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#include "qsgfollowemitter_p.h"
#include "qsgparticlepainter_p.h"//TODO: What was this for again?
#include <cmath>
QT_BEGIN_NAMESPACE

QSGFollowEmitter::QSGFollowEmitter(QSGItem *parent) :
    QSGParticleEmitter(parent)
  , m_particlesPerParticlePerSecond(0)
  , m_lastTimeStamp(0)
  , m_emitterXVariation(0)
  , m_emitterYVariation(0)
  , m_followCount(0)
  , m_emissionExtruder(0)
  , m_defaultEmissionExtruder(new QSGParticleExtruder(this))
{
    //TODO: If followed increased their size
    connect(this, SIGNAL(followChanged(QString)),
            this, SLOT(recalcParticlesPerSecond()));
    connect(this, SIGNAL(particleDurationChanged(int)),
            this, SLOT(recalcParticlesPerSecond()));
    connect(this, SIGNAL(particlesPerParticlePerSecondChanged(int)),
            this, SLOT(recalcParticlesPerSecond()));
}

void QSGFollowEmitter::recalcParticlesPerSecond(){
    if(!m_system)
        return;
    m_followCount = m_system->m_groupData[m_system->m_groupIds[m_follow]]->size;
    if(!m_followCount){
        setParticlesPerSecond(1);//XXX: Fix this horrendous hack, needed so they aren't turned off from start (causes crashes - test that when gone you don't crash with 0 PPPS)
    }else{
        setParticlesPerSecond(m_particlesPerParticlePerSecond * m_followCount);
        m_lastEmission.resize(m_followCount);
        m_lastEmission.fill(0);
    }
}

void QSGFollowEmitter::reset()
{
    m_followCount = 0;
}

void QSGFollowEmitter::emitWindow(int timeStamp)
{
    if (m_system == 0)
        return;
    if(!m_emitting && !m_burstLeft && m_burstQueue.isEmpty())
        return;
    if(m_followCount != m_system->m_groupData[m_system->m_groupIds[m_follow]]->size){
        qreal oldPPS = m_particlesPerSecond;
        recalcParticlesPerSecond();
        if(m_particlesPerSecond != oldPPS)
            return;//system may need to update
    }

    if(m_burstLeft){
        m_burstLeft -= timeStamp - m_lastTimeStamp * 1000.;
        if(m_burstLeft < 0){
            timeStamp += m_burstLeft;
            m_burstLeft = 0;
        }
    }

    qreal time = timeStamp / 1000.;
    qreal particleRatio = 1. / m_particlesPerParticlePerSecond;
    qreal pt;

    //Have to map it into this system, because particlesystem automaps it back
    QPointF offset = m_system->mapFromItem(this, QPointF(0, 0));
    qreal sizeAtEnd = m_particleEndSize >= 0 ? m_particleEndSize : m_particleSize;

    int gId = m_system->m_groupIds[m_follow];
    int gId2 = m_system->m_groupIds[m_particle];
    foreach(QSGParticleData *d, m_system->m_groupData[gId]->data){
        if(!d || !d->stillAlive())
            continue;
        pt = m_lastEmission[d->index];
        if(pt < d->t)
            pt = d->t;

        if(!effectiveExtruder()->contains(QRectF(offset.x(), offset.y(), width(), height()),QPointF(d->curX(), d->curY()))){
            m_lastEmission[d->index] = time;//jump over this time period without emitting, because it's outside
            continue;
        }
        while(pt < time || !m_burstQueue.isEmpty()){
            QSGParticleData* datum = m_system->newDatum(gId2);
            if(datum){//else, skip this emission
                datum->e = this;//###useful?

                // Particle timestamp
                datum->t = pt;
                datum->lifeSpan =
                        (m_particleDuration
                         + ((rand() % ((m_particleDurationVariation*2) + 1)) - m_particleDurationVariation))
                        / 1000.0;

                // Particle position
                // Note that burst location doesn't get used for follow emitter
                qreal followT =  pt - d->t;
                qreal followT2 = followT * followT * 0.5;
                qreal sizeOffset = d->size/2;//TODO: Current size? As an option
                //TODO: Set variations
                //Subtract offset, because PS expects this in emitter coordinates
                QRectF boundsRect(d->x - offset.x() + d->sx * followT + d->ax * followT2 - m_emitterXVariation/2,
                                  d->y - offset.y() + d->sy * followT + d->ay * followT2 - m_emitterYVariation/2,
                                  m_emitterXVariation,
                                  m_emitterYVariation);
    //            QRectF boundsRect(d->x + d->sx * followT + d->ax * followT2 + offset.x() - sizeOffset,
    //                              d->y + d->sy * followT + d->ay * followT2 + offset.y() - sizeOffset,
    //                              sizeOffset*2,
    //                              sizeOffset*2);

                QSGParticleExtruder* effectiveEmissionExtruder = m_emissionExtruder ? m_emissionExtruder : m_defaultEmissionExtruder;
                const QPointF &newPos = effectiveEmissionExtruder->extrude(boundsRect);
                datum->x = newPos.x();
                datum->y = newPos.y();

                // Particle speed
                const QPointF &speed = m_speed->sample(newPos);
                datum->sx = speed.x();
                datum->sy = speed.y();

                // Particle acceleration
                const QPointF &accel = m_acceleration->sample(newPos);
                datum->ax = accel.x();
                datum->ay = accel.y();

                // Particle size
                float sizeVariation = -m_particleSizeVariation
                        + rand() / float(RAND_MAX) * m_particleSizeVariation * 2;

                float size = qMax((qreal)0.0, m_particleSize + sizeVariation);
                float endSize = qMax((qreal)0.0, sizeAtEnd + sizeVariation);

                datum->size = size * float(m_emitting);
                datum->endSize = endSize * float(m_emitting);

                m_system->emitParticle(datum);
            }
            if(!m_burstQueue.isEmpty()){
                m_burstQueue.first().first--;
                if(m_burstQueue.first().first <= 0)
                    m_burstQueue.pop_front();
            }else{
                pt += particleRatio;
            }
        }
        m_lastEmission[d->index] = pt;
    }

    m_lastTimeStamp = time;
}
QT_END_NAMESPACE