Fix stellar appearance of lunar occultation

src/core/modules/Planet.cpp

@@ -3765,7 +3765,7 @@ float Planet::getVMagnitude(const StelCore* core, double eclipseFactor) const
 double Planet::getAngularRadius(const StelCore* core) const
 {
 	const double rad = (rings ? rings->getSize() : equatorialRadius);
-	return std::atan2(rad*sphereScale,getJ2000EquatorialPos(core).norm()) * M_180_PI;
+	return std::asin(rad*sphereScale/getJ2000EquatorialPos(core).norm()) * M_180_PI;
 }
 
 

src/core/modules/StarMgr.cpp

@@ -46,6 +46,7 @@
 #include "StelUtils.hpp"
 #include "StelHealpix.hpp"
 #include "StelObject.hpp"
+#include "SolarSystem.hpp"
 
 #include <QGlobalStatic>
 #include <QTextStream>
@@ -1325,117 +1326,131 @@
 
 
 // Draw all the stars
 void StarMgr::draw(StelCore* core)
 {
 	const StelProjectorP prj = core->getProjection(StelCore::FrameJ2000);
 	StelSkyDrawer* skyDrawer = core->getSkyDrawer();
 	// If stars are turned off don't waste time below
 	// projecting all stars just to draw disembodied labels
 	if (!static_cast<bool>(starsFader.getInterstate()))
 		return;
 
 	static StelSkyCultureMgr* scMgr = GETSTELMODULE(StelSkyCultureMgr);
 	const bool currentSkycultureUsesCommonStarnames=scMgr->getFlagOverrideUseCommonNames() ||
 							scMgr->currentSkycultureUsesCommonNames();
 
 	int maxSearchLevel = getMaxSearchLevel();
 	double margin = 0.;  // pixel margin to be applied to viewport convex polygon
 	if (core->getSkyDrawer()->getFlagHasAtmosphere())
 	{
 		// Saemundsson's inversion formula for atmospheric refraction is not exact, so need some padding in terms of arcseconds
 		margin = 30000. * MAS2RAD * prj->getPixelPerRadAtCenter();  // 0.5 arcmin
 	}
 
 	QVector<SphericalCap> viewportCaps = prj->getViewportConvexPolygon(margin, margin)->getBoundingSphericalCaps();
 	viewportCaps.append(core->getVisibleSkyArea());
 	const GeodesicSearchResult* geodesic_search_result = core->getGeodesicGrid(maxSearchLevel)->search(viewportCaps,maxSearchLevel);
 
 	// Set temporary static variable for optimization
 	const float names_brightness = labelsFader.getInterstate() * starsFader.getInterstate();
 
 	// prepare for aberration: Explan. Suppl. 2013, (7.38)
 	const bool withAberration=core->getUseAberration();
 	Vec3d vel(0.);
 	if (withAberration)
 	{
 		vel = core->getAberrationVec(core->getJDE());
 	}
 
 	// Prepare openGL for drawing many stars
 	StelPainter sPainter(prj);
 	QFont font=QGuiApplication::font();
 	font.setPixelSize(fontSize);
 	sPainter.setFont(font);
 
 	skyDrawer->preDrawPointSource(&sPainter);
 
 	// Prepare a table for storing precomputed RCMag for all ZoneArrays
 	RCMag rcmag_table[RCMAG_TABLE_SIZE];
+
+	// Try to filter away stars hidden by the Moon!
+	bool filterMoon=false;
+	PlanetP moon = GETSTELMODULE(SolarSystem)->getMoon();
+	Vec3d moonPos=moon->getJ2000EquatorialPos(core);
+	const double moonRadius = moon->getEquatorialRadius() * moon->getSphereScale();
+	double angularSize = asin(moonRadius / moonPos.norm());
+	moonPos.normalize();
+	SphericalCap moonCap(moonPos, cos(angularSize));
+	for (auto  &cap : viewportCaps)
+	{
+	    if (cap.intersects(moonCap))
+		filterMoon=true;
+	}
 
 	// Draw all the stars of all the selected zones
 	for (const auto* z : std::as_const(gridLevels))
 	{
 		int limitMagIndex=RCMAG_TABLE_SIZE;
 		// overshoot by 7 mag because some stars (like HIP 16757) can get brighter than its catalogs min magnitude
 		const float mag_min = 0.001f*z->mag_min - 7.f;
 		for (int i=0;i<RCMAG_TABLE_SIZE;++i)
 		{
 			const float mag = mag_min+0.05*i;  // 0.05 mag MagStepIncrement
 			if (skyDrawer->computeRCMag(mag, &rcmag_table[i])==false)
 			{
 				if (i==0)
 					goto exit_loop;
 
 				// The last magnitude at which the star is visible
 				limitMagIndex = i-1;
 
 				// We reached the point where stars are not visible anymore
 				// Fill the rest of the table with zero and leave.
 				for (;i<RCMAG_TABLE_SIZE;++i)
 				{
 					rcmag_table[i].luminance=0;
 					rcmag_table[i].radius=0;
 				}
 				break;
 			}
 			rcmag_table[i].radius *= starsFader.getInterstate();
 		}
 		lastMaxSearchLevel = z->level;
 
 		int maxMagStarName = 0;
 		if (labelsFader.getInterstate()>0.f)
 		{
 			// Adapt magnitude limit of the stars labels according to FOV and labelsAmount
 			float maxMag = (skyDrawer->getLimitMagnitude()-6.5f)*0.7f+(static_cast<float>(labelsAmount)*1.2f)-2.f;
 			int x = static_cast<int>((maxMag-mag_min)/0.05);  // 0.05 mag MagStepIncrement
 			if (x > 0)
 				maxMagStarName = x;
 		}
 		int zone;
 		double withParallax = core->getUseParallax() * core->getParallaxFactor();
 		Vec3d diffPos(0., 0., 0.);
 		if (withParallax) {
 			diffPos = core->getParallaxDiff(core->getJDE());
 		}
 		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, vel, withParallax, diffPos, currentSkycultureUsesCommonStarnames);
+			z->draw(&sPainter, zone, true, rcmag_table, limitMagIndex, core, maxMagStarName, names_brightness, viewportCaps, withAberration, vel, withParallax, diffPos, currentSkycultureUsesCommonStarnames, filterMoon, moonCap);
 		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, vel, withParallax, diffPos, currentSkycultureUsesCommonStarnames);
+			z->draw(&sPainter, zone, false, rcmag_table, limitMagIndex, core, maxMagStarName,names_brightness, viewportCaps, withAberration, vel, withParallax, diffPos, currentSkycultureUsesCommonStarnames, filterMoon, moonCap);
 		// 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, vel, withParallax, diffPos, currentSkycultureUsesCommonStarnames);
+		z->draw(&sPainter, (20<<(z->level<<1)), false, rcmag_table, limitMagIndex, core, maxMagStarName, names_brightness, viewportCaps, withAberration, vel, withParallax, diffPos, currentSkycultureUsesCommonStarnames, filterMoon, moonCap);
 	}
 	exit_loop:
 
 	// Finish drawing many stars
 	skyDrawer->postDrawPointSource(&sPainter);
 
 	if (objectMgr->getFlagSelectedObjectPointer())
 		drawPointer(sPainter, core);
 }
 
 
 // Return a QList containing the stars located
 // inside the limFov circle around position vv (in J2000 frame without aberration)
 QList<StelObjectP > StarMgr::searchAround(const Vec3d& vv, double limFov, const StelCore* core) const
 {
 	QList<StelObjectP > result;

src/core/modules/ZoneArray.cpp

@@ -433,7 +433,8 @@ void SpecialZoneArray<Star>::draw(StelPainter* sPainter, int index, bool isInsid
 				  int limitMagIndex, StelCore* core, int maxMagStarName, float names_brightness,
 				  const QVector<SphericalCap> &boundingCaps,
 				  const bool withAberration, const Vec3d vel, const double withParallax, const Vec3d diffPos,
-				  const bool withCommonNameI18n) const
+				  const bool withCommonNameI18n,
+				  const bool filterMoon, SphericalCap moonCap) const
 {
 	StelSkyDrawer* drawer = core->getSkyDrawer();
 	Vec3d v;
@@ -543,6 +544,13 @@ void SpecialZoneArray<Star>::draw(StelPainter* sPainter, int index, bool isInsid
 				continue;
 		}
 
+		// If the star is covered by the Moon, don't draw (avoid displaying part of halo of occulted star!)
+		// TODO: This is a bad test. We should draw the moon into a stencil buffer and check that.
+		if (filterMoon)
+		{
+			if (moonCap.contains(v))
+				continue;
+		}
 		int extinctedMagIndex = magIndex;
 		float twinkleFactor=1.0f; // allow height-dependent twinkle.
 		if (withExtinction)

src/core/modules/ZoneArray.hpp

@@ -100,7 +100,7 @@ class ZoneArray
 	virtual void searchWithin(const StelCore* core, int index, const SphericalRegionP region, const double withParallax, const Vec3d diffPos, const bool hipOnly, const float maxMag,
 							  QList<StelObjectP > &result) const = 0;
 
-    virtual StelObjectP searchGaiaID(int index, const StarId source_id, int& matched) const = 0;
+	virtual StelObjectP searchGaiaID(int index, const StarId source_id, int& matched) const = 0;
 	virtual void searchGaiaIDepochPos(const StarId source_id, float dyrs,
                                                   double & RA,
                                                   double & DEC,
@@ -114,7 +114,9 @@ class ZoneArray
 					  const RCMag* rcmag_table, int limitMagIndex, StelCore* core,
 					  int maxMagStarName, float names_brightness,
 					  const QVector<SphericalCap>& boundingCaps,
-					  const bool withAberration, const Vec3d vel, const double withParallax, const Vec3d diffPos, const bool withCommonNameI18n) const = 0;
+					  const bool withAberration, const Vec3d vel,
+					  const double withParallax, const Vec3d diffPos, const bool withCommonNameI18n,
+					  const bool filterMoon, SphericalCap moonCap) const = 0;
 
 	//! Get whether or not the catalog was successfully loaded.
 	//! @return @c true if at least one zone was loaded, otherwise @c false
@@ -187,7 +189,8 @@ 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 Vec3d vel, const double withParallax, const Vec3d diffPos, const bool withCommonNameI18n) const override;
+		  const bool withAberration, const Vec3d vel, const double withParallax, const Vec3d diffPos, const bool withCommonNameI18n,
+		  const bool filterMoon, SphericalCap moonCap) const override;
 
 	void searchAround(const StelCore* core, int index, const Vec3d &v, const double withParallax, 
 					  const Vec3d diffPos, double cosLimFov, QList<StelObjectP > &result) override;