qquick3dparticleemitter.cpp

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// Copyright (C) 2021 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
 
#include "qquick3dparticleemitter_p.h"
#include "qquick3dparticlemodelparticle_p.h"
#include "qquick3dparticlerandomizer_p.h"
#include "qquick3dparticleutils_p.h"
#include "qquick3dparticlespritesequence_p.h"
#include "qquick3dparticlemodelblendparticle_p.h"
 
QT_BEGIN_NAMESPACE
 
QQuick3DParticleEmitter::QQuick3DParticleEmitter(QQuick3DNode *parent)
    : QQuick3DNode(parent)
{
}
 
QQuick3DParticleEmitter::~QQuick3DParticleEmitter()
{
    qDeleteAll(m_emitBursts);
    m_emitBursts.clear();
    if (m_system)
        m_system->unRegisterParticleEmitter(this);
}
 
bool QQuick3DParticleEmitter::enabled() const
{
    return m_enabled;
}
void QQuick3DParticleEmitter::setEnabled(bool enabled)
{
    if (m_enabled == enabled)
        return;
 
    if (enabled && m_system) {
        // When enabling, we need to reset the
        // previous emit time as it might be a long time ago.
        m_prevEmitTime = m_system->currentTime();
        m_prevBurstTime = m_prevEmitTime;
    }
 
    m_enabled = enabled;
    Q_EMIT enabledChanged();
}
 
QQuick3DParticleDirection *QQuick3DParticleEmitter::velocity() const
{
    return m_velocity;
}
 
void QQuick3DParticleEmitter::setVelocity(QQuick3DParticleDirection *velocity)
{
    if (m_velocity == velocity)
        return;
 
    m_velocity = velocity;
    if (m_velocity && m_system)
        m_velocity->m_system = m_system;
 
    Q_EMIT velocityChanged();
}
 
QQuick3DParticleSystem *QQuick3DParticleEmitter::system() const
{
    return m_system;
}
 
void QQuick3DParticleEmitter::setSystem(QQuick3DParticleSystem *system)
{
    if (m_system == system)
        return;
 
    if (m_system)
        m_system->unRegisterParticleEmitter(this);
 
    m_system = system;
    if (m_system) {
        m_system->registerParticleEmitter(this);
        // Reset prev emit time to time of the new system
        m_prevEmitTime = m_system->currentTime();
        m_prevBurstTime = m_prevEmitTime;
    }
 
    if (m_particle)
        m_particle->setSystem(m_system);
 
    if (m_shape)
        m_shape->m_system = m_system;
 
    if (m_velocity)
        m_velocity->m_system = m_system;
 
    m_systemSharedParent = getSharedParentNode(this, m_system);
 
    Q_EMIT systemChanged();
}
 
float QQuick3DParticleEmitter::emitRate() const
{
    return m_emitRate;
}
 
void QQuick3DParticleEmitter::setEmitRate(float emitRate)
{
    if (qFuzzyCompare(m_emitRate, emitRate))
        return;
 
    if (m_emitRate == 0 && m_system) {
        // When changing emit rate from 0 we need to reset
        // previous emit time as it may be long time ago
        m_prevEmitTime = m_system->currentTime();
    }
    m_emitRate = emitRate;
    Q_EMIT emitRateChanged();
}
 
 
float QQuick3DParticleEmitter::particleScale() const
{
    return m_particleScale;
}
 
void QQuick3DParticleEmitter::setParticleScale(float particleScale)
{
    if (qFuzzyCompare(m_particleScale, particleScale))
        return;
 
    m_particleScale = particleScale;
    Q_EMIT particleScaleChanged();
}
 
float QQuick3DParticleEmitter::particleEndScale() const
{
    return m_particleEndScale;
}
 
void QQuick3DParticleEmitter::setParticleEndScale(float particleEndScale)
{
    if (qFuzzyCompare(m_particleEndScale, particleEndScale))
        return;
 
    m_particleEndScale = particleEndScale;
    Q_EMIT particleEndScaleChanged();
}
 
float QQuick3DParticleEmitter::particleScaleVariation() const
{
    return m_particleScaleVariation;
}
 
void QQuick3DParticleEmitter::setParticleScaleVariation(float particleScaleVariation)
{
    if (qFuzzyCompare(m_particleScaleVariation, particleScaleVariation))
        return;
 
    m_particleScaleVariation = particleScaleVariation;
    Q_EMIT particleScaleVariationChanged();
}
 
float QQuick3DParticleEmitter::particleEndScaleVariation() const
{
    return m_particleEndScaleVariation;
}
 
void QQuick3DParticleEmitter::setParticleEndScaleVariation(float particleEndScaleVariation)
{
    if (qFuzzyCompare(m_particleEndScaleVariation, particleEndScaleVariation))
        return;
 
    m_particleEndScaleVariation = particleEndScaleVariation;
    Q_EMIT particleEndScaleVariationChanged();
}
 
int QQuick3DParticleEmitter::lifeSpan() const
{
    return m_lifeSpan;
}
 
void QQuick3DParticleEmitter::setLifeSpan(int lifeSpan)
{
    if (m_lifeSpan == lifeSpan)
        return;
 
    m_lifeSpan = lifeSpan;
    Q_EMIT lifeSpanChanged();
}
 
int QQuick3DParticleEmitter::lifeSpanVariation() const
{
    return m_lifeSpanVariation;
}
 
void QQuick3DParticleEmitter::setLifeSpanVariation(int lifeSpanVariation)
{
    if (m_lifeSpanVariation == lifeSpanVariation)
        return;
 
    m_lifeSpanVariation = lifeSpanVariation;
    Q_EMIT lifeSpanVariationChanged();
}
 
QQuick3DParticle *QQuick3DParticleEmitter::particle() const
{
    return m_particle;
}
 
void QQuick3DParticleEmitter::setParticle(QQuick3DParticle *particle)
{
    if (m_particle == particle)
        return;
    if (particle && particle->system() != nullptr && m_system && particle->system() != m_system) {
        qWarning("ParticleEmitter3D: Emitter and Particle must be in the same system.");
        return;
    }
 
    if (m_particle && m_system && !m_system->isShared(m_particle))
        m_particle->setSystem(nullptr);
    m_particle = particle;
    if (particle) {
        particle->setDepthBias(m_depthBias);
        particle->setSystem(system());
        QObject::connect(this, &QQuick3DParticleEmitter::depthBiasChanged, m_particle, [this]() {
            m_particle->setDepthBias(m_depthBias);
        });
    }
    Q_EMIT particleChanged();
}
 
QQuick3DParticleAbstractShape *QQuick3DParticleEmitter::shape() const
{
    return m_shape;
}
 
void QQuick3DParticleEmitter::setShape(QQuick3DParticleAbstractShape *shape)
{
    if (m_shape == shape)
        return;
 
    m_shape = shape;
    if (m_shape && m_system)
        m_shape->m_system = m_system;
    Q_EMIT shapeChanged();
}
 
QVector3D QQuick3DParticleEmitter::particleRotation() const
{
    return m_particleRotation;
}
 
void QQuick3DParticleEmitter::setParticleRotation(const QVector3D &particleRotation)
{
    if (m_particleRotation == particleRotation)
        return;
 
    m_particleRotation = particleRotation;
    Q_EMIT particleRotationChanged();
}
 
QVector3D QQuick3DParticleEmitter::particleRotationVariation() const
{
    return m_particleRotationVariation;
}
 
void QQuick3DParticleEmitter::setParticleRotationVariation(const QVector3D &particleRotationVariation)
{
    if (m_particleRotationVariation == particleRotationVariation)
        return;
 
    m_particleRotationVariation = particleRotationVariation;
    Q_EMIT particleRotationVariationChanged();
}
 
QVector3D QQuick3DParticleEmitter::particleRotationVelocity() const
{
    return m_particleRotationVelocity;
}
 
void QQuick3DParticleEmitter::setParticleRotationVelocity(const QVector3D &particleRotationVelocity)
{
    if (m_particleRotationVelocity == particleRotationVelocity)
        return;
 
    m_particleRotationVelocity = particleRotationVelocity;
    Q_EMIT particleRotationVelocityChanged();
}
 
QVector3D QQuick3DParticleEmitter::particleRotationVelocityVariation() const
{
    return m_particleRotationVelocityVariation;
}
 
void QQuick3DParticleEmitter::setParticleRotationVelocityVariation(const QVector3D &particleRotationVelocityVariation)
{
    if (m_particleRotationVelocityVariation == particleRotationVelocityVariation)
        return;
 
    m_particleRotationVelocityVariation = particleRotationVelocityVariation;
    Q_EMIT particleRotationVariationVelocityChanged();
}
 
float QQuick3DParticleEmitter::depthBias() const
{
    return m_depthBias;
}
 
void QQuick3DParticleEmitter::setDepthBias(float bias)
{
    if (qFuzzyCompare(bias, m_depthBias))
        return;
 
    m_depthBias = bias;
    emit depthBiasChanged();
}
 
// Called to reset when system stop/continue
void QQuick3DParticleEmitter::reset()
{
    m_prevEmitTime = 0;
    m_unemittedF = 0.0f;
    m_prevBurstTime = 0;
    m_burstEmitData.clear();
}
 
void QQuick3DParticleEmitter::burst(int count)
{
    burst(count, 0, QVector3D());
}
 
void QQuick3DParticleEmitter::burst(int count, int duration)
{
    burst(count, duration, QVector3D());
}
 
void QQuick3DParticleEmitter::burst(int count, int duration, const QVector3D &position)
{
    if (!m_system)
        return;
    QQuick3DParticleEmitBurstData burst;
    burst.time = m_system->currentTime();
    burst.amount = count;
    burst.duration = duration;
    burst.position = position;
    emitParticlesBurst(burst);
}
 
void QQuick3DParticleEmitter::generateEmitBursts()
{
    if (!m_system)
        return;
 
    if (!m_particle)
        return;
 
    if (m_emitBursts.isEmpty()) {
        m_burstGenerated = true;
        return;
    }
 
    // Generating burst causes all particle data reseting
    // as bursts take first particles in the list.
    m_particle->reset();
 
    // TODO: In trail emitter case centerPos should be calculated
    // taking into account each particle position at emitburst time
    QMatrix4x4 transform = calculateParticleTransform(parentNode(), m_systemSharedParent);
    QQuaternion rotation = calculateParticleRotation(parentNode(), m_systemSharedParent);
    QVector3D centerPos = position();
 
    for (auto emitBurst : std::as_const(m_emitBursts)) {
        // Ignore all dynamic bursts here
        if (qobject_cast<QQuick3DParticleDynamicBurst *>(emitBurst))
            continue;
        int emitAmount = emitBurst->amount();
        if (emitAmount <= 0)
            return;
        // Distribute start times between burst time and time+duration.
        float startTime = float(emitBurst->time() / 1000.0f);
        float timeStep = float(emitBurst->duration() / 1000.0f) / emitAmount;
        for (int i = 0; i < emitAmount; i++) {
            emitParticle(m_particle, startTime, transform, rotation, centerPos);
            startTime += timeStep;
        }
        // Increase burst index (for statically allocated particles)
        m_particle->updateBurstIndex(emitBurst->amount());
    }
    m_burstGenerated = true;
}
 
void QQuick3DParticleEmitter::registerEmitBurst(QQuick3DParticleEmitBurst* emitBurst)
{
    m_emitBursts.removeAll(emitBurst);
    m_emitBursts << emitBurst;
    m_burstGenerated = false;
}
 
void QQuick3DParticleEmitter::unRegisterEmitBurst(QQuick3DParticleEmitBurst* emitBurst)
{
    m_emitBursts.removeAll(emitBurst);
    m_burstGenerated = false;
}
 
void QQuick3DParticleEmitter::emitParticle(QQuick3DParticle *particle, float startTime, const QMatrix4x4 &transform, const QQuaternion &parentRotation, const QVector3D &centerPos, int index)
{
    if (!m_system)
        return;
    auto rand = m_system->rand();
 
    QQuick3DParticleModelBlendParticle *mbp = qobject_cast<QQuick3DParticleModelBlendParticle *>(particle);
    if (mbp && mbp->lastParticle())
        return;
 
    int particleDataIndex = index == -1 ? particle->nextCurrentIndex(this) : index;
    if (index == -1 && mbp && mbp->emitMode() == QQuick3DParticleModelBlendParticle::Random)
        particleDataIndex = mbp->randomIndex(particleDataIndex);
 
    auto d = &particle->m_particleData[particleDataIndex];
    int particleIdIndex = m_system->m_particleIdIndex++;
    if (m_system->m_particleIdIndex == INT_MAX)
        m_system->m_particleIdIndex = 0;
 
    *d = m_clearData; // Reset the data as it might be reused
    d->index = particleIdIndex;
    d->startTime = startTime;
 
    // Life time in seconds
    float lifeSpanMs = m_lifeSpanVariation / 1000.0f;
    float lifeSpanVariationMs = lifeSpanMs - 2.0f * rand->get(particleIdIndex, QPRand::LifeSpanV) * lifeSpanMs;
    d->lifetime = (m_lifeSpan / 1000.0f) + lifeSpanVariationMs;
 
    // Size
    float sVar = m_particleScaleVariation - 2.0f * rand->get(particleIdIndex, QPRand::ScaleV) * m_particleScaleVariation;
    float endScale = (m_particleEndScale < 0.0f) ? m_particleScale : m_particleEndScale;
    float sEndVar = (m_particleEndScaleVariation < 0.0f)
            ? sVar
            : m_particleEndScaleVariation - 2.0f * rand->get(particleIdIndex, QPRand::ScaleEV) * m_particleEndScaleVariation;
    d->startSize = std::max(0.0f, float(m_particleScale + sVar));
    d->endSize = std::max(0.0f, float(endScale + sEndVar));
 
    // Emiting area/shape
    if (mbp && mbp->modelBlendMode() != QQuick3DParticleModelBlendParticle::Construct) {
        // We emit from model position unless in construct mode
        d->startPosition = mbp->particleCenter(particleDataIndex);
    } else {
        // When shape is not set, default to node center point.
        QVector3D pos = centerPos;
        if (m_shape)
            pos += m_shape->getPosition(particleIdIndex);
        d->startPosition = transform.map(pos);
    }
 
    // Velocity
    if (m_velocity) {
        // Rotate velocity based on parent node rotation and emitter rotation
        d->startVelocity = parentRotation * rotation() * m_velocity->sample(*d);
    }
 
    // Rotation
    if (!m_particleRotation.isNull() || !m_particleRotationVariation.isNull()) {
        Vector3b rot;
        constexpr float step = 127.0f / 360.0f; // +/- 360-degrees as qint8 (-127..127)
        rot.x = m_particleRotation.x() * step;
        rot.y = m_particleRotation.y() * step;
        rot.z = m_particleRotation.z() * step;
        rot.x += (m_particleRotationVariation.x() - 2.0f * rand->get(particleIdIndex, QPRand::RotXV) * m_particleRotationVariation.x()) * step;
        rot.y += (m_particleRotationVariation.y() - 2.0f * rand->get(particleIdIndex, QPRand::RotYV) * m_particleRotationVariation.y()) * step;
        rot.z += (m_particleRotationVariation.z() - 2.0f * rand->get(particleIdIndex, QPRand::RotZV) * m_particleRotationVariation.z()) * step;
        d->startRotation = rot;
    }
    // Rotation velocity
    if (!m_particleRotationVelocity.isNull() || !m_particleRotationVelocityVariation.isNull()) {
        float rotVelX = m_particleRotationVelocity.x();
        float rotVelY = m_particleRotationVelocity.y();
        float rotVelZ = m_particleRotationVelocity.z();
        rotVelX += (m_particleRotationVelocityVariation.x() - 2.0f * rand->get(particleIdIndex, QPRand::RotXVV) * m_particleRotationVelocityVariation.x());
        rotVelY += (m_particleRotationVelocityVariation.y() - 2.0f * rand->get(particleIdIndex, QPRand::RotYVV) * m_particleRotationVelocityVariation.y());
        rotVelZ += (m_particleRotationVelocityVariation.z() - 2.0f * rand->get(particleIdIndex, QPRand::RotZVV) * m_particleRotationVelocityVariation.z());
        // Particle data rotations are in qint8 vec3 to save memory.
        // max value 127*127 = 16129 degrees/second
        float sign;
        sign = rotVelX < 0.0f ? -1.0f : 1.0f;
        rotVelX = std::max(-127.0f, std::min<float>(127.0f, sign * std::sqrt(abs(rotVelX))));
        sign = rotVelY < 0.0f ? -1.0f : 1.0f;
        rotVelY = std::max(-127.0f, std::min<float>(127.0f, sign * std::sqrt(abs(rotVelY))));
        sign = rotVelZ < 0.0f ? -1.0f : 1.0f;
        rotVelZ = std::max(-127.0f, std::min<float>(127.0f, sign * std::sqrt(abs(rotVelZ))));
        d->startRotationVelocity = { qint8(rotVelX), qint8(rotVelY), qint8(rotVelZ) };
    }
 
    // Colors
    QColor pc = particle->color();
    QVector4D pcv = particle->colorVariation();
    uchar r, g, b, a;
    if (particle->unifiedColorVariation()) {
        // Vary all color channels using the same random amount
        const int randVar = int(rand->get(particleIdIndex, QPRand::ColorAV) * 256);
        r = pc.red() * (1.0f - pcv.x()) + randVar * pcv.x();
        g = pc.green() * (1.0f - pcv.y()) + randVar * pcv.y();
        b = pc.blue() * (1.0f - pcv.z()) + randVar * pcv.z();
        a = pc.alpha() * (1.0f - pcv.w()) + randVar * pcv.w();
    } else {
        r = pc.red() * (1.0f - pcv.x()) + int(rand->get(particleIdIndex, QPRand::ColorRV) * 256) * pcv.x();
        g = pc.green() * (1.0f - pcv.y()) + int(rand->get(particleIdIndex, QPRand::ColorGV) * 256) * pcv.y();
        b = pc.blue() * (1.0f - pcv.z()) + int(rand->get(particleIdIndex, QPRand::ColorBV) * 256) * pcv.z();
        a = pc.alpha() * (1.0f - pcv.w()) + int(rand->get(particleIdIndex, QPRand::ColorAV) * 256) * pcv.w();
    }
    d->startColor = {r, g, b, a};
 
    // Sprite sequence animation
    if (auto sequence = particle->m_spriteSequence) {
        if (sequence->duration() > 0) {
            float animationTimeMs = float(sequence->duration()) / 1000.0f;
            float animationTimeVarMs = float(sequence->durationVariation()) / 1000.0f;
            animationTimeVarMs = animationTimeVarMs - 2.0f * rand->get(particleIdIndex, QPRand::SpriteAnimationV) * animationTimeVarMs;
            // Sequence duration to be at least 1ms
            const float MIN_DURATION = 0.001f;
            d->animationTime = std::max(MIN_DURATION, animationTimeMs + animationTimeVarMs);
        } else {
            // Duration not set, so use the lifetime of the particle
            d->animationTime = d->lifetime;
        }
    }
}
 
int QQuick3DParticleEmitter::getEmitAmountFromDynamicBursts(int triggerType)
{
    int amount = 0;
    const int currentTime = m_system->time();
    const int prevTime = m_prevBurstTime;
    // First go through dynamic bursts and see if any of them tiggers
    for (auto *burst : std::as_const(m_emitBursts)) {
        auto *burstPtr = qobject_cast<QQuick3DParticleDynamicBurst *>(burst);
        if (!burstPtr)
            continue;
        if (!burstPtr->m_enabled)
            continue;
        // Trigering on trail emitter start / end
        const bool trailTriggering = triggerType && (burstPtr->m_triggerMode) == triggerType;
        // Triggering on time for the first time
        const bool timeTriggeringStart = !triggerType && currentTime >= burstPtr->m_time && prevTime <= burstPtr->m_time;
        if (trailTriggering || timeTriggeringStart) {
            int burstAmount = burstPtr->m_amount;
            if (burstPtr->m_amountVariation > 0) {
                auto rand = m_system->rand();
                int randAmount = 2 * rand->get() * burstPtr->m_amountVariation;
                burstAmount += burstPtr->m_amountVariation - randAmount;
            }
            if (burstAmount > 0) {
                if (timeTriggeringStart && burstPtr->m_duration > 0) {
                    // Burst with duration, so generate burst data
                    BurstEmitData emitData;
                    emitData.startTime = currentTime;
                    emitData.endTime = currentTime + burstPtr->m_duration;
                    emitData.emitAmount = burstAmount;
                    emitData.prevBurstTime = prevTime;
                    m_burstEmitData << emitData;
                } else {
                    // Directly trigger the amount
                    amount += burstAmount;
                }
            }
        }
    }
    // Then go through the triggered emit bursts list
    for (int burstIndex = 0; burstIndex < m_burstEmitData.size(); ++burstIndex) {
        auto &burstData = m_burstEmitData[burstIndex];
        const int amountLeft = burstData.emitAmount - burstData.emitCounter;
        if (currentTime >= burstData.endTime) {
            // Burst time has ended, emit all rest of the particles and remove the burst
            amount += amountLeft;
            m_burstEmitData.removeAt(burstIndex);
        } else {
            // Otherwise burst correct amount depending on burst duration
            const int durationTime = currentTime - burstData.prevBurstTime;
            const int burstDurationTime = burstData.endTime - burstData.startTime;
            int burstAmount = burstData.emitAmount * (float(durationTime) / float(burstDurationTime));
            burstAmount = std::min(amountLeft, burstAmount);
            if (burstAmount > 0) {
                amount += burstAmount;
                burstData.emitCounter += burstAmount;
                burstData.prevBurstTime = currentTime;
            }
        }
    }
    // Reset the prev burst time
    m_prevBurstTime = currentTime;
    return amount;
}
 
int QQuick3DParticleEmitter::getEmitAmount()
{
    if (!m_system)
        return 0;
 
    if (!m_enabled)
        return 0;
 
    if (m_emitRate <= 0.0f)
        return 0;
 
    float timeChange = m_system->currentTime() - m_prevEmitTime;
    float emitAmountF = timeChange / (1000.0f / m_emitRate);
    int emitAmount = floorf(emitAmountF);
    // Store the partly unemitted particles
    // When emitAmount = 0, we just let the timeChange grow.
    if (emitAmount > 0) {
        m_unemittedF += (emitAmountF - emitAmount);
        // When unemitted grow to a full particle, emit it
        // This way if emit rate is 140 emitAmounts can be e.g. 2,2,3,2,2,3 etc.
        if (m_unemittedF >= 1.0f) {
            emitAmount++;
            m_unemittedF--;
        }
    }
    return emitAmount;
}
 
void QQuick3DParticleEmitter::emitParticlesBurst(const QQuick3DParticleEmitBurstData &burst)
{
    if (!m_system)
        return;
 
    if (!m_enabled)
        return;
 
    if (!m_particle)
        return;
 
    QMatrix4x4 transform = calculateParticleTransform(parentNode(), m_systemSharedParent);
    QQuaternion rotation = calculateParticleRotation(parentNode(), m_systemSharedParent);
    QVector3D centerPos = position() + burst.position;
 
    int emitAmount = std::min(burst.amount, int(m_particle->maxAmount()));
    for (int i = 0; i < emitAmount; i++) {
        // Distribute evenly between time and time+duration.
        float startTime = (burst.time / 1000.0f) + (float(1 + i) / emitAmount) * ((burst.duration) / 1000.0f);
        emitParticle(m_particle, startTime, transform, rotation, centerPos);
    }
}
 
// Called to emit set of particles
void QQuick3DParticleEmitter::emitParticles()
{
    if (!m_system)
        return;
 
    if (!m_enabled)
        return;
 
    if (!m_particle)
        return;
 
    auto *mbp = qobject_cast<QQuick3DParticleModelBlendParticle *>(m_particle);
    if (mbp && mbp->activationNode() && mbp->emitMode() == QQuick3DParticleModelBlendParticle::Activation) {
        // The particles are emitted using the activationNode instead of regular emit
        emitActivationNodeParticles(mbp);
        return;
    }
 
    const int systemTime = m_system->currentTime();
 
    if (systemTime < m_prevEmitTime) {
        // If we are goint backwards, reset previous emit time to current time.
        m_prevEmitTime = systemTime;
    } else {
        // Keep previous emitting time within max the life span.
        // This way emitting is reasonable also with big time jumps.
        const int maxLifeSpan = m_lifeSpan + m_lifeSpanVariation;
        m_prevEmitTime = std::max(m_prevEmitTime, systemTime - maxLifeSpan);
    }
 
    // If bursts have changed, generate them first in the beginning
    if (!m_burstGenerated)
       generateEmitBursts();
 
    int emitAmount = getEmitAmount() + getEmitAmountFromDynamicBursts();
 
    // With lower emitRates, let timeChange grow until at least 1 particle is emitted
    if (emitAmount < 1)
        return;
 
    QMatrix4x4 transform = calculateParticleTransform(parentNode(), m_systemSharedParent);
    QQuaternion rotation = calculateParticleRotation(parentNode(), m_systemSharedParent);
    QVector3D centerPos = position();
 
    emitAmount = std::min(emitAmount, int(m_particle->maxAmount()));
    for (int i = 0; i < emitAmount; i++) {
        // Distribute evenly between previous and current time, important especially
        // when time has jumped a lot (like a starttime).
        float startTime = (m_prevEmitTime / 1000.0f) + (float(1+i) / emitAmount) * ((systemTime - m_prevEmitTime) / 1000.0f);
        emitParticle(m_particle, startTime, transform, rotation, centerPos);
    }
 
    m_prevEmitTime = systemTime;
}
 
void QQuick3DParticleEmitter::emitActivationNodeParticles(QQuick3DParticleModelBlendParticle *particle)
{
    QMatrix4x4 matrix = particle->activationNode()->sceneTransform();
    QMatrix4x4 actTransform = sceneTransform().inverted() * matrix;
    QVector3D front = actTransform.column(2).toVector3D();
    QVector3D pos = actTransform.column(3).toVector3D();
    float d = QVector3D::dotProduct(pos, front);
 
    const int systemTime = m_system->currentTime();
 
    // Keep previous emitting time within max the life span.
    // This way emitting is reasonable also with big time jumps.
    const int maxLifeSpan = m_lifeSpan + m_lifeSpanVariation;
    m_prevEmitTime = std::max(m_prevEmitTime, systemTime - maxLifeSpan);
 
    float startTime = systemTime / 1000.0f;
 
    QMatrix4x4 transform = calculateParticleTransform(parentNode(), m_systemSharedParent);
    QQuaternion rotation = calculateParticleRotation(parentNode(), m_systemSharedParent);
    QVector3D centerPos = position();
 
    for (int i = 0; i < particle->maxAmount(); i++) {
        if (particle->m_particleData[i].startTime >= 0)
            continue;
        const QVector3D pc = particle->particleCenter(i);
        if (QVector3D::dotProduct(front, pc) - d > 0.0f)
            emitParticle(particle, startTime, transform, rotation, centerPos, i);
    }
 
    m_prevEmitTime = systemTime;
}
 
void QQuick3DParticleEmitter::componentComplete()
{
    if (!m_system && qobject_cast<QQuick3DParticleSystem *>(parentItem()))
        setSystem(qobject_cast<QQuick3DParticleSystem *>(parentItem()));
 
    // When dynamically creating emitters, start from the current time.
    if (m_system)
        m_prevEmitTime = m_system->currentTime();
 
    QQuick3DNode::componentComplete();
}
 
// EmitBursts - list handling
 
QQmlListProperty<QQuick3DParticleEmitBurst> QQuick3DParticleEmitter::emitBursts()
{
    return {this, this,
             &QQuick3DParticleEmitter::appendEmitBurst,
             &QQuick3DParticleEmitter::emitBurstCount,
             &QQuick3DParticleEmitter::emitBurst,
             &QQuick3DParticleEmitter::clearEmitBursts,
             &QQuick3DParticleEmitter::replaceEmitBurst,
             &QQuick3DParticleEmitter::removeLastEmitBurst};
}
 
void QQuick3DParticleEmitter::appendEmitBurst(QQuick3DParticleEmitBurst* n) {
    m_emitBursts.append(n);
}
 
qsizetype QQuick3DParticleEmitter::emitBurstCount() const
{
    return m_emitBursts.size();
}
 
QQuick3DParticleEmitBurst *QQuick3DParticleEmitter::emitBurst(qsizetype index) const
{
    return m_emitBursts.at(index);
}
 
void QQuick3DParticleEmitter::clearEmitBursts() {
    m_emitBursts.clear();
}
 
void QQuick3DParticleEmitter::replaceEmitBurst(qsizetype index, QQuick3DParticleEmitBurst *n)
{
    m_emitBursts[index] = n;
}
 
void QQuick3DParticleEmitter::removeLastEmitBurst()
{
    m_emitBursts.removeLast();
}
 
// EmitBursts - static
void QQuick3DParticleEmitter::appendEmitBurst(QQmlListProperty<QQuick3DParticleEmitBurst> *list, QQuick3DParticleEmitBurst *p) {
    reinterpret_cast< QQuick3DParticleEmitter *>(list->data)->appendEmitBurst(p);
}
 
void QQuick3DParticleEmitter::clearEmitBursts(QQmlListProperty<QQuick3DParticleEmitBurst> *list) {
    reinterpret_cast< QQuick3DParticleEmitter *>(list->data)->clearEmitBursts();
}
 
void QQuick3DParticleEmitter::replaceEmitBurst(QQmlListProperty<QQuick3DParticleEmitBurst> *list, qsizetype i, QQuick3DParticleEmitBurst *p)
{
    reinterpret_cast< QQuick3DParticleEmitter *>(list->data)->replaceEmitBurst(i, p);
}
 
void QQuick3DParticleEmitter::removeLastEmitBurst(QQmlListProperty<QQuick3DParticleEmitBurst> *list)
{
    reinterpret_cast< QQuick3DParticleEmitter *>(list->data)->removeLastEmitBurst();
}
 
QQuick3DParticleEmitBurst* QQuick3DParticleEmitter::emitBurst(QQmlListProperty<QQuick3DParticleEmitBurst> *list, qsizetype i) {
    return reinterpret_cast< QQuick3DParticleEmitter *>(list->data)->emitBurst(i);
}
 
qsizetype QQuick3DParticleEmitter::emitBurstCount(QQmlListProperty<QQuick3DParticleEmitBurst> *list) {
    return reinterpret_cast< QQuick3DParticleEmitter *>(list->data)->emitBurstCount();
}
 
QT_END_NAMESPACE