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#include "qsgtargeteddirection_p.h"
#include "qsgparticleemitter_p.h"
#include <cmath>
#include <QDebug>

QT_BEGIN_NAMESPACE
QSGTargetedDirection::QSGTargetedDirection(QObject *parent) :
    QSGStochasticDirection(parent)
  , m_targetX(0)
  , m_targetY(0)
  , m_targetVariation(0)
  , m_proportionalMagnitude(false)
  , m_magnitude(0)
  , m_magnitudeVariation(0)
  , m_targetItem(0)
{
}

const QPointF &QSGTargetedDirection::sample(const QPointF &from)
{
    //###This approach loses interpolating the last position of the target (like we could with the emitter) is it worthwhile?
    qreal targetX;
    qreal targetY;
    if (m_targetItem){
        QSGParticleEmitter* parentEmitter = qobject_cast<QSGParticleEmitter*>(parent());
        targetX = m_targetItem->width()/2;
        targetY = m_targetItem->height()/2;
        if (!parentEmitter){
            qWarning() << "Directed vector is not a child of the emitter. Mapping of target item coordinates may fail.";
            targetX += m_targetItem->x();
            targetY += m_targetItem->y();
        }else{
            m_ret = parentEmitter->mapFromItem(m_targetItem, QPointF(targetX, targetY));
            targetX = m_ret.x();
            targetY = m_ret.y();
        }
    }else{
        targetX = m_targetX;
        targetY = m_targetY;
    }
    targetX += 0 - from.x() - m_targetVariation + rand()/(float)RAND_MAX * m_targetVariation*2;
    targetY += 0 - from.y() - m_targetVariation + rand()/(float)RAND_MAX * m_targetVariation*2;
    qreal theta = atan2(targetY, targetX);
    qreal mag = m_magnitude + rand()/(float)RAND_MAX * m_magnitudeVariation * 2 - m_magnitudeVariation;
    if (m_proportionalMagnitude)
        mag *= sqrt(targetX * targetX + targetY * targetY);
    m_ret.setX(mag * cos(theta));
    m_ret.setY(mag * sin(theta));
    return m_ret;
}

QT_END_NAMESPACE