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#include "qsggravity_p.h"
#include <cmath>
QT_BEGIN_NAMESPACE
const qreal CONV = 0.017453292520444443;
/*!
    \qmlclass Gravity QSGGravityAffector
    \inqmlmodule QtQuick.Particles 2
    \inherits Affector
    \brief The Gravity element allows you to set a constant accleration in an angle

    This element will set the acceleration of all affected particles to a vector of
    the specified magnitude in the specified angle.
*/

/*!
    \qmlproperty real QtQuick.Particles2::Gravity::acceleration

*/
/*!
    \qmlproperty real QtQuick.Particles2::Gravity::angle
*/

QSGGravityAffector::QSGGravityAffector(QSGItem *parent) :
    QSGParticleAffector(parent), m_acceleration(-10), m_angle(90), m_xAcc(0), m_yAcc(0)
{
    connect(this, SIGNAL(accelerationChanged(qreal)),
            this, SLOT(recalc()));
    connect(this, SIGNAL(angleChanged(qreal)),
            this, SLOT(recalc()));
    recalc();
}

void QSGGravityAffector::recalc()
{
    qreal theta = m_angle * CONV;
    m_xAcc = m_acceleration * cos(theta);
    m_yAcc = m_acceleration * sin(theta);
}

bool QSGGravityAffector::affectParticle(QSGParticleData *d, qreal dt)
{
    Q_UNUSED(dt);
    bool changed = false;
    if (d->ax != m_xAcc){
        d->setInstantaneousAX(m_xAcc);
        changed = true;
    }
    if (d->ay != m_yAcc){
        d->setInstantaneousAY(m_yAcc);
        changed = true;
    }
    return changed;
}
QT_END_NAMESPACE