pulsaranimationwidget.cpp

/******************************************************************************
 *   Copyright (C) 2008 by Oliver Bock                                        *
 *   oliver.bock[AT]aei.mpg.de                                                *
 *                                                                            *
 *   This file is part of PulsatingScience.                                   *
 *                                                                            *
 *   PulsatingScience 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, version 3 of the License.               *
 *                                                                            *
 *   PulsatingScience 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 PulsatingScience. If not, see <http://www.gnu.org/licenses/>. *
 *                                                                            *
 ******************************************************************************/

#include "pulsaranimationwidget.h"

const double PulsarAnimationWidget::deg2rad = PI/180.0;

PulsarAnimationWidget::PulsarAnimationWidget(QWidget *parent) :
    QGLWidget(QGLFormat(QGL::AlphaChannel | QGL::SampleBuffers), parent),
    m_frameTimer(),
    m_pulseProfile(360, 0.0)
{
    QString msgThis = tr("3D animation");
    if(!format().directRendering()) {
        QString msg = tr("Sorry, no direct rendering support for %1...");
        qWarning() << msg.arg(msgThis);
    }
    if(!format().doubleBuffer()) {
        QString msg = tr("Sorry, no double buffering support for %1...");
        qWarning() << msg.arg(msgThis);
    }
    if(!format().rgba()) {
        QString msg = tr("Sorry, no RGBA support for %1...");
        qWarning() << msg.arg(msgThis);
    }
    if(!format().alpha()) {
        QString msg = tr("Sorry, no alpha channel support for %1...");
        qWarning() << msg.arg(msgThis);
    }
    if(!format().sampleBuffers()) {
        QString msg = tr("Sorry, no multisampling support for %1...");
        qWarning() << msg.arg(msgThis);
    }

    // connect primary rendering timer to local callback
    connect(&m_frameTimer, SIGNAL(timeout()), this, SLOT(updateFrame()));

    // initialize quadric pointers
    m_quadricCompanionOrbitPlane = NULL;
    m_quadricCompanion = NULL;
    m_quadricPulsarOrbitPlane = NULL;
    m_quadricPulsar = NULL;
    m_quadricPulsarCone1Shell = NULL;
    m_quadricPulsarCone2Shell = NULL;
    m_quadricPulsarSpinAxis = NULL;
    m_quadricPulsarSpinAxisTop1 = NULL;
    m_quadricPulsarSpinAxisTop2 = NULL;
    m_quadricPulsarMagneticAxis = NULL;

    // initialize texture pointers
    m_backgroundTexture = 0;
    m_beamTexture = 0;

    // initial render timing settings
    m_framesPerSecond = 25;
    m_pulsarRotationDelta = 0.0;
    m_orbitRotationDelta = 0.0;
    m_pulsarRotationAngle = 0.0;
    m_orbitRotationAngle = 0.0;

    // initial binary system parameters (have to match GUI!)
    m_pulsarMass = 1.4;
    m_pulsarRadius = 3.0;
    m_pulsarSpinAxisInclination = 0.0;
    m_pulsarMagneticAxisInclination = 60.0;
    m_pulsarSemiMajorAxis = 5.0;
    // initial spin frequency of 0.5 Hz
    m_pulsarRotationDelta = (360.0 * 0.5) / m_framesPerSecond;
    // beam properties (keep this order!)
    m_pulsarBeamLength = 3.0f;
    setPulsarBeamAngle(30);
    // initial companion is "Neutron Star"
    m_companionMass = 1.4;
    m_companionSemiMajorAxis = (m_pulsarMass/m_companionMass) * m_pulsarSemiMajorAxis;

    // update orbital period (based on settings above)
    updateOrbitPeriod();

    // initial view features
    m_showOrbits = false;
    m_showRotationAxes = false;
    m_showPulseFlashes = true;
    m_cameraInteraction = false;

    // initial view settings
    m_mouseAngleH = 0.0;
    m_mouseAngleV = 0.0;
    m_cameraZoom = 150.0;
    m_cameraZoomLBound = 10.0;
    m_cameraZoomUBound = 4500.0;
    m_mouseLastX = 0;
    m_mouseLastY = 0;

    // update camera based on settings above
    updateCameraPosition(m_mouseAngleH, m_mouseAngleV, m_cameraZoom);
}

PulsarAnimationWidget::~PulsarAnimationWidget()
{
    if(m_quadricCompanionOrbitPlane) gluDeleteQuadric(m_quadricCompanionOrbitPlane);
    if(m_quadricCompanion) gluDeleteQuadric(m_quadricCompanion);
    if(m_quadricPulsarOrbitPlane) gluDeleteQuadric(m_quadricPulsarOrbitPlane);
    if(m_quadricPulsar) gluDeleteQuadric(m_quadricPulsar);
    if(m_quadricPulsarCone1Shell) gluDeleteQuadric(m_quadricPulsarCone1Shell);
    if(m_quadricPulsarCone2Shell) gluDeleteQuadric(m_quadricPulsarCone2Shell);
    if(m_quadricPulsarSpinAxis) gluDeleteQuadric(m_quadricPulsarSpinAxis);
    if(m_quadricPulsarSpinAxisTop1) gluDeleteQuadric(m_quadricPulsarSpinAxisTop1);
    if(m_quadricPulsarSpinAxisTop2) gluDeleteQuadric(m_quadricPulsarSpinAxisTop2);
    if(m_quadricPulsarMagneticAxis) gluDeleteQuadric(m_quadricPulsarMagneticAxis);

    if(m_backgroundTexture) deleteTexture(m_backgroundTexture);
    if(m_beamTexture) deleteTexture(m_beamTexture);
}

void PulsarAnimationWidget::initializeGL()
{
    glClearColor(0.0, 0.0, 0.0, 0.0);
    glClearDepth(1.0);
    glDepthFunc(GL_LEQUAL);
    glEnable(GL_DEPTH_TEST);

    glShadeModel(GL_SMOOTH);
    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);

    GLfloat LightAmbient[] = {0.3, 0.3, 0.3, 1.0};
    GLfloat LightDiffuse[] = {1.0, 1.0, 1.0, 1.0};
    GLfloat LightSpecular[] = {1.0, 1.0, 1.0, 1.0};
    GLfloat LightPosition[] = {0.0, 0.0, 3.0, 1.0};
    GLfloat spot_direction[] = {0.0, 0.0, -1.0};

    glLightfv(GL_LIGHT0, GL_AMBIENT, LightAmbient);
    glLightfv(GL_LIGHT0, GL_DIFFUSE, LightDiffuse);
    glLightfv(GL_LIGHT0, GL_SPECULAR, LightSpecular);
    glLightfv(GL_LIGHT0, GL_POSITION, LightPosition);
    glLightf(GL_LIGHT0, GL_SPOT_CUTOFF, 50.0);
    glLightfv(GL_LIGHT0, GL_SPOT_DIRECTION, spot_direction);
    glLightf(GL_LIGHT0, GL_SPOT_EXPONENT, 10.0);

    glLightModeli(GL_LIGHT_MODEL_LOCAL_VIEWER, GL_TRUE);
    glEnable(GL_LIGHT0);

    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
    glEnable(GL_BLEND);

    m_quadricCompanionOrbitPlane = gluNewQuadric();
    m_quadricCompanion = gluNewQuadric();
    m_quadricPulsarOrbitPlane = gluNewQuadric();
    m_quadricPulsar = gluNewQuadric();
    m_quadricPulsarCone1Shell = gluNewQuadric();
    m_quadricPulsarCone2Shell = gluNewQuadric();
    m_quadricPulsarSpinAxis = gluNewQuadric();
    m_quadricPulsarSpinAxisTop1 = gluNewQuadric();
    m_quadricPulsarSpinAxisTop2 = gluNewQuadric();
    m_quadricPulsarMagneticAxis = gluNewQuadric();

    gluQuadricNormals(m_quadricCompanionOrbitPlane, GLU_SMOOTH);
    gluQuadricNormals(m_quadricCompanion, GLU_SMOOTH);
    gluQuadricNormals(m_quadricPulsarOrbitPlane, GLU_SMOOTH);
    gluQuadricNormals(m_quadricPulsar, GLU_SMOOTH);
    gluQuadricNormals(m_quadricPulsarCone1Shell, GLU_SMOOTH);
    gluQuadricNormals(m_quadricPulsarCone2Shell, GLU_SMOOTH);
    gluQuadricNormals(m_quadricPulsarSpinAxis, GLU_SMOOTH);
    gluQuadricNormals(m_quadricPulsarSpinAxisTop1, GLU_SMOOTH);
    gluQuadricNormals(m_quadricPulsarSpinAxisTop2, GLU_SMOOTH);
    gluQuadricNormals(m_quadricPulsarMagneticAxis, GLU_SMOOTH);

    // query max texture size (estimate)
    GLint maxTextureSize;
    glGetIntegerv(GL_MAX_TEXTURE_SIZE, &maxTextureSize);

    // prepare local messages
    QString msgShape = tr("%1 texture shape not quadratic!");
    QString msgPower = tr("%1 texture dimensions not a power of 2!");
    QString msgSize = tr("Maximum texture size exceeded! Scaling down %1 texture to %2x%3...");

    // prepare and check background texture
    QImage backgroundTexture(":/textures/resources/texture_background_carina.png");
    if(backgroundTexture.width() != backgroundTexture.height()) {
        qWarning() << msgShape.arg(tr("Background"));
    }
    else {
        double integer = 0.0;
        double fraction = 0.0;
        fraction = modf(log(backgroundTexture.width()) / log(2.0), &integer);
        if(fraction > 0.0) {
            qWarning() << msgPower.arg(tr("Background"));
        }
    }
    if(backgroundTexture.width() > maxTextureSize) {
        qWarning() << msgSize.arg(tr("background").arg(maxTextureSize).arg(maxTextureSize));
        backgroundTexture = backgroundTexture.scaled(maxTextureSize, maxTextureSize, Qt::IgnoreAspectRatio, Qt::SmoothTransformation);
    }

    // prepare and check beam texture
    QImage beamTexture(":/textures/resources/texture_beam.png");
    if(beamTexture.width() != beamTexture.height()) {
        qWarning() << msgShape.arg(tr("Beam"));
    }
    else {
        double integer = 0.0;
        double fraction = 0.0;
        fraction = modf(log(beamTexture.width()) / log(2.0), &integer);
        if(fraction > 0.0) {
            qWarning() << msgPower.arg(tr("Beam"));
        }
    }
    if(beamTexture.width() > maxTextureSize) {
        qWarning() << msgSize.arg(tr("beam").arg(maxTextureSize).arg(maxTextureSize));
        beamTexture = beamTexture.scaled(maxTextureSize, maxTextureSize, Qt::IgnoreAspectRatio, Qt::SmoothTransformation);
    }

    // bind textures
    m_backgroundTexture = bindTexture(backgroundTexture, GL_TEXTURE_2D, GL_RGBA);
    m_beamTexture = bindTexture(beamTexture, GL_TEXTURE_2D, GL_RGBA);

    // use mipmapped textures
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_NEAREST);
}

void PulsarAnimationWidget::resizeGL(int w, int h)
{
    glViewport(0, 0, w, h);

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();

    gluPerspective(4.5, (GLfloat)w / (GLfloat)h, 0.1, 5000.0);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
}

void PulsarAnimationWidget::paintGL()
{
    GLfloat x,y,angle;

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    // TODO: should be located elsewhere
    static GLfloat no_mat[] = {0.0, 0.0, 0.0, 1.0};
    static GLfloat mat_diffuse[] = {0.0, 0.0, 0.5, 1.0};
    static GLfloat mat_specular[] = {1.0, 1.0, 1.0, 1.0};
    static GLfloat low_shininess[] = {2.5};
    static GLfloat translucent[] = {1.0, 1.0, 1.0, 0.33};

    glMaterialfv(GL_FRONT, GL_AMBIENT, no_mat);
    glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);
    glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);
    glMaterialfv(GL_FRONT, GL_SHININESS, low_shininess);
    glMaterialfv(GL_FRONT, GL_EMISSION, no_mat);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

    gluLookAt(m_cameraPosX, m_cameraPosY, m_cameraPosZ,
              0.0, 0.0, 0.0,
              0.0, 1.0, 0.0);

    // save current state (the following is using parallel projection)
    glMatrixMode(GL_PROJECTION);
    glPushMatrix();
    {
        glLoadIdentity();
        glOrtho(0, width(), 0, height(), 0.1, 501.0);
        glMatrixMode(GL_MODELVIEW);
        glPushMatrix();
        {
            glLoadIdentity();

            // draw backdrop (independent parallel projection)
            glColor3f(0.5, 0.5, 0.5f);
            glTranslatef(0.0, 0.0, -501.0);

            // restore original state
            glMatrixMode(GL_PROJECTION);
        }
        glPopMatrix();
        glMatrixMode(GL_MODELVIEW);
    }
    glPopMatrix();

    // enable wireframe mode
    glPolygonMode(GL_FRONT_AND_BACK,GL_LINE);

    // draw earth
    glPushMatrix();
    {
        glRotatef(90, 1.0, 0.0, 0.0);

        // draw sphere, with proper lighting
        glEnable(GL_LIGHTING);
        glMaterialfv(GL_FRONT, GL_AMBIENT, no_mat);
        glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);
        gluSphere(m_quadricPulsar, m_pulsarRadius, 32, 32);
        glDisable(GL_LIGHTING);
    }
    glPopMatrix();

    // back to solid rendering
    glPolygonMode(GL_FRONT_AND_BACK,GL_FILL);

    // draw source
    glPushMatrix();
    {
        glTranslatef(3.0,
                     3.0,
                     -3.0);

        glRotatef(-30, 0.0, 1.0, 0.0);
        glRotatef(90, 1.0, 0.0, 0.0);

        glPushMatrix();
        {
            glRotatef(m_pulsarSpinAxisInclination, 1.0, 0.0, 0.0);
            glRotatef(-45, 1.0, 0.0, 0.0);

            // draw source plane normal
            glColor3f(1.0f, 0.0f, 0.0f);
            glPushMatrix();
            {
                glTranslatef(0.0, 0.0, -2.0);
                gluCylinder(m_quadricPulsarSpinAxis, 0.020, 0.020, 4.0, 32, 1);
            }
            glPopMatrix();
            glPushMatrix();
            {
                glTranslatef(0.0, 0.0, -2.0);
                gluDisk(m_quadricPulsarSpinAxisTop1, 0, 0.020, 32, 8);
            }
            glPopMatrix();
            glPushMatrix();
            {
                glTranslatef(0.0, 0.0, 2.0);
                gluDisk(m_quadricPulsarSpinAxisTop2, 0, 0.020, 32, 8);
            }
            glPopMatrix();

            glPushMatrix();
            {
                glTranslatef(0.0, 0.0, 2.0f - 0.75f);
                glBegin(GL_TRIANGLE_FAN);
                {
                    // Pinnacle of cone is shared vertex for fan, moved up z-axis
                    // to produce a cone instead of a circle
                    glVertex3f(0.0f, 0.0f, 0.75f);

                    // Loop around in a circle and specify even points along the circle
                    // as the vertices of the triangle fan (32 sections)
                    for(angle = 0.0f; angle < (2.0f*PI); angle += (PI/32.0f))
                    {
                        // Calculate x and y position of the next vertex
                        x = 0.25f * sin(angle);
                        y = 0.25f * cos(angle);

                        // Specify the next vertex for the triangle fan
                        glVertex2f(x, y);
                    }
                }
                glEnd();
            }
            glPopMatrix();

            // draw disc
            glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, translucent);
            glEnable(GL_LIGHTING);

            glPushMatrix();
            {
                gluDisk(m_quadricPulsarOrbitPlane,
                        0,
                        2,
                        64, 1);
            }
            glPopMatrix();

            glDisable(GL_LIGHTING);
        }
        glPopMatrix();
    }
    glPopMatrix();

    // save current state (the following is using parallel projection)
    glMatrixMode(GL_PROJECTION);
    glPushMatrix();
    {
        glLoadIdentity();
        glOrtho(0, width(), 0, height(), 0.1, 501.0);
        glMatrixMode(GL_MODELVIEW);
        glPushMatrix();
        {
            glLoadIdentity();

            // draw copyright info last (appears in front of everything)
            glColor4f(1.0f, 1.0f, 1.0f, 0.5f);
            QFont font;
            font.setPointSize(11);
            font.setBold(true);
            font.setFamily("Arial");
            font.setStyleStrategy((QFont::StyleStrategy) (QFont::OpenGLCompatible | QFont::PreferQuality));
            renderText(10, 25, -100, QString("Copyright %1 2017").arg(QChar(0x00A9)), font);
            renderText(10, 10, -100, tr("Max Planck Institute for Gravitational Physics"), font);

            // restore original state
            glMatrixMode(GL_PROJECTION);
        }
        glPopMatrix();
        glMatrixMode(GL_MODELVIEW);
    }
    glPopMatrix();
}

void PulsarAnimationWidget::runAnimation()
{
    m_frameTimer.start(qRound(1000.0 / m_framesPerSecond));
}

void PulsarAnimationWidget::pauseAnimation()
{
    m_frameTimer.stop();
}

void PulsarAnimationWidget::stopAnimation()
{
    m_frameTimer.stop();
    resetParameters();

    updateGL();
}

void PulsarAnimationWidget::updateFrame()
{
    m_pulsarRotationAngle += m_pulsarRotationDelta;
    if(m_pulsarRotationAngle >   360.0) {
        m_pulsarRotationAngle -= 360.0;
    }
    m_orbitRotationAngle += m_orbitRotationDelta;
    if(m_orbitRotationAngle >   360.0) {
        m_orbitRotationAngle -= 360.0;
    }

    updatePulseProfile();

    updateGL();

    emit pulsarAnimationStep(m_pulsarRotationAngle);
}

void PulsarAnimationWidget::showOrbits(bool enabled)
{
    m_showOrbits = enabled;

    updateGL();
}

void PulsarAnimationWidget::showRotationAxes(bool enabled)
{
    m_showRotationAxes = enabled;

    updateGL();
}

void PulsarAnimationWidget::showPulseFlashes(bool enabled)
{
    m_showPulseFlashes = enabled;

    updateGL();
}

void PulsarAnimationWidget::mousePressEvent(QMouseEvent *event)
{
    Q_UNUSED(event);

    m_cameraInteraction = true;
    updateGL();
}

void PulsarAnimationWidget::mouseMoveEvent(QMouseEvent *event)
{
    Qt::MouseButtons buttons = event->buttons();
    if((buttons & Qt::LeftButton) == Qt::LeftButton) {
        if(m_mouseLastX != 0) {
            m_mouseAngleH += (m_mouseLastX - event->x());
            m_mouseAngleH = m_mouseAngleH < 360 ? m_mouseAngleH : 0;
            m_mouseAngleH = m_mouseAngleH >=  0 ? m_mouseAngleH : 359;
        }
        if(m_mouseLastY != 0) {
            m_mouseAngleV -= (m_mouseLastY - event->y());
            m_mouseAngleV = m_mouseAngleV <  90 ? m_mouseAngleV : 90;
            m_mouseAngleV = m_mouseAngleV > -90 ? m_mouseAngleV : -90;
        }

        m_mouseLastX = event->x();
        m_mouseLastY = event->y();
    }
    else if((buttons & Qt::RightButton) == Qt::RightButton) {
        if(m_mouseLastY != 0) {
            m_cameraZoom -= (m_mouseLastY - event->y());
            m_cameraZoom = m_cameraZoom >= m_cameraZoomLBound ? m_cameraZoom : m_cameraZoomLBound;
            m_cameraZoom = m_cameraZoom >= m_cameraZoomUBound ? m_cameraZoomUBound : m_cameraZoom;
        }

        m_mouseLastY = event->y();
    }

    updateCameraPosition(m_mouseAngleH, m_mouseAngleV, m_cameraZoom);
}

void PulsarAnimationWidget::mouseReleaseEvent(QMouseEvent *event)
{
    Q_UNUSED(event);

    m_mouseLastX = 0;
    m_mouseLastY = 0;
    m_cameraInteraction = false;

    updateGL();
}

void PulsarAnimationWidget::showEvent(QShowEvent *event)
{
    Q_UNUSED(event);

    // update and propagate pulse profile
    updatePulseProfile();
}

void PulsarAnimationWidget::updateCameraPosition(const double angleH, const double angleV, const double zoom)
{
    m_cameraPosX = sin(angleH * deg2rad) * cos(angleV * deg2rad) * zoom;
    m_cameraPosY = sin(angleV * deg2rad) * zoom;
    m_cameraPosZ = cos(angleH * deg2rad) * cos(angleV * deg2rad) * zoom;

    updatePulseProfile();

    updateGL();
}

void PulsarAnimationWidget::setFramePerSecond(const unsigned int fps)
{
    m_framesPerSecond = fps;
}

void PulsarAnimationWidget::setPulsarSemiMajorAxis(const double length)
{
    m_pulsarSemiMajorAxis = length;
    m_companionSemiMajorAxis = (m_pulsarMass/m_companionMass) * m_pulsarSemiMajorAxis;
    updateOrbitPeriod();
    updatePulseProfile();

    updateGL();
}

void PulsarAnimationWidget::setCompanionMass(const double mass)
{
    m_companionMass = mass;
    updateOrbitRadii();
    updatePulseProfile();

    updateGL();
}

void PulsarAnimationWidget::setPulsarMass(const double mass)
{
    m_pulsarMass = mass;
    updateOrbitRadii();
    updatePulseProfile();

    updateGL();
}

void PulsarAnimationWidget::setPulsarSpinFrequency(const double frequency)
{
    m_pulsarRotationDelta = (360.0 * frequency) / m_framesPerSecond;
    updatePulseProfile();
}

void PulsarAnimationWidget::setPulsarSpinAxisInclination(const int degrees)
{
    m_pulsarSpinAxisInclination = degrees;
    updatePulseProfile();

    updateGL();
}

void PulsarAnimationWidget::setPulsarMagneticAxisInclination(const int degrees)
{
    m_pulsarMagneticAxisInclination = degrees;
    updatePulseProfile();

    updateGL();
}

void PulsarAnimationWidget::setPulsarBeamAngle(const int degrees)
{
    double beamTexturePeakCorrectionFactor = 0.83;
    double correctedOuterRadius;

    // compute visual radius
    m_pulsarBeamOuterRadius = tan(deg2rad * degrees * 0.5f) * m_pulsarBeamLength;

    // compute corrected angle for pulse profile
    correctedOuterRadius = m_pulsarBeamOuterRadius * beamTexturePeakCorrectionFactor;
    m_pulsarBeamAngle = 2 * atan(correctedOuterRadius / m_pulsarBeamLength) * 180.0/PI;

    updatePulseProfile();

    updateGL();
}

void PulsarAnimationWidget::getCameraPosition(double& cameraAngleH, double& cameraAngleV, double& cameraZoom)
{
    cameraAngleH = m_mouseAngleH;
    cameraAngleV = m_mouseAngleV;
    cameraZoom = m_cameraZoom;
}

void PulsarAnimationWidget::resetCameraPosition(const double angleH, const double angleV, const double zoom)
{
    m_mouseAngleH = angleH;
    m_mouseAngleV = angleV;
    m_cameraZoom = zoom;

    updateCameraPosition(m_mouseAngleH, m_mouseAngleV, m_cameraZoom);
}

void PulsarAnimationWidget::updateOrbitPeriod()
{
    m_orbitalPeriod = 3.1553e7 * sqrt(
                                    (pow(m_pulsarSemiMajorAxis, 3.0) * pow(m_pulsarMass+m_companionMass, 2.0)) / pow(m_companionMass, 3.0)
                                 );

    // visual correction factor (increase orbital momentum)
    double visualCorrection = 1e-8;

    m_orbitRotationDelta  = (360.0 / (m_orbitalPeriod*visualCorrection)) / m_framesPerSecond;
}

void PulsarAnimationWidget::updateOrbitRadii()
{
    m_pulsarSemiMajorAxis = 1.0015e-5 * pow(
                                            (pow(m_orbitalPeriod, 2.0) * pow(m_companionMass, 3.0)) / pow(m_pulsarMass+m_companionMass, 2.0),
                                            1.0/3.0
                                        );

    m_companionSemiMajorAxis = (m_pulsarMass/m_companionMass) * m_pulsarSemiMajorAxis;

    emit pulsarSemiMajorAxisUpdated(m_pulsarSemiMajorAxis);
}

void PulsarAnimationWidget::resetParameters()
{
    m_pulsarRotationAngle = 0.0;
    m_orbitRotationAngle = 0.0;
    updatePulseProfile();

    emit pulsarAnimationStep(m_pulsarRotationAngle);
}

void PulsarAnimationWidget::updatePulseProfile()
{
    // avoid division by zero (keep profile visible if pulsar doesn't spin)
    double pulsarRotationDelta = m_pulsarRotationDelta == 0.0 ? 0.01 : m_pulsarRotationDelta;

    // prepare parameters (e.g. convert to radians where necessary)
    const double    i               = deg2rad * m_pulsarSpinAxisInclination;
    const double    y               = deg2rad * m_pulsarMagneticAxisInclination;
    double          phiOrb          = deg2rad * (m_orbitRotationAngle + 90.0);
    const double    deltaPhiRot     = deg2rad * 1.0;
    const double    deltaPhiOrb     = deg2rad * deltaPhiRot * m_orbitRotationDelta / pulsarRotationDelta;
    const double    rp              = m_pulsarSemiMajorAxis;
    const double    xk              = -m_cameraPosZ;
    const double    yk              = -m_cameraPosX;
    const double    zk              = m_cameraPosY;
    const double    cam             = pow(xk, 2.0) + pow(yk, 2.0) + pow(zk, 2.0);
    const double    alpha           = deg2rad * (90.0 - m_mouseAngleH);
    const double    delta           = deg2rad * m_mouseAngleV;
    const double    gaussProfile    = 0.012337;

    for(int x = 0; x < 360; ++x) {
        // determine angle between pulsar's magnetic axis and line of sight
        phiOrb += deltaPhiOrb;
        const double phiRot = x * deltaPhiRot;

        double a = -sin(y) * sin(phiRot) * (xk + rp * cos(phiOrb)) \
                   + (cos(i) * sin(y) * cos(phiRot) + sin(i) * cos(y)) * (yk + rp * sin(phiOrb)) \
                   - (sin(i) * sin(y) * cos(phiRot) - cos(i) * cos(y)) * zk;

        double b = sqrt(pow(rp,2.0) + cam - (2.0 * sqrt(cam) * rp * cos(delta) * sin(alpha + phiOrb)));

        // determine and store pulse amplitude
        m_pulseProfile[x] = exp(-2.0 * (1.0 - fabs(a/b)) / gaussProfile);
    }

    // propagate new profile
    emit pulseProfileUpdated(m_pulseProfile);
}