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#include "qsgparticlesystem_p.h"
#include <qsgnode.h>
#include "qsgparticleemitter_p.h"
#include "qsgparticleaffector_p.h"
#include "qsgparticlepainter_p.h"
#include "qsgspriteengine_p.h"
#include "qsgsprite_p.h"
#include "qsgv8particledata_p.h"

#include "qsgtrailemitter_p.h"//###For auto-follow on states, perhaps should be in emitter?
#include <private/qdeclarativeengine_p.h>
#include <cmath>
#include <QDebug>

QT_BEGIN_NAMESPACE
//###Switch to define later, for now user-friendly (no compilation) debugging is worth it
DEFINE_BOOL_CONFIG_OPTION(qmlParticlesDebug, QML_PARTICLES_DEBUG)
/*!
    \qmlclass ParticleSystem QSGParticleSystem
    \inqmlmodule QtQuick.Particles 2
    \brief The ParticleSystem brings together ParticlePainter, Emitter and Affector elements.

*/

/*!
    \qmlproperty bool QtQuick.Particles2::ParticleSystem::running

    If running is set to false, the particle system will stop the simulation. All particles
    will be destroyed when the system is set to running again.

    It can also be controlled with the start() and stop() methods.
*/


/*!
    \qmlproperty bool QtQuick.Particles2::ParticleSystem::paused

    If paused is set to true, the particle system will not advance the simulation. When
    paused is set to false again, the simulation will resume from the same point it was
    paused.

    The simulation will automatically pause if it detects that there are no live particles
    left, and unpause when new live particles are added.

    It can also be controlled with the pause() and resume() methods.
*/

/*!
    \qmlproperty bool QtQuick.Particles2::ParticleSystem::clear

    clear is set to true when there are no live particles left in the system.

    You can use this to pause the system, keeping it from spending any time updating,
    but you will need to resume it in order for additional particles to be generated
    by the system.

    To kill all the particles in the system, use a Kill affector.
*/

/*!
    \qmlproperty list<Sprite> QtQuick.Particles2::ParticleSystem::particleStates

    You can define a sub-set of particle groups in this property in order to provide them
    with stochastic state transitions.

    Each QtQuick2::Sprite in this list is interpreted as corresponding to the particle group
    with ths same name. Any transitions defined in these sprites will take effect on the particle
    groups as well. Additionally TrailEmitters, Affectors and ParticlePainters definined
    inside one of these sprites are automatically associated with the corresponding particle group.
*/

/*!
    \qmlmethod void QtQuick.Particles2::ParticleSystem::pause

    Pauses the simulation if it is running.

    \sa resume, paused
*/

/*!
    \qmlmethod void QtQuick.Particles2::ParticleSystem::resume

    Resumes the simulation if it is paused.

    \sa pause, paused
*/

/*!
    \qmlmethod void QtQuick.Particles2::ParticleSystem::start

    Starts the simulation if it has not already running.

    \sa stop, restart, running
*/

/*!
    \qmlmethod void QtQuick.Particles2::ParticleSystem::stop

    Stops the simulation if it is running.

    \sa start, restart, running
*/

/*!
    \qmlmethod void QtQuick.Particles2::ParticleSystem::restart

    Stops the simulation if it is running, and then starts it.

    \sa stop, restart, running
*/
/*!
    \qmlmethod void QtQuick.Particles2::ParticleSystem::reset

    Discards all currently existing particles.

*/
const qreal EPSILON = 0.001;
//Utility functions for when within 1ms is close enough
bool timeEqualOrGreater(qreal a, qreal b){
    return (a+EPSILON >= b);
}

bool timeLess(qreal a, qreal b){
    return (a-EPSILON < b);
}

bool timeEqual(qreal a, qreal b){
    return (a+EPSILON > b) && (a-EPSILON < b);
}

int roundedTime(qreal a){// in ms
    return (int)qRound(a*1000.0);
}

QSGParticleDataHeap::QSGParticleDataHeap()
    : m_data(0)
{
    m_data.reserve(1000);
    clear();
}

void QSGParticleDataHeap::grow() //###Consider automatic growth vs resize() calls from GroupData
{
    m_data.resize(1 << ++m_size);
}

void QSGParticleDataHeap::insert(QSGParticleData* data)
{
    insertTimed(data, roundedTime(data->t + data->lifeSpan));
}

void QSGParticleDataHeap::insertTimed(QSGParticleData* data, int time){
    //TODO: Optimize 0 lifespan (or already dead) case
    if (m_lookups.contains(time)){
        m_data[m_lookups[time]].data << data;
        return;
    }
    if (m_end == (1 << m_size))
        grow();
    m_data[m_end].time = time;
    m_data[m_end].data.clear();
    m_data[m_end].data.insert(data);
    m_lookups.insert(time, m_end);
    bubbleUp(m_end++);
}

int QSGParticleDataHeap::top()
{
    if (m_end == 0)
        return 1 << 30;
    return m_data[0].time;
}

QSet<QSGParticleData*> QSGParticleDataHeap::pop()
{
    if (!m_end)
        return QSet<QSGParticleData*> ();
    QSet<QSGParticleData*> ret = m_data[0].data;
    m_lookups.remove(m_data[0].time);
    if (m_end == 1){
        --m_end;
    }else{
        m_data[0] = m_data[--m_end];
        bubbleDown(0);
    }
    return ret;
}

void QSGParticleDataHeap::clear()
{
    m_size = 0;
    m_end = 0;
    //m_size is in powers of two. So to start at 0 we have one allocated
    m_data.resize(1);
    m_lookups.clear();
}

bool QSGParticleDataHeap::contains(QSGParticleData* d)
{
    for (int i=0; i<m_end; i++)
        if (m_data[i].data.contains(d))
            return true;
    return false;
}

void QSGParticleDataHeap::swap(int a, int b)
{
    m_tmp = m_data[a];
    m_data[a] = m_data[b];
    m_data[b] = m_tmp;
    m_lookups[m_data[a].time] = a;
    m_lookups[m_data[b].time] = b;
}

void QSGParticleDataHeap::bubbleUp(int idx)//tends to be called once
{
    if (!idx)
        return;
    int parent = (idx-1)/2;
    if (m_data[idx].time < m_data[parent].time){
        swap(idx, parent);
        bubbleUp(parent);
    }
}

void QSGParticleDataHeap::bubbleDown(int idx)//tends to be called log n times
{
    int left = idx*2 + 1;
    if (left >= m_end)
        return;
    int lesser = left;
    int right = idx*2 + 2;
    if (right < m_end){
        if (m_data[left].time > m_data[right].time)
            lesser = right;
    }
    if (m_data[idx].time > m_data[lesser].time){
        swap(idx, lesser);
        bubbleDown(lesser);
    }
}

QSGParticleGroupData::QSGParticleGroupData(int id, QSGParticleSystem* sys):index(id),m_size(0),m_system(sys)
{
    initList();
}

QSGParticleGroupData::~QSGParticleGroupData()
{
    foreach (QSGParticleData* d, data)
        delete d;
}

int QSGParticleGroupData::size()
{
    return m_size;
}

QString QSGParticleGroupData::name()//### Worth caching as well?
{
    return m_system->m_groupIds.key(index);
}

void QSGParticleGroupData::setSize(int newSize){
    if (newSize == m_size)
        return;
    Q_ASSERT(newSize > m_size);//XXX allow shrinking
    data.resize(newSize);
    for (int i=m_size; i<newSize; i++){
        data[i] = new QSGParticleData(m_system);
        data[i]->group = index;
        data[i]->index = i;
        reusableIndexes << i;
    }
    int delta = newSize - m_size;
    m_size = newSize;
    foreach (QSGParticlePainter* p, painters)
        p->setCount(p->count() + delta);
}

void QSGParticleGroupData::initList()
{
    dataHeap.clear();
}

void QSGParticleGroupData::kill(QSGParticleData* d)
{
    Q_ASSERT(d->group == index);
    d->lifeSpan = 0;//Kill off
    foreach (QSGParticlePainter* p, painters)
        p->reload(d);
    reusableIndexes << d->index;
}

QSGParticleData* QSGParticleGroupData::newDatum(bool respectsLimits)
{
    //recycle();//Extra recycler round to be sure?

    while (!reusableIndexes.empty()){
        int idx = *(reusableIndexes.begin());
        reusableIndexes.remove(idx);
        if (data[idx]->stillAlive()){// ### This means resurrection of 'dead' particles. Is that allowed?
            prepareRecycler(data[idx]);
            continue;
        }
        return data[idx];
    }
    if (respectsLimits)
        return 0;

    int oldSize = m_size;
    setSize(oldSize + 10);//###+1,10%,+10? Choose something non-arbitrarily
    reusableIndexes.remove(oldSize);
    return data[oldSize];
}

bool QSGParticleGroupData::recycle()
{
    while (dataHeap.top() <= m_system->m_timeInt){
        foreach (QSGParticleData* datum, dataHeap.pop()){
            if (!datum->stillAlive()){
                reusableIndexes << datum->index;
            }else{
                prepareRecycler(datum); //ttl has been altered mid-way, put it back
            }
        }
    }

    //TODO: If the data is clear, gc (consider shrinking stack size)?
    return reusableIndexes.count() == m_size;
}

void QSGParticleGroupData::prepareRecycler(QSGParticleData* d){
    if (d->lifeSpan*1000 < m_system->maxLife){
        dataHeap.insert(d);
    } else {
        while ((roundedTime(d->t) + 2*m_system->maxLife/3) <= m_system->m_timeInt)
            d->extendLife(m_system->maxLife/3000.0);
        dataHeap.insertTimed(d, roundedTime(d->t) + 2*m_system->maxLife/3);
    }
}

QSGParticleData::QSGParticleData(QSGParticleSystem* sys)
    : group(0)
    , e(0)
    , system(sys)
    , index(0)
    , systemIndex(-1)
    , v8Datum(0)
{
    x = 0;
    y = 0;
    t = -1;
    lifeSpan = 0;
    size = 0;
    endSize = 0;
    vx = 0;
    vy = 0;
    ax = 0;
    ay = 0;
    xx = 1;
    xy = 0;
    yx = 0;
    yy = 1;
    rotation = 0;
    rotationSpeed = 0;
    autoRotate = 0;
    animIdx = 0;
    frameDuration = 1;
    frameCount = 1;
    animT = -1;
    color.r = 255;
    color.g = 255;
    color.b = 255;
    color.a = 255;
    r = 0;
    delegate = 0;
    modelIndex = -1;
}

void QSGParticleData::clone(const QSGParticleData& other)
{
    x = other.x;
    y = other.y;
    t = other.t;
    lifeSpan = other.lifeSpan;
    size = other.size;
    endSize = other.endSize;
    vx = other.vx;
    vy = other.vy;
    ax = other.ax;
    ay = other.ay;
    xx = other.xx;
    xy = other.xy;
    yx = other.yx;
    yy = other.yy;
    rotation = other.rotation;
    rotationSpeed = other.rotationSpeed;
    autoRotate = other.autoRotate;
    animIdx = other.animIdx;
    frameDuration = other.frameDuration;
    frameCount = other.frameCount;
    animT = other.animT;
    color.r = other.color.r;
    color.g = other.color.g;
    color.b = other.color.b;
    color.a = other.color.a;
    r = other.r;
    delegate = other.delegate;
    modelIndex = other.modelIndex;
}

QDeclarativeV8Handle QSGParticleData::v8Value()
{
    if (!v8Datum)
        v8Datum = new QSGV8ParticleData(QDeclarativeEnginePrivate::getV8Engine(qmlEngine(system)), this);
    return v8Datum->v8Value();
}
//sets the x accleration without affecting the instantaneous x velocity or position
void QSGParticleData::setInstantaneousAX(qreal ax)
{
    qreal t = (system->m_timeInt / 1000.0) - this->t;
    qreal vx = (this->vx + t*this->ax) - t*ax;
    qreal ex = this->x + this->vx * t + 0.5 * this->ax * t * t;
    qreal x = ex - t*vx - 0.5 * t*t*ax;

    this->ax = ax;
    this->vx = vx;
    this->x = x;
}

//sets the x velocity without affecting the instantaneous x postion
void QSGParticleData::setInstantaneousVX(qreal vx)
{
    qreal t = (system->m_timeInt / 1000.0) - this->t;
    qreal evx = vx - t*this->ax;
    qreal ex = this->x + this->vx * t + 0.5 * this->ax * t * t;
    qreal x = ex - t*evx - 0.5 * t*t*this->ax;

    this->vx = evx;
    this->x = x;
}

//sets the instantaneous x postion
void QSGParticleData::setInstantaneousX(qreal x)
{
    qreal t = (system->m_timeInt / 1000.0) - this->t;
    this->x = x - t*this->vx - 0.5 * t*t*this->ax;
}

//sets the y accleration without affecting the instantaneous y velocity or position
void QSGParticleData::setInstantaneousAY(qreal ay)
{
    qreal t = (system->m_timeInt / 1000.0) - this->t;
    qreal vy = (this->vy + t*this->ay) - t*ay;
    qreal ey = this->y + this->vy * t + 0.5 * this->ay * t * t;
    qreal y = ey - t*vy - 0.5 * t*t*ay;

    this->ay = ay;
    this->vy = vy;
    this->y = y;
}

//sets the y velocity without affecting the instantaneous y position
void QSGParticleData::setInstantaneousVY(qreal vy)
{
    qreal t = (system->m_timeInt / 1000.0) - this->t;
    qreal evy = vy - t*this->ay;
    qreal ey = this->y + this->vy * t + 0.5 * this->ay * t * t;
    qreal y = ey - t*evy - 0.5 * t*t*this->ay;

    this->vy = evy;
    this->y = y;
}

//sets the instantaneous Y position
void QSGParticleData::setInstantaneousY(qreal y)
{
    qreal t = (system->m_timeInt / 1000.0) - this->t;
    this->y = y - t*this->vy - 0.5 * t*t*this->ay;
}

qreal QSGParticleData::curX() const
{
    qreal t = (system->m_timeInt / 1000.0) - this->t;
    return this->x + this->vx * t + 0.5 * this->ax * t * t;
}

qreal QSGParticleData::curVX() const
{
    qreal t = (system->m_timeInt / 1000.0) - this->t;
    return this->vx + t*this->ax;
}

qreal QSGParticleData::curY() const
{
    qreal t = (system->m_timeInt / 1000.0) - this->t;
    return y + vy * t + 0.5 * ay * t * t;
}

qreal QSGParticleData::curVY() const
{
    qreal t = (system->m_timeInt / 1000.0) - this->t;
    return vy + t*ay;
}

void QSGParticleData::debugDump()
{
    qDebug() << "Particle" << systemIndex << group << "/" << index << stillAlive()
             << "Pos: " << x << "," << y
             //<< "Vel: " << vx << "," << sy
             //<< "Acc: " << ax << "," << ay
             << "Size: " << size << "," << endSize
             << "Time: " << t << "," <<lifeSpan << ";" << (system->m_timeInt / 1000.0) ;
}

bool QSGParticleData::stillAlive()
{
    if (!system)
        return false;
    //fprintf(stderr, "%.9lf %.9lf\n",((qreal)system->m_timeInt/1000.0), (t+lifeSpan));
    return (t + lifeSpan - EPSILON) > ((qreal)system->m_timeInt/1000.0);
}

float QSGParticleData::curSize()
{
    if (!system || !lifeSpan)
        return 0.0f;
    return size + (endSize - size) * (1 - (lifeLeft() / lifeSpan));
}

float QSGParticleData::lifeLeft()
{
    if (!system)
        return 0.0f;
    return (t + lifeSpan) - (system->m_timeInt/1000.0);
}

void QSGParticleData::extendLife(float time)
{
    qreal newX = curX();
    qreal newY = curY();
    qreal newVX = curVX();
    qreal newVY = curVY();

    t += time;
    animT += time;

    qreal elapsed = (system->m_timeInt / 1000.0) - t;
    qreal evy = newVY - elapsed*ay;
    qreal ey = newY - elapsed*evy - 0.5 * elapsed*elapsed*ay;
    qreal evx = newVX - elapsed*ax;
    qreal ex = newX - elapsed*evx - 0.5 * elapsed*elapsed*ax;

    x = ex;
    vx = evx;
    y = ey;
    vy = evy;
}

QSGParticleSystem::QSGParticleSystem(QSGItem *parent) :
    QSGItem(parent), m_particle_count(0), m_running(true), m_paused(false)
  , m_nextIndex(0), m_componentComplete(false), m_spriteEngine(0)
{
    connect(&m_painterMapper, SIGNAL(mapped(QObject*)),
            this, SLOT(loadPainter(QObject*)));

    m_debugMode = qmlParticlesDebug();
}

QSGParticleSystem::~QSGParticleSystem()
{
    foreach (QSGParticleGroupData* gd, m_groupData)
        delete gd;
}

void QSGParticleSystem::initGroups()
{
    m_reusableIndexes.clear();
    m_nextIndex = 0;

    qDeleteAll(m_groupData);
    m_groupData.clear();
    m_groupIds.clear();

    QSGParticleGroupData* gd = new QSGParticleGroupData(0, this);//Default group
    m_groupData.insert(0,gd);
    m_groupIds.insert("",0);
    m_nextGroupId = 1;
}

    QDeclarativeListProperty<QSGSprite> QSGParticleSystem::particleStates()
{
    return QDeclarativeListProperty<QSGSprite>(this, &m_states, spriteAppend, spriteCount, spriteAt, spriteClear);
}

void QSGParticleSystem::registerParticlePainter(QSGParticlePainter* p)
{
    //TODO: a way to Unregister emitters, painters and affectors
    m_painters << QPointer<QSGParticlePainter>(p);//###Set or uniqueness checking?
    connect(p, SIGNAL(particlesChanged(QStringList)),
            &m_painterMapper, SLOT(map()));
    loadPainter(p);
}

void QSGParticleSystem::registerParticleEmitter(QSGParticleEmitter* e)
{
    m_emitters << QPointer<QSGParticleEmitter>(e);//###How to get them out?
    connect(e, SIGNAL(particleCountChanged()),
            this, SLOT(emittersChanged()));
    connect(e, SIGNAL(particleChanged(QString)),
            this, SLOT(emittersChanged()));
    emittersChanged();
    e->reset();//Start, so that starttime factors appropriately
}

void QSGParticleSystem::registerParticleAffector(QSGParticleAffector* a)
{
    m_affectors << QPointer<QSGParticleAffector>(a);
}

void QSGParticleSystem::setRunning(bool arg)
{
    if (m_running != arg) {
        m_running = arg;
        emit runningChanged(arg);
        setPaused(false);
        if (m_animation)//Not created until componentCompleted
            m_running ? m_animation->start() : m_animation->stop();
        reset();
    }
}

void QSGParticleSystem::setPaused(bool arg){
    if (m_paused != arg) {
        m_paused = arg;
        if (m_animation && m_animation->state() != QAbstractAnimation::Stopped)
            m_paused ? m_animation->pause() : m_animation->resume();
        if (!m_paused){
            foreach (QSGParticlePainter *p, m_painters)
                p->update();
        }
        emit pausedChanged(arg);
    }
}

void QSGParticleSystem::stateRedirect(QDeclarativeListProperty<QObject> *prop, QObject *value)
{
    //Hooks up automatic state-associated stuff
    QSGParticleSystem* sys = qobject_cast<QSGParticleSystem*>(prop->object->parent());
    QSGSprite* sprite = qobject_cast<QSGSprite*>(prop->object);
    if (!sprite || !sys)
        return;
    QStringList list;
    list << sprite->name();
    QSGParticleAffector* a = qobject_cast<QSGParticleAffector*>(value);
    if (a){
        a->setParentItem(sys);
        a->setParticles(list);
        a->setSystem(sys);
        return;
    }
    QSGTrailEmitter* fe = qobject_cast<QSGTrailEmitter*>(value);
    if (fe){
        fe->setParentItem(sys);
        fe->setFollow(sprite->name());
        fe->setSystem(sys);
        return;
    }
    QSGParticleEmitter* e = qobject_cast<QSGParticleEmitter*>(value);
    if (e){
        e->setParentItem(sys);
        e->setParticle(sprite->name());
        e->setSystem(sys);
        return;
    }
    QSGParticlePainter* p = qobject_cast<QSGParticlePainter*>(value);
    if (p){
        p->setParentItem(sys);
        p->setParticles(list);
        p->setSystem(sys);
        return;
    }
    qWarning() << value << " was placed inside a particle system state but cannot be taken into the particle system. It will be lost.";
}

void QSGParticleSystem::componentComplete()

{
    QSGItem::componentComplete();
    m_componentComplete = true;
    m_animation = new QSGParticleSystemAnimation(this);
    reset();//restarts animation as well
}

void QSGParticleSystem::reset()
{
    if (!m_componentComplete)
        return;

    m_timeInt = 0;
    //Clear guarded pointers which have been deleted
    int cleared = 0;
    cleared += m_emitters.removeAll(0);
    cleared += m_painters.removeAll(0);
    cleared += m_affectors.removeAll(0);

    m_bySysIdx.resize(0);
    initGroups();//Also clears all logical particles

    if (!m_running)
        return;

    foreach (QSGParticleEmitter* e, m_emitters)
        e->reset();

    emittersChanged();

    foreach (QSGParticlePainter *p, m_painters){
        loadPainter(p);
        p->reset();
    }

    //### Do affectors need reset too?

    if (m_running) {//reset restarts animation (if running)
        if ((m_animation->state() == QAbstractAnimation::Running))
            m_animation->stop();
        m_animation->start();
        if (m_paused)
            m_animation->pause();
    }
    m_initialized = true;
}


void QSGParticleSystem::loadPainter(QObject *p)
{
    if (!m_componentComplete)
        return;

    QSGParticlePainter* painter = qobject_cast<QSGParticlePainter*>(p);
    Q_ASSERT(painter);//XXX
    foreach (QSGParticleGroupData* sg, m_groupData)
        sg->painters.remove(painter);
    int particleCount = 0;
    if (painter->particles().isEmpty()){//Uses default particle
        QStringList def;
        def << "";
        painter->setParticles(def);
        particleCount += m_groupData[0]->size();
        m_groupData[0]->painters << painter;
    }else{
        foreach (const QString &group, painter->particles()){
            if (group != QLatin1String("") && !m_groupIds[group]){//new group
                int id = m_nextGroupId++;
                QSGParticleGroupData* gd = new QSGParticleGroupData(id, this);
                m_groupIds.insert(group, id);
                m_groupData.insert(id, gd);
            }
            particleCount += m_groupData[m_groupIds[group]]->size();
            m_groupData[m_groupIds[group]]->painters << painter;
        }
    }
    painter->setCount(particleCount);
    painter->update();//Initial update here
    return;
}

void QSGParticleSystem::emittersChanged()
{
    if (!m_componentComplete)
        return;

    m_emitters.removeAll(0);


    QList<int> previousSizes;
    QList<int> newSizes;
    for (int i=0; i<m_nextGroupId; i++){
        previousSizes << m_groupData[i]->size();
        newSizes << 0;
    }

    foreach (QSGParticleEmitter* e, m_emitters){//Populate groups and set sizes.
        if (!m_groupIds.contains(e->particle())
                || (!e->particle().isEmpty() && !m_groupIds[e->particle()])){//or it was accidentally inserted by a failed lookup earlier
            int id = m_nextGroupId++;
            QSGParticleGroupData* gd = new QSGParticleGroupData(id, this);
            m_groupIds.insert(e->particle(), id);
            m_groupData.insert(id, gd);
            previousSizes << 0;
            newSizes << 0;
        }
        newSizes[m_groupIds[e->particle()]] += e->particleCount();
        //###: Cull emptied groups?
    }

    //TODO: Garbage collection?
    m_particle_count = 0;
    for (int i=0; i<m_nextGroupId; i++){
        m_groupData[i]->setSize(qMax(newSizes[i], previousSizes[i]));
        m_particle_count += m_groupData[i]->size();
    }

    Q_ASSERT(m_particle_count >= m_bySysIdx.size());//XXX when GC done right
    m_bySysIdx.resize(m_particle_count);

    foreach (QSGParticlePainter *p, m_painters)
        loadPainter(p);

    if (!m_states.isEmpty())
        createEngine();

    if (m_debugMode)
        qDebug() << "Particle system emitters changed. New particle count: " << m_particle_count;
}

void QSGParticleSystem::createEngine()
{
    if (!m_componentComplete)
        return;
    //### Solve the losses if size/states go down
    foreach (QSGSprite* sprite, m_states){
        bool exists = false;
        foreach (const QString &name, m_groupIds.keys())
            if (sprite->name() == name)
                exists = true;
        if (!exists){
            int id = m_nextGroupId++;
            QSGParticleGroupData* gd = new QSGParticleGroupData(id, this);
            m_groupIds.insert(sprite->name(), id);
            m_groupData.insert(id, gd);
        }
    }

    if (m_states.count()){
        //Reorder Sprite List so as to have the same order as groups
        QList<QSGSprite*> newList;
        for (int i=0; i<m_nextGroupId; i++){
            bool exists = false;
            QString name = m_groupData[i]->name();
            foreach (QSGSprite* existing, m_states){
                if (existing->name() == name){
                    newList << existing;
                    exists = true;
                }
            }
            if (!exists){
                newList << new QSGSprite(this);
                newList.back()->setName(name);
            }
        }
        m_states = newList;

        if (!m_spriteEngine)
            m_spriteEngine = new QSGSpriteEngine(this);
        m_spriteEngine->setCount(m_particle_count);
        m_spriteEngine->m_states = m_states;

        connect(m_spriteEngine, SIGNAL(stateChanged(int)),
                this, SLOT(particleStateChange(int)));

    }else{
        if (m_spriteEngine)
            delete m_spriteEngine;
        m_spriteEngine = 0;
    }

}

void QSGParticleSystem::particleStateChange(int idx)
{
    moveGroups(m_bySysIdx[idx], m_spriteEngine->spriteState(idx));
}

void QSGParticleSystem::moveGroups(QSGParticleData *d, int newGIdx)
{
    QSGParticleData* pd = newDatum(newGIdx, false, d->systemIndex);
    pd->clone(*d);
    finishNewDatum(pd);

    d->systemIndex = -1;
    m_groupData[d->group]->kill(d);
}

int QSGParticleSystem::nextSystemIndex()
{
    if (!m_reusableIndexes.isEmpty()){
        int ret = *(m_reusableIndexes.begin());
        m_reusableIndexes.remove(ret);
        return ret;
    }
    if (m_nextIndex >= m_bySysIdx.size()){
        m_bySysIdx.resize(m_bySysIdx.size() < 10 ? 10 : m_bySysIdx.size()*1.1);//###+1,10%,+10? Choose something non-arbitrarily
        if (m_spriteEngine)
            m_spriteEngine->setCount(m_bySysIdx.size());

    }
    return m_nextIndex++;
}

QSGParticleData* QSGParticleSystem::newDatum(int groupId, bool respectLimits, int sysIndex)
{
    Q_ASSERT(groupId < m_groupData.count());//XXX shouldn't really be an assert

    QSGParticleData* ret = m_groupData[groupId]->newDatum(respectLimits);
    if (!ret){
        return 0;
    }
    if (sysIndex == -1){
        if (ret->systemIndex == -1)
            ret->systemIndex = nextSystemIndex();
    }else{
        if (ret->systemIndex != -1){
            if (m_spriteEngine)
                m_spriteEngine->stopSprite(ret->systemIndex);
            m_reusableIndexes << ret->systemIndex;
            m_bySysIdx[ret->systemIndex] = 0;
        }
        ret->systemIndex = sysIndex;
    }
    m_bySysIdx[ret->systemIndex] = ret;

    if (m_spriteEngine)
        m_spriteEngine->startSprite(ret->systemIndex, ret->group);

    m_empty = false;
    return ret;
}

void QSGParticleSystem::emitParticle(QSGParticleData* pd)
{// called from prepareNextFrame()->emitWindow - enforce?
    //Account for relative emitter position
    QPointF offset = this->mapFromItem(pd->e, QPointF(0, 0));
    if (!offset.isNull()){
        pd->x += offset.x();
        pd->y += offset.y();
    }

    finishNewDatum(pd);
}

void QSGParticleSystem::finishNewDatum(QSGParticleData *pd){
    Q_ASSERT(pd);
    m_groupData[pd->group]->prepareRecycler(pd);

    foreach (QSGParticleAffector *a, m_affectors)
        if (a && a->m_needsReset)
            a->reset(pd);
    foreach (QSGParticlePainter* p, m_groupData[pd->group]->painters)
        if (p)
            p->load(pd);
}

void QSGParticleSystem::updateCurrentTime( int currentTime )
{
    if (!m_initialized)
        return;//error in initialization

    //### Elapsed time never shrinks - may cause problems if left emitting for weeks at a time.
    qreal dt = m_timeInt / 1000.;
    m_timeInt = currentTime;
    qreal time =  m_timeInt / 1000.;
    dt = time - dt;
    m_needsReset.clear();

    bool oldClear = m_empty;
    m_empty = true;
    foreach (QSGParticleGroupData* gd, m_groupData)//Recycle all groups and see if they're out of live particles
        m_empty = gd->recycle() && m_empty;

    if (m_spriteEngine)
        m_spriteEngine->updateSprites(m_timeInt);

    foreach (QSGParticleEmitter* emitter, m_emitters)
        if (emitter)
            emitter->emitWindow(m_timeInt);
    foreach (QSGParticleAffector* a, m_affectors)
        if (a)
            a->affectSystem(dt);
    foreach (QSGParticleData* d, m_needsReset)
        foreach (QSGParticlePainter* p, m_groupData[d->group]->painters)
            if (p && d)
                p->reload(d);

    if (oldClear != m_empty)
        emptyChanged(m_empty);
}

int QSGParticleSystem::systemSync(QSGParticlePainter* p)
{
    if (!m_running)
        return 0;
    if (!m_initialized)
        return 0;//error in initialization
    p->performPendingCommits();
    return m_timeInt;
}


QT_END_NAMESPACE