15291801018

Committed 28 May 2025 04:52AM UTC coverage: 11.931% (-0.02%) from 11.951%

Build # 15291801018

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push

github

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alex-w

Commit Message

Added new set of navigational stars (XIX century)

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2.89

/src/core/modules/Comet.cpp

/*
 * Stellarium
 * Copyright (C) 2010 Bogdan Marinov
 * Copyright (C) 2014 Georg Zotti (Tails)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA  02110-1335, USA.
 */
 
#include "Comet.hpp"
#include "Orbit.hpp"
#include "SolarSystem.hpp"

#include "StelApp.hpp"
#include "StelCore.hpp"
#include "StelPainter.hpp"

#include "StelTexture.hpp"
#include "StelToneReproducer.hpp"
#include "StelTranslator.hpp"
#include "StelUtils.hpp"
#include "StelMovementMgr.hpp"
#include "StelModuleMgr.hpp"
#include "LandscapeMgr.hpp"

#include <QDebug>
#include <QElapsedTimer>

// for compute tail shape
#define COMET_TAIL_SLICES 16u // segments around the perimeter
#define COMET_TAIL_STACKS 16u // cuts along the rotational axis

// These are to avoid having index arrays for each comet when all are equal.
bool Comet::createTailIndices=true;
bool Comet::createTailTextureCoords=true;
StelTextureSP Comet::comaTexture;
StelTextureSP Comet::tailTexture;
QVector<Vec2f> Comet::tailTexCoordArr; // computed only once for all Comets.
QVector<unsigned short> Comet::tailIndices; // computed only once for all Comets.

Comet::Comet(const QString& englishName,
             double radius,
             double oblateness,
             Vec3f halocolor,
             float albedo,
             float roughness,
             float outgas_intensity,
             float outgas_falloff,
             const QString& atexMapName,
             const QString& aobjModelName,
             posFuncType coordFunc,
             KeplerOrbit* orbitPtr,
             OsculatingFunctType *osculatingFunc,
             bool acloseOrbit,
             bool hidden,
             const QString& pTypeStr,
             float dustTailWidthFact,
             float dustTailLengthFact,
             float dustTailBrightnessFact)
        : Planet (englishName,
                  radius,
                  oblateness,
                  halocolor,
                  albedo,
                  roughness,
                  atexMapName,
                  "", // no normalmap.
                  "", // no horizon map
                  aobjModelName,
                  coordFunc,
                  orbitPtr,
                  osculatingFunc,
                  acloseOrbit,
                  hidden,
                  false, //No atmosphere
                  true, //halo
                  pTypeStr),
          slopeParameter(-10.f), // -10 == uninitialized: used in getVMagnitude()
          isCometFragment(false),
          iauDesignation(QString()),
          extraDesignations(),
          extraDesignationsHtml(),
          tailFactors(-1., -1.), // mark "invalid"
          tailActive(false),
          tailBright(false),
          deltaJDEtail(15.0*StelCore::JD_MINUTE), // update tail geometry every 15 minutes only
          lastJDEtail(0.0),
          dustTailWidthFactor(dustTailWidthFact),
          dustTailLengthFactor(dustTailLengthFact),
          dustTailBrightnessFactor(dustTailBrightnessFact),
          intensityFovScale(1.0f),
          intensityMinFov(0.001f), // when zooming in further, Coma is no longer visible.
          intensityMaxFov(0.010f) // when zooming out further, Coma is fully visible (when enabled).
{
        this->outgas_intensity =outgas_intensity;
        this->outgas_falloff   =outgas_falloff;

        gastailVertexArr.clear();
        dusttailVertexArr.clear();
        comaVertexArr.clear();
        gastailColorArr.clear();
        dusttailColorArr.clear();

        //TODO: Name processing?
}

Comet::~Comet()
{
}

void Comet::setAbsoluteMagnitudeAndSlope(const float magnitude, const float slope)
{
        if ((slope < -2.5f) || (slope > 25.0f))
        {
                // Slope G can become slightly smaller than 0. -10 is mark of invalidity.
                qWarning().noquote() << "Suspect slope parameter value" << slope << "for comet" << getEnglishName() << "(rarely exceeding -1...20)";
                return;
        }
        absoluteMagnitude = magnitude;
        slopeParameter = slope;
}

void Comet::translateName(const StelTranslator &translator)
{
        static const QRegularExpression cometNamePattern("^(.+)[(](.+)[)]\\s*$");
        QRegularExpressionMatch matchCometName = cometNamePattern.match(englishName);
        if (matchCometName.hasMatch())
                nameI18 = QString("%1(%2)").arg(matchCometName.captured(1),translator.qtranslate(matchCometName.captured(2), "comet"));
        else
                nameI18 = translator.qtranslate(englishName, "comet");
}

QString Comet::getInfoStringName(const StelCore *core, const InfoStringGroup& flags) const
{
        Q_UNUSED(core) Q_UNUSED(flags)
        QString str;
        QTextStream oss(&str);

        oss << "<h2>";
        oss << getNameI18n(); // UI translation can differ from sky translation

        if (!iauDesignation.isEmpty() &&  !getNameI18n().contains(iauDesignation))
                oss << QString(" - %1").arg(iauDesignation);

        if (!getExtraDesignations().isEmpty())
                oss << QString(" - %1").arg(extraDesignationsHtml.join(" - "));

        if (sphereScale != 1.)
        {
                oss.setRealNumberNotation(QTextStream::FixedNotation);
                oss.setRealNumberPrecision(1);
                oss << QString::fromUtf8(" (\xC3\x97") << sphereScale << ")";
        }
        oss << "</h2>";

        return str;
}

QString Comet::getInfoStringAbsoluteMagnitude(const StelCore *core, const InfoStringGroup& flags) const
{
        Q_UNUSED(core)
        QString str;
        QTextStream oss(&str);
        if (flags&AbsoluteMagnitude)
        {
                //TODO: Make sure absolute magnitude is a sane value
                //If the two parameter magnitude system is not used, don't display this
                //value. (Using radius/albedo doesn't make any sense for comets.)
                // Note that slope parameter can be <0 (down to -2?), so -10 is now used for "uninitialized"
                if (slopeParameter >= -9.9f)
                        oss << QString("%1: %2<br/>").arg(q_("Absolute Magnitude")).arg(absoluteMagnitude, 0, 'f', 2);
        }

        return str;
}

QString Comet::getInfoStringSize(const StelCore *core, const InfoStringGroup &flags) const
{
        // TRANSLATORS: Unit of measure for distance - kilometers
        QString km = qc_("km", "distance");
        // TRANSLATORS: Unit of measure for distance - milliones kilometers
        QString Mkm = qc_("M km", "distance");
        const bool withDecimalDegree = StelApp::getInstance().getFlagShowDecimalDegrees();
        QString str;
        QTextStream oss(&str);

        if (flags&Size)
        {
                // Given the very irregular shape, other terminology like "equatorial radius" do not make much sense.
                oss << QString("<br/>%1: %2 %3<br/>").arg(q_("Core diameter"), QString::number(AU * 2.0 * getEquatorialRadius(), 'f', 1) , qc_("km", "distance"));
        }
        if ((flags&Size) && (tailFactors[0]>0.0f))
        {
                // GZ: Add estimates for coma diameter and tail length.
                QString comaEst = q_("Coma diameter (estimate)");
                const double coma = std::floor(static_cast<double>(tailFactors[0])*AU/1000.0)*1000.0;
                const double tail = static_cast<double>(tailFactors[1])*AU;
                const double distanceKm = AU * getJ2000EquatorialPos(core).norm();
                // Try to estimate tail length in degrees.
                // TODO: Take projection effect into account!
                // The estimates here assume that the tail is seen from the side.
                QString comaDeg, tailDeg;
                if (withDecimalDegree)
                {
                        comaDeg = StelUtils::radToDecDegStr(atan(coma/distanceKm),4,false,true);
                        tailDeg = StelUtils::radToDecDegStr(atan(tail/distanceKm),4,false,true);
                }
                else
                {
                        comaDeg = StelUtils::radToDmsStr(atan(coma/distanceKm));
                        tailDeg = StelUtils::radToDmsStr(atan(tail/distanceKm));
                }
                if (coma>1e6)
                        oss << QString("%1: %2 %3 (%4)<br/>").arg(comaEst, QString::number(coma*1e-6, 'G', 3), Mkm, comaDeg);
                else
                        oss << QString("%1: %2 %3 (%4)<br/>").arg(comaEst, QString::number(coma, 'f', 0), km, comaDeg);
                oss << QString("%1: %2 %3 (%4)<br/>").arg(q_("Gas tail length (estimate)"), QString::number(tail*1e-6, 'G', 3), Mkm, tailDeg);
        }
        return str;
}

QString Comet::getInfoStringExtra(const StelCore *core, const InfoStringGroup &flags) const
{
        Q_UNUSED(core)
        QString str;
        QTextStream oss(&str);
        if (flags&Extra)
        {
                if (!discoveryDate.isEmpty())
                        oss << QString("%1: %2<br/>").arg(q_("Discovered"), getDiscoveryCircumstances());
        }
        return str;
}

QVariantMap Comet::getInfoMap(const StelCore *core) const
{
        QVariantMap map = Planet::getInfoMap(core);
        map.insert("tail-length-km", tailFactors[1]*AUf);
        map.insert("coma-diameter-km", tailFactors[0]*AUf);

        return map;
}

double Comet::getSiderealPeriod() const
{
        const double semiMajorAxis=static_cast<KeplerOrbit*>(orbitPtr)->getSemimajorAxis();
        return ((semiMajorAxis>0) ? KeplerOrbit::calculateSiderealPeriod(semiMajorAxis, 1.0) : 0.);
}


float Comet::getVMagnitude(const StelCore* core) const
{
        return getVMagnitude(core, 1.0);
}

float Comet::getVMagnitude(const StelCore* core, const double eclipseFactor) const
{
        Q_UNUSED(eclipseFactor)
        //If the two parameter system is not used,
        //use the default radius/albedo mechanism
        if (slopeParameter < -9.0f)
        {
                return Planet::getVMagnitude(core, 1.);
        }

        //Calculate distances
        Vec3d observerHeliocentricPosition;
        if (core->getCurrentPlanet()->getPlanetType()==Planet::isObserver)

                observerHeliocentricPosition = Vec3d(0.f,0.f,0.f);
        else
                observerHeliocentricPosition = core->getObserverHeliocentricEclipticPos();

        const Vec3d& cometHeliocentricPosition = getHeliocentricEclipticPos();
        const float cometSunDistance = static_cast<float>(cometHeliocentricPosition.norm());
        const float observerCometDistance = static_cast<float>((observerHeliocentricPosition - cometHeliocentricPosition).norm());

        //Calculate apparent magnitude
        //Sources: http://www.clearskyinstitute.com/xephem/help/xephem.html#mozTocId564354
        //(XEphem manual, section 7.1.2.3 "Magnitude models"), also
        //http://www.ayton.id.au/gary/Science/Astronomy/Ast_comets.htm#Comet%20facts:
        // GZ: Note that Meeus, Astr.Alg.1998 p.231, has m=absoluteMagnitude+5log10(observerCometDistance) + kappa*log10(cometSunDistance)
        // with kappa typically 5..15. MPC provides Slope parameter. So we should expect to have slopeParameter (a word only used for minor planets!) for our comets 2..6
        return absoluteMagnitude + 5.f * std::log10(observerCometDistance) + 2.5f * slopeParameter * std::log10(cometSunDistance);
}

void Comet::update(int deltaTime)
{
        Planet::update(deltaTime);

        //calculate FOV fade value, linear fade between intensityMaxFov and intensityMinFov
        const float vfov = static_cast<float>(StelApp::getInstance().getCore()->getMovementMgr()->getCurrentFov());
        intensityFovScale = qBound(0.25f,(vfov - intensityMinFov) / (intensityMaxFov - intensityMinFov),1.0f);

        // The rest deals with updating tail geometries and brightness
        StelCore* core=StelApp::getInstance().getCore();
        double dateJDE=core->getJDE();

        if (!static_cast<KeplerOrbit*>(orbitPtr)->objectDateGoodEnoughForOrbits(dateJDE)) return; // don't do anything if out of useful date range. This allows having hundreds of comet elements.

        //GZ: I think we can make deltaJDtail adaptive, depending on distance to sun! For some reason though, this leads to a crash!
        //deltaJDtail=StelCore::JD_SECOND * qBound(1.0, eclipticPos.length(), 20.0);

        if (fabs(lastJDEtail-dateJDE)>deltaJDEtail)
        {
                lastJDEtail=dateJDE;

                if (static_cast<KeplerOrbit*>(orbitPtr)->getUpdateTails()){
                        // Compute lengths and orientations from orbit object, but only if required.
                        tailFactors=getComaDiameterAndTailLengthAU();

                        // Note that we use a diameter larger than what the formula returns. A scale factor of 1.2 is ad-hoc/empirical (GZ), but may look better.
                        computeComa(1.0f*tailFactors[0]); // TBD: APPARENTLY NO SCALING? REMOVE 1.0 and note above.

                        tailActive = (tailFactors[1] > tailFactors[0]); // Inhibit tails drawing if too short. Would be nice to include geometric projection angle, but this is too costly.

                        if (tailActive)
                        {
                                float gasTailEndRadius=qMax(tailFactors[0], 0.025f*tailFactors[1]) ; // This avoids too slim gas tails for bright comets like Hale-Bopp.
                                float gasparameter=gasTailEndRadius*gasTailEndRadius/(2.0f*tailFactors[1]); // parabola formula: z=r²/2p, so p=r²/2z
                                // The dust tail is thicker and usually shorter. The factors can be configured in the elements.
                                float dustparameter=gasTailEndRadius*gasTailEndRadius*dustTailWidthFactor*dustTailWidthFactor/(2.0f*dustTailLengthFactor*tailFactors[1]);

                                // Find valid parameters to create paraboloid vertex arrays: dustTail, gasTail.
                                computeParabola(gasparameter, gasTailEndRadius, -0.5f*gasparameter, gastailVertexArr,  tailTexCoordArr, tailIndices);
                                //gastailColorArr.fill(Vec3f(0.3,0.3,0.3), gastailVertexArr.length());
                                // Now we make a skewed parabola. Skew factor (xOffset, last arg) is rather ad-hoc/empirical. TBD later: Find physically correct solution.
                                computeParabola(dustparameter, dustTailWidthFactor*gasTailEndRadius, -0.5f*dustparameter, dusttailVertexArr, tailTexCoordArr, tailIndices, 25.0f*static_cast<float>(static_cast<KeplerOrbit*>(orbitPtr)->getVelocity().norm()));
                                //dusttailColorArr.fill(Vec3f(0.3,0.3,0.3), dusttailVertexArr.length());


                                // 2014-08 for 0.13.1 Moved from drawTail() to save lots of computation per frame (There *are* folks downloading all 730 MPC current comet elements...)
                                // Find rotation matrix from 0/0/1 to eclipticPosition: crossproduct for axis (normal vector), dotproduct for angle.
                                Vec3d eclposNrm=eclipticPos+aberrationPush; eclposNrm.normalize();
                                gasTailRot=Mat4d::rotation(Vec3d(0.0, 0.0, 1.0)^(eclposNrm), std::acos(Vec3d(0.0, 0.0, 1.0).dot(eclposNrm)) );

                                Vec3d velocity=static_cast<KeplerOrbit*>(orbitPtr)->getVelocity(); // [AU/d]
                                // This was a try to rotate a straight parabola somewhat away from the antisolar direction.
                                //Mat4d dustTailRot=Mat4d::rotation(eclposNrm^(-velocity), 0.15f*std::acos(eclposNrm.dot(-velocity))); // GZ: This scale factor of 0.15 is empirical from photos of Halley and Hale-Bopp.
                                // The curved tail is curved towards positive X. We first rotate around the Z axis into a direction opposite of the motion vector, then again the antisolar rotation applies.
                                // In addition, we let the dust tail already start with a light tilt.
                                dustTailRot=gasTailRot * Mat4d::zrotation(atan2(velocity[1], velocity[0]) + M_PI) * Mat4d::yrotation(5.0*velocity.norm());

                                // Rotate vertex arrays:
                                Vec3d* gasVertices= static_cast<Vec3d*>(gastailVertexArr.data());
                                Vec3d* dustVertices=static_cast<Vec3d*>(dusttailVertexArr.data());
                                for (unsigned short int i=0; i<COMET_TAIL_SLICES*COMET_TAIL_STACKS+1; ++i)
                                {
                                        gasVertices[i].transfo4d(gasTailRot);
                                        dustVertices[i].transfo4d(dustTailRot);
                                }
                        }
                        static_cast<KeplerOrbit*>(orbitPtr)->setUpdateTails(false); // don't update until position has been recalculated elsewhere
                }
        }

        // And also update magnitude and tail brightness/extinction here.
        const bool withAtmosphere=(core->getSkyDrawer()->getFlagHasAtmosphere());

        StelToneReproducer* eye = core->getToneReproducer();
        const float lum = core->getSkyDrawer()->surfaceBrightnessToLuminance(getVMagnitude(core)+13.0f); // How to calibrate?
        // Get the luminance scaled between 0 and 1
        float aLum =eye->adaptLuminanceScaled(lum);


        // To make comet more apparent in overviews, take field of view into account:
        const float fov=core->getProjection(core->getAltAzModelViewTransform())->getFov();
        if (fov>20)
                aLum*= (fov/20.0f);

        // Now inhibit tail drawing if still too dim.
        if (aLum<0.002f)
        {
                // Far too dim: don't even show tail...
                tailBright=false;
                return;
        } else
                tailBright=true;

        // Separate factors, but avoid overly bright tails. I limit to about 0.7 for overlapping both tails which should not exceed full-white.
        float gasMagFactor=qMin(0.9f*aLum, 0.7f);
        float dustMagFactor=qMin(dustTailBrightnessFactor*aLum, 0.7f);

        // TODO: Maybe make gas color distance dependent? (various typical ingredients outgas at different temperatures...)
        Vec3f gasColor(0.15f*gasMagFactor,0.35f*gasMagFactor,0.6f*gasMagFactor); // Orig color 0.15/0.15/0.6.
        Vec3f dustColor(dustMagFactor, dustMagFactor,0.6f*dustMagFactor);

        if (withAtmosphere)
        {
                Extinction extinction=core->getSkyDrawer()->getExtinction();

                // Not only correct the color values for extinction, but for twilight conditions, also make tail end less visible.
                // I consider sky brightness over 1cd/m^2 as reason to shorten tail.
                // Below this brightness, the tail brightness loss by this method is insignificant:
                // Just counting through the vertices might make a spiral appearance. Maybe even better than stackwise? Let's see...
                static LandscapeMgr *lMgr=GETSTELMODULE(LandscapeMgr);
                const float avgAtmLum=lMgr->getAtmosphereAverageLuminance();
                const float brightnessDecreasePerVertexFromHead=1.0f/(COMET_TAIL_SLICES*COMET_TAIL_STACKS)  * avgAtmLum;
                float brightnessPerVertexFromHead=1.0f;

                gastailColorArr.clear();
                dusttailColorArr.clear();
                for (int i=0; i<gastailVertexArr.size(); ++i)
                {
                        // Gastail extinction:
                        Vec3d vertAltAz=core->j2000ToAltAz(gastailVertexArr.at(i), StelCore::RefractionOn);
                        vertAltAz.normalize();
                        Q_ASSERT(fabs(vertAltAz.normSquared()-1.0) < 0.001);
                        float oneMag=0.0f;
                        extinction.forward(vertAltAz, &oneMag);
                        float extinctionFactor=std::pow(0.4f, oneMag); // drop of one magnitude: factor 2.5 or 40%
                        gastailColorArr.append(gasColor*extinctionFactor* brightnessPerVertexFromHead*intensityFovScale);

                        // dusttail extinction:
                        vertAltAz=core->j2000ToAltAz(dusttailVertexArr.at(i), StelCore::RefractionOn);
                        vertAltAz.normalize();
                        Q_ASSERT(fabs(vertAltAz.normSquared()-1.0) < 0.001);
                        oneMag=0.0f;
                        extinction.forward(vertAltAz, &oneMag);
                        extinctionFactor=std::pow(0.4f, oneMag); // drop of one magnitude: factor 2.5 or 40%
                        dusttailColorArr.append(dustColor*extinctionFactor * brightnessPerVertexFromHead*intensityFovScale);

                        brightnessPerVertexFromHead-=brightnessDecreasePerVertexFromHead;
                }
        }
        else // no atmosphere: set all vertices to same brightness.
        {
                gastailColorArr.fill(gasColor  *intensityFovScale, gastailVertexArr.length());
                dusttailColorArr.fill(dustColor*intensityFovScale, dusttailVertexArr.length());
        }
        //qDebug() << "Comet " << getEnglishName() <<  "JDE: " << date << "gasR" << gasColor[0] << " dustR" << dustColor[0];
}


// Draw the Comet and all the related infos: name, circle etc... GZ: Taken from Planet.cpp 2013-11-05 and extended
void Comet::draw(StelCore* core, float maxMagLabels, const QFont& planetNameFont, const double eclipseFactor)
{
        Q_UNUSED(eclipseFactor)
        if (hidden)
                return;

        static SolarSystem *ss=GETSTELMODULE(SolarSystem);
        const float vMagnitude=getVMagnitude(core);

        // Exclude drawing if user set a hard limit magnitude.
        if (core->getSkyDrawer()->getFlagPlanetMagnitudeLimit() && (vMagnitude > core->getSkyDrawer()->getCustomPlanetMagnitudeLimit()))
                return;

        if (getEnglishName() == core->getCurrentLocation().planetName)
        { // Maybe even don't do that? E.g., draw tail while riding the comet? Decide later.
                return;
        }

        // This test seemed necessary for reasonable fps in case too many comet elements are loaded.
        // Problematic: Early-out here of course disables the wanted hint circles for dim comets.
        // The line makes hints for comets 5 magnitudes below sky limiting magnitude visible.
        // If comet is too faint to be seen, don't bother rendering. (Massive speedup if people have hundreds of comet elements!)
        if ((ss->getMarkerValue()==0.) && ((vMagnitude-5.0f) > core->getSkyDrawer()->getLimitMagnitude()) && !core->getCurrentLocation().planetName.contains("Observer", Qt::CaseInsensitive))
        {
                return;
        }
        if (!static_cast<KeplerOrbit*>(orbitPtr)->objectDateGoodEnoughForOrbits(core->getJDE())) return; // don't draw at all if out of useful date range. This allows having hundreds of comet elements.

        Mat4d mat = Mat4d::translation(eclipticPos+aberrationPush) * rotLocalToParent;
        // This removed totally the Planet shaking bug!!!
        StelProjector::ModelViewTranformP transfo = core->getHeliocentricEclipticModelViewTransform();
        transfo->combine(mat);

        // Compute the 2D position and check if in the screen
        const StelProjectorP prj = core->getProjection(transfo);
        const double screenRd = (getAngularRadius(core))*M_PI_180*static_cast<double>(prj->getPixelPerRadAtCenter());
        const double viewport_left = prj->getViewportPosX();
        const double viewport_bottom = prj->getViewportPosY();
        const bool projectionValid=prj->project(Vec3d(0.), screenPos);
        if (projectionValid
                && screenPos[1] > viewport_bottom - screenRd
                && screenPos[1] < viewport_bottom + prj->getViewportHeight()+screenRd
                && screenPos[0] > viewport_left - screenRd
                && screenPos[0] < viewport_left + prj->getViewportWidth() + screenRd)
        {
                // Draw the name, and the circle if it's not too close from the body it's turning around
                // this prevents name overlapping (ie for jupiter satellites)
                float ang_dist = 300.f*static_cast<float>(atan(getEclipticPos().norm()/getEquinoxEquatorialPos(core).norm())/core->getMovementMgr()->getCurrentFov());
                // if (ang_dist==0.f) ang_dist = 1.f; // if ang_dist == 0, the Planet is sun.. --> GZ: we can remove it.

                // by putting here, only draw orbit if Comet is visible for clarity
                drawOrbit(core);  // TODO - fade in here also...

                labelsFader = (flagLabels && ang_dist>0.25f && maxMagLabels>vMagnitude);

                { // encapsulate painter!
                        const StelProjectorP prjin = core->getProjection(StelCore::FrameJ2000);
                        StelPainter sPainter(prjin);
                        drawHints(core, sPainter, planetNameFont);
                        Vec3f color=Vec3f(0.25, 0.75, 1);
                        ss->drawAsteroidMarker(core, &sPainter, screenPos[0], screenPos[1], color); // This does not draw directly, but record an entry to be drawn in a batch.
                }

                draw3dModel(core,transfo,static_cast<float>(screenRd), 1.0);
        }
        else
                if (!projectionValid && prj.data()->getNameI18() == q_("Orthographic"))
                        return; // End prematurely. This excludes bad "ghost" comet tail on the wrong hemisphere in ortho projection! Maybe also Fisheye, but it's less problematic.
        else if (permanentDrawingOrbits) // A special case for demos
                        drawOrbit(core);


        // If comet is too faint to be seen, don't bother rendering. (Massive speedup if people have hundreds of comets!)
        // This test moved here so that hints are still drawn.
        if ((vMagnitude-5.0f) > core->getSkyDrawer()->getLimitMagnitude())
        {
                return;
        }

        // but tails should also be drawn if comet core is off-screen...
        if (tailActive && tailBright)
        {
                drawTail(core,transfo,true);  // gas tail
                drawTail(core,transfo,false); // dust tail
        }
        //Coma: this is just a fan disk tilted towards the observer;-)
        drawComa(core, transfo);
        return;
}

void Comet::drawTail(StelCore* core, StelProjector::ModelViewTranformP transfo, bool gas)
{        
        StelPainter sPainter(core->getProjection(transfo));
        sPainter.setBlending(true, GL_ONE, GL_ONE);

        tailTexture->bind();

        if (gas) {
                StelVertexArray vaGas(static_cast<const QVector<Vec3d> >(gastailVertexArr), StelVertexArray::Triangles,
                                      static_cast<const QVector<Vec2f> >(tailTexCoordArr), tailIndices, static_cast<const QVector<Vec3f> >(gastailColorArr));
                sPainter.drawStelVertexArray(vaGas, true);

        } else {
                StelVertexArray vaDust(static_cast<const QVector<Vec3d> >(dusttailVertexArr), StelVertexArray::Triangles,
                                      static_cast<const QVector<Vec2f> >(tailTexCoordArr), tailIndices, static_cast<const QVector<Vec3f> >(dusttailColorArr));
                sPainter.drawStelVertexArray(vaDust, true);
        }
        sPainter.setBlending(false);
}

void Comet::drawComa(StelCore* core, StelProjector::ModelViewTranformP transfo)
{
        // Find rotation matrix from 0/0/1 to viewdirection! crossproduct for axis (normal vector), dotproduct for angle.
        Vec3d eclposNrm=eclipticPos+aberrationPush - core->getObserverHeliocentricEclipticPos()  ; eclposNrm.normalize();
        Mat4d comarot=Mat4d::rotation(Vec3d(0.0, 0.0, 1.0)^(eclposNrm), std::acos(Vec3d(0.0, 0.0, 1.0).dot(eclposNrm)) );
        StelProjector::ModelViewTranformP transfo2 = transfo->clone();
        transfo2->combine(comarot);
        StelPainter sPainter(core->getProjection(transfo2));

        sPainter.setBlending(true, GL_ONE, GL_ONE);

        StelToneReproducer* eye = core->getToneReproducer();
        float lum = core->getSkyDrawer()->surfaceBrightnessToLuminance(getVMagnitudeWithExtinction(core)+11.0f); // How to calibrate?
        // Get the luminance scaled between 0 and 1
        const float aLum =eye->adaptLuminanceScaled(lum);
        const float magFactor=qBound(0.25f*intensityFovScale, aLum*intensityFovScale, 2.0f);
        comaTexture->bind();
        sPainter.setColor(0.3f*magFactor,0.7f*magFactor,magFactor);
        StelVertexArray vaComa(static_cast<const QVector<Vec3d> >(comaVertexArr), StelVertexArray::Triangles, static_cast<const QVector<Vec2f> >(comaTexCoordArr));
        sPainter.drawStelVertexArray(vaComa, true);
        sPainter.setBlending(false);
}

// Formula found at http://www.projectpluto.com/update7b.htm#comet_tail_formula
Vec2f Comet::getComaDiameterAndTailLengthAU() const
{
        const float r = static_cast<float>(getHeliocentricEclipticPos().norm());
        const float mhelio = absoluteMagnitude + slopeParameter * log10(r);
        const float Do = powf(10.0f, ((-0.0033f*mhelio - 0.07f) * mhelio + 3.25f));
        const float common = 1.0f - powf(10.0f, (-2.0f*r));
        const float D = Do * common * (1.0f - powf(10.0f, -r)) * (1000.0f*AU_KMf);
        const float Lo = powf(10.0f, ((-0.0075f*mhelio - 0.19f) * mhelio + 2.1f));
        const float L = Lo*(1.0f-powf(10.0f, -4.0f*r)) * common * (1e6f*AU_KMf);
        return Vec2f(D, L);
}

void Comet::computeComa(const float diameter)
{
        StelPainter::computeFanDisk(0.5f*diameter, 3, 3, comaVertexArr, comaTexCoordArr);
}

//! create parabola shell to represent a tail. Designed for slices=16, stacks=16, but should work with other sizes as well.
//! (Maybe slices must be an even number.)
// Parabola equation: z=x²/2p.
// xOffset for the dust tail, this may introduce a bend. Units are x per sqrt(z).
void Comet::computeParabola(const float parameter, const float radius, const float zshift,
                                                  QVector<Vec3d>& vertexArr, QVector<Vec2f>& texCoordArr,
                                                  QVector<unsigned short> &indices, const float xOffset)
{
        // keep the array and replace contents. However, using replace() is only slightly faster.
        if (vertexArr.length() < static_cast<int>(((COMET_TAIL_SLICES*COMET_TAIL_STACKS+1))))
                vertexArr.resize((COMET_TAIL_SLICES*COMET_TAIL_STACKS+1));
        if (createTailIndices) indices.clear();
        if (createTailTextureCoords) texCoordArr.clear();
        // The parabola has triangular faces with vertices on two circles that are rotated against each other. 
        float xa[2*COMET_TAIL_SLICES];
        float ya[2*COMET_TAIL_SLICES];
        float x, y, z;
        
        // fill xa, ya with sin/cosines. TBD: make more efficient with index mirroring etc.
        float da=M_PIf/COMET_TAIL_SLICES; // full circle/2slices
        for (unsigned short int i=0; i<2*COMET_TAIL_SLICES; ++i){
                xa[i]=-sin(i*da);
                ya[i]=cos(i*da);
        }
        
        vertexArr.replace(0, Vec3d(0.0, 0.0, static_cast<double>(zshift)));
        int vertexArrIndex=1;
        if (createTailTextureCoords) texCoordArr << Vec2f(0.5f, 0.5f);
        // define the indices lying on circles, starting at 1: odd rings have 1/slices+1/2slices, even-numbered rings straight 1/slices
        // inner ring#1
        for (unsigned short int ring=1; ring<=COMET_TAIL_STACKS; ++ring){
                z=ring*radius/COMET_TAIL_STACKS; z=z*z/(2*parameter) + zshift;
                const float xShift= xOffset*z*z;
                for (unsigned short int i=ring & 1; i<2*COMET_TAIL_SLICES; i+=2) { // i.e., ring1 has shifted vertices, ring2 has even ones.
                        x=xa[i]*radius*ring/COMET_TAIL_STACKS;
                        y=ya[i]*radius*ring/COMET_TAIL_STACKS;
                        vertexArr.replace(vertexArrIndex++, Vec3d(static_cast<double>(x+xShift), static_cast<double>(y), static_cast<double>(z)));
                        if (createTailTextureCoords) texCoordArr << Vec2f(0.5f+ 0.5f*x/radius, 0.5f+0.5f*y/radius);
                }
        }
        // now link the faces with indices.
        if (createTailIndices)
        {
                for (unsigned short i=1; i<COMET_TAIL_SLICES; ++i) indices << 0 << i << i+1;
                indices << 0 << COMET_TAIL_SLICES << 1; // close inner fan.
                // The other slices are a repeating pattern of 2 possibilities. Index @ring always is on the inner ring (slices-agon)
                for (unsigned short ring=1; ring<COMET_TAIL_STACKS; ring+=2) { // odd rings
                        const unsigned short int first=(ring-1)*COMET_TAIL_SLICES+1;
                        for (unsigned short int i=0; i<COMET_TAIL_SLICES-1; ++i){
                                indices << first+i << first+COMET_TAIL_SLICES+i << first+COMET_TAIL_SLICES+1+i;
                                indices << first+i << first+COMET_TAIL_SLICES+1+i << first+1+i;
                        }
                        // closing slice: mesh with other indices...
                        indices << ring*COMET_TAIL_SLICES << (ring+1)*COMET_TAIL_SLICES << ring*COMET_TAIL_SLICES+1;
                        indices << ring*COMET_TAIL_SLICES << ring*COMET_TAIL_SLICES+1 << first;
                }

                for (unsigned short int ring=2; ring<COMET_TAIL_STACKS; ring+=2) { // even rings: different sequence.
                        const unsigned short int first=(ring-1)*COMET_TAIL_SLICES+1;
                        for (unsigned short int i=0; i<COMET_TAIL_SLICES-1; ++i){
                                indices << first+i << first+COMET_TAIL_SLICES+i << first+1+i;
                                indices << first+1+i << first+COMET_TAIL_SLICES+i << first+COMET_TAIL_SLICES+1+i;
                        }
                        // closing slice: mesh with other indices...
                        indices << ring*COMET_TAIL_SLICES << (ring+1)*COMET_TAIL_SLICES << first;
                        indices << first << (ring+1)*COMET_TAIL_SLICES << ring*COMET_TAIL_SLICES+1;
                }
        }
        createTailIndices=false;
        createTailTextureCoords=false;
}

void Comet::setIAUDesignation(const QString& designation)
{
        static const QRegularExpression periodicDesignationPattern("^(\\d+)P/");
        static const QRegularExpression periodicCometPattern("^P/([\\w\\s]+)$");
        QRegularExpressionMatch matchPeriodicNumber = periodicDesignationPattern.match(englishName);
        QRegularExpressionMatch matchPeriodicComet  = periodicCometPattern.match(designation);
        if (matchPeriodicNumber.hasMatch() && matchPeriodicComet.hasMatch())
        {
                // combined designation for numbered periodic comets - 1P/1982 U1 or 146P/1984 W1
                iauDesignation = QString("%1P/%2").arg(matchPeriodicNumber.captured(1), matchPeriodicComet.captured(1));
        }
        else
                iauDesignation = designation;
}

void Comet::setExtraDesignations(QStringList codes)
{
        extraDesignations = codes;
        for (const auto& c : std::as_const(codes))
        {
                extraDesignationsHtml << renderDiscoveryDesignationHtml(c);
        }
}

QString Comet::renderDiscoveryDesignationHtml(const QString &plainTextName)
{
        static const QRegularExpression discoveryDesignationPattern("^(\\d{4}[a-z]{1})(\\d+)$");
        QRegularExpressionMatch match=discoveryDesignationPattern.match(plainTextName);
        if (match.hasMatch())
        {
                QString main = match.captured(1);
                QString suffix = match.captured(2);
                return (QString("%1<sub>%2</sub>").arg(main, suffix));
        }
        else
                return plainTextName;
}

Stellarium / stellarium / 15291801018

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