUseParallax != use) { flagUseParallax=use; StelApp::immediateSave("astro/flag_parallax", use); emit flagUseParallaxChanged(use); }}
+
+	//! @return parallax factor. 1 is realistic simulation, but higher values may be useful for didactic purposes.
+	double getParallaxFactor() const {return parallaxFactor;}
+	//! Set aberration factor. Values are clamped to 0...5. (Values above 5 cause graphical problems.)
+	void setParallaxFactor(double factor) { if (!fuzzyEquals(parallaxFactor, factor)) { parallaxFactor=qBound(0.,factor, 1000.); StelApp::immediateSave("astro/parallax_factor", parallaxFactor); emit parallaxFactorChanged(factor); }}
+
 	//! @return whether topocentric coordinates are currently used.
 	bool getUseTopocentricCoordinates() const {return flagUseTopocentricCoordinates;}
 	//! Set whether you want topocentric or planetocentric data
@@ -862,6 +874,10 @@ public slots:
 	void flagUseAberrationChanged(bool b);
 	//! This signal indicates a change in aberration exaggeration factor
 	void aberrationFactorChanged(double val);
+	//! This signal indicates a switch in use of parallax
+	void flagUseParallaxChanged(bool b);
+	//! This signal indicates a change in parallax exaggeration factor
+	void parallaxFactorChanged(double val);
 	//! This signal indicates a switch in use of topocentric coordinates
 	void flagUseTopocentricCoordinatesChanged(bool b);
 	//! Emitted whenever the projection type changes
@@ -943,6 +959,10 @@ private slots:
 	bool flagUseAberration;
 	// value to allow exaggerating aberration effects. 1 is natural value, stretching to e.g. 1000 may be useful for explanations.
 	double aberrationFactor;
+	// flag to indicate we want to include parallax effect
+	bool flagUseParallax;
+	// value to allow exaggerating parallax effects. 1 is natural value, stretching to e.g. 1000 may be useful for explanations.
+	double parallaxFactor;
 	// flag to indicate that we show topocentrically corrected coordinates. (Switching to false for planetocentric coordinates is new for 0.14)
 	bool flagUseTopocentricCoordinates;
 

src/core/modules/Star.hpp

@@ -235,6 +235,18 @@ struct Star
          DE    = getX1() + dyrs * getDx1() * MAS2RAD;
       }
    }
+
+   //to get new 3D cartesian position for parallax effect given current star 3D cartesian position, planet orbital period and radius and current delta time from catalog epoch
+   inline void getPlxEffect(double plx, Vec3f& bS, double operiod, double oradius, double dyrs) const {
+		if (plx <= 0) return;
+		Vec3d bSd(bS[0], bS[1], bS[2]);
+		bSd.normalize();
+		bSd *= 1000./ plx;
+		// remainder of dt in dyrs divided by period
+		double dt = fmod(dyrs, operiod);  // to get phase of the orbit
+		Vec3d b0Ecl(oradius * cos(2 * M_PI / operiod * dt), oradius * sin(2 * M_PI / operiod * dt), 0.);
+		bS = (bSd + b0Ecl * MAS2RAD * 1000.).toVec3f();
+   }
 };
 
 struct Star1 : public Star<Star1>

src/core/modules/StarMgr.cpp

@@ -1242,12 +1242,16 @@ void StarMgr::draw(StelCore* core)
 				maxMagStarName = x;
 		}
 		int zone;
+		const double withParallax = core->getUseParallax() * core->getParallaxFactor();
+		double orbital_period = core->getCurrentPlanet()->getSiderealPeriod() / 365.25;  // in earth years
+		// get orbital_radius in AU using Kepler's third law
+		double orbital_radius = pow(orbital_period, 2.0/3.0);
 		for (GeodesicSearchInsideIterator it1(*geodesic_search_result,z->level);(zone = it1.next()) >= 0;)
-			z->draw(&sPainter, zone, true, rcmag_table, limitMagIndex, core, maxMagStarName, names_brightness, viewportCaps, withAberration, velf);
+			z->draw(&sPainter, zone, true, rcmag_table, limitMagIndex, core, maxMagStarName, names_brightness, viewportCaps, withAberration, velf, withParallax, orbital_period, orbital_radius);
 		for (GeodesicSearchBorderIterator it1(*geodesic_search_result,z->level);(zone = it1.next()) >= 0;)
-			z->draw(&sPainter, zone, false, rcmag_table, limitMagIndex, core, maxMagStarName,names_brightness, viewportCaps, withAberration, velf);
+			z->draw(&sPainter, zone, false, rcmag_table, limitMagIndex, core, maxMagStarName,names_brightness, viewportCaps, withAberration, velf, withParallax, orbital_period, orbital_radius);
 		// always check the last zone because it is a global zone
-		z->draw(&sPainter, (20<<(z->level<<1)), false, rcmag_table, limitMagIndex, core, maxMagStarName, names_brightness, viewportCaps, withAberration, velf);
+		z->draw(&sPainter, (20<<(z->level<<1)), false, rcmag_table, limitMagIndex, core, maxMagStarName, names_brightness, viewportCaps, withAberration, velf, withParallax, orbital_period, orbital_radius);
 	}
 	exit_loop:
 

src/core/modules/StarWrapper.cpp

@@ -383,6 +383,13 @@ QString StarWrapper1::getInfoString(const StelCore *core, const InfoStringGroup&
 	{
 		if (Plx!=0)
 		{
+			// get orbital_radius in AU using Kepler's third law, in case we are not on Earth
+			if (core->getCurrentPlanet()->getID() != "earth") {
+				double orbital_radius = pow(core->getCurrentPlanet()->getSiderealPeriod() / 365.25, 2.0/3.0);  // in AU
+				Plx *= orbital_radius;
+				PlxErr *= orbital_radius;
+			}
+			
 			QString plx = q_("Parallax");
 			if (PlxErr>0.f)
 				oss <<  QString("%1: %2%3%4 ").arg(plx, QString::number(Plx, 'f', 3), QChar(0x00B1), QString::number(PlxErr, 'f', 3));

src/core/modules/ZoneArray.cpp

@@ -425,7 +425,7 @@ template<class Star>
 void SpecialZoneArray<Star>::draw(StelPainter* sPainter, int index, bool isInsideViewport, const RCMag* rcmag_table,
 				  int limitMagIndex, StelCore* core, int maxMagStarName, float names_brightness,
 				  const QVector<SphericalCap> &boundingCaps,
-				  const bool withAberration, const Vec3f vel) const
+				  const bool withAberration, const Vec3f vel, const double withParallax, double operiod, double oradius) const
 {
 	StelSkyDrawer* drawer = core->getSkyDrawer();
 	Vec3f vf;
@@ -466,16 +466,17 @@ void SpecialZoneArray<Star>::draw(StelPainter* sPainter, int index, bool isInsid
 
 		// only recompute if has time dependence and time is far away
 		bool recomputeMag = (s->getPreciseAstrometricFlag() && (fabs(dyrs) > 5000.));
+		double Plx = s->getPlx();
 		if (recomputeMag) { 
 			// don't do full solution, can be very slow, just estimate here	
 			// estimate parallax from radial velocity and total proper motion
-			double Plx = s->getPlx();
 			double vr = s->getRV();
 			Vec3d pmvec0(s->getDx0(), s->getDx1(), s->getDx2());
 			pmvec0 = pmvec0 * MAS2RAD;
 			double pmr0 = vr * Plx / (AU / JYEAR_SECONDS) * MAS2RAD;
 			double pmtotsqr =  (pmvec0[0] * pmvec0[0] + pmvec0[1] * pmvec0[1] + pmvec0[2] * pmvec0[2]);
 			double f = 1. / sqrt(1. + 2. * pmr0 * dyrs + (pmtotsqr + pmr0*pmr0)*dyrs*dyrs);
+			Plx *= f;
 			float magOffset = 5.f * log10(1/f);
 			starMag += magOffset * 1000.;
 			// if we reach here we might as well compute the position too
@@ -498,6 +499,10 @@ void SpecialZoneArray<Star>::draw(StelPainter* sPainter, int index, bool isInsid
 			s->getJ2000Pos(dyrs, vf);
 		}
 
+		if (withParallax) {
+			s->getPlxEffect(withParallax * Plx, vf, operiod, oradius, dyrs);
+		}
+
 		// Aberration: vf contains Equatorial J2000 position.
 		if (withAberration)
 		{

src/core/modules/ZoneArray.hpp

@@ -110,7 +110,7 @@ class ZoneArray
 					  const RCMag* rcmag_table, int limitMagIndex, StelCore* core,
 					  int maxMagStarName, float names_brightness,
 					  const QVector<SphericalCap>& boundingCaps,
-					  const bool withAberration, const Vec3f vel) const = 0;
+					  const bool withAberration, const Vec3f vel, const double withParallax, double operiod, double oradius) const = 0;
 
 	//! Get whether or not the catalog was successfully loaded.
 	//! @return @c true if at least one zone was loaded, otherwise @c false
@@ -182,7 +182,7 @@ class SpecialZoneArray : public ZoneArray
 	          const RCMag *rcmag_table, int limitMagIndex, StelCore* core,
 	          int maxMagStarName, float names_brightness,
 	          const QVector<SphericalCap>& boundingCaps,
-	          const bool withAberration, const Vec3f vel) const override;
+	          const bool withAberration, const Vec3f vel, const double withParallax, double operiod, double oradius) const override;
 
 	void searchAround(const StelCore* core, int index,const Vec3d &v,double cosLimFov,
 	                  QList<StelObjectP > &result) override;

src/gui/ConfigurationDialog.cpp

@@ -209,6 +209,8 @@ void ConfigurationDialog::createDialogContent()
 	connectBoolProperty(ui->nutationCheckBox, "StelCore.flagUseNutation");
 	connectBoolProperty(ui->aberrationCheckBox, "StelCore.flagUseAberration");
 	connectDoubleProperty(ui->aberrationSpinBox, "StelCore.aberrationFactor");
+	connectBoolProperty(ui->parallaxCheckBox, "StelCore.flagUseParallax");
+	connectDoubleProperty(ui->parallaxSpinBox, "StelCore.parallaxFactor");
 	connectBoolProperty(ui->topocentricCheckBox, "StelCore.flagUseTopocentricCoordinates");
 
 	// Additional settings for selected object info
@@ -1088,6 +1090,8 @@ void ConfigurationDialog::saveAllSettings()
 	conf->setValue("astro/flag_nutation",			core->getUseNutation());
 	conf->setValue("astro/flag_aberration",			core->getUseAberration());
 	conf->setValue("astro/aberration_factor",		core->getAberrationFactor());
+	conf->setValue("astro/flag_parallax",			core->getUseParallax());
+	conf->setValue("astro/parallax_factor",		core->getParallaxFactor());
 	conf->setValue("astro/flag_topocentric_coordinates",	core->getUseTopocentricCoordinates());
 	conf->setValue("astro/solar_system_threads",		propMgr->getStelPropertyValue("SolarSystem.extraThreads").toInt());
 

src/gui/configurationDialog.ui

@@ -2203,11 +2203,47 @@
                </property>
               </widget>
              </item>
-             <item row="0" column="3" rowspan="2">
+             <item row="0" column="3" rowspan="3">
               <layout class="QGridLayout" name="gridLayoutInclude">
                <property name="spacing">
                 <number>0</number>
                </property>
+               <item row="2" column="1">
+                <layout class="QHBoxLayout" name="horizontalLayout_IncludeParallax">
+                 <item>
+                  <widget class="QCheckBox" name="parallaxCheckBox">
+                   <property name="toolTip">
+                    <string>Parallax is the apparent shift in the position of an object when viewed from two different points.</string>
+                   </property>
+                   <property name="text">
+                    <string>Parallax</string>
+                   </property>
+                  </widget>
+                 </item>
+                 <item>
+                  <widget class="QDoubleSpinBox" name="parallaxSpinBox">
+                   <property name="toolTip">
+                    <string>Exaggerate parallax (for didactic explanations)</string>
+                   </property>
+                   <property name="decimals">
+                    <number>1</number>
+                   </property>
+                   <property name="minimum">
+                    <double>1.000000000000000</double>
+                   </property>
+                   <property name="maximum">
+                    <double>1000.000000000000000</double>
+                   </property>
+                   <property name="singleStep">
+                    <double>1.000000000000000</double>
+                   </property>
+                   <property name="value">
+                    <double>1.000000000000000</double>
+                   </property>
+                  </widget>
+                 </item>
+                </layout>
+               </item>
                <item row="1" column="2">
                 <layout class="QHBoxLayout" name="horizontalLayout_IncludeNutAberr">
                  <item>