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#include "qquickcustomparticle_p.h"
#include <QtQuick/private/qquickshadereffectmesh_p.h>
#include <QtQuick/private/qsgshadersourcebuilder_p.h>
#include <QtQml/qqmlinfo.h>
#include <cstdlib>

QT_BEGIN_NAMESPACE

static QSGGeometry::Attribute PlainParticle_Attributes[] = {
    QSGGeometry::Attribute::create(0, 2, GL_FLOAT, true),       // Position
    QSGGeometry::Attribute::create(1, 2, GL_FLOAT),             // TexCoord
    QSGGeometry::Attribute::create(2, 4, GL_FLOAT),             // Data
    QSGGeometry::Attribute::create(3, 4, GL_FLOAT),             // Vectors
    QSGGeometry::Attribute::create(4, 1, GL_FLOAT)              // r
};

static QSGGeometry::AttributeSet PlainParticle_AttributeSet =
{
    5, // Attribute Count
    (2 + 2 + 4 + 4 + 1) * sizeof(float),
    PlainParticle_Attributes
};

struct PlainVertex {
    float x;
    float y;
    float tx;
    float ty;
    float t;
    float lifeSpan;
    float size;
    float endSize;
    float vx;
    float vy;
    float ax;
    float ay;
    float r;
};

struct PlainVertices {
    PlainVertex v1;
    PlainVertex v2;
    PlainVertex v3;
    PlainVertex v4;
};

/*!
    \qmltype CustomParticle
    \instantiates QQuickCustomParticle
    \inqmlmodule QtQuick.Particles
    \inherits ParticlePainter
    \brief For specifying shaders to paint particles
    \ingroup qtquick-particles

    \note The maximum number of custom particles is limited to 16383.
*/

QQuickCustomParticle::QQuickCustomParticle(QQuickItem* parent)
    : QQuickParticlePainter(parent)
    , m_common(this, [this](int mappedId){this->propertyChanged(mappedId);})
    , m_myMetaObject(nullptr)
    , m_dirtyUniforms(true)
    , m_dirtyUniformValues(true)
    , m_dirtyTextureProviders(true)
    , m_dirtyProgram(true)
{
    setFlag(QQuickItem::ItemHasContents);
}

void QQuickCustomParticle::sceneGraphInvalidated()
{
    m_nodes.clear();
}

QQuickCustomParticle::~QQuickCustomParticle()
{
}

void QQuickCustomParticle::componentComplete()
{
    if (!m_myMetaObject)
        m_myMetaObject = metaObject();

    m_common.updateShader(this, m_myMetaObject, Key::FragmentShader);
    updateVertexShader();
    reset();
    QQuickParticlePainter::componentComplete();
}


//Trying to keep the shader conventions the same as in qsgshadereffectitem
/*!
    \qmlproperty string QtQuick.Particles::CustomParticle::fragmentShader

    This property holds the fragment shader's GLSL source code.
    The default shader expects the texture coordinate to be passed from the
    vertex shader as "varying highp vec2 qt_TexCoord0", and it samples from a
    sampler2D named "source".
*/

void QQuickCustomParticle::setFragmentShader(const QByteArray &code)
{
    if (m_common.source.sourceCode[Key::FragmentShader].constData() == code.constData())
        return;
    m_common.source.sourceCode[Key::FragmentShader] = code;
    m_dirtyProgram = true;
    if (isComponentComplete()) {
        m_common.updateShader(this, m_myMetaObject, Key::FragmentShader);
        reset();
    }
    emit fragmentShaderChanged();
}

/*!
    \qmlproperty string QtQuick.Particles::CustomParticle::vertexShader

    This property holds the vertex shader's GLSL source code.

    The default shader passes the texture coordinate along to the fragment
    shader as "varying highp vec2 qt_TexCoord0".

    To aid writing a particle vertex shader, the following GLSL code is prepended
    to your vertex shader:
    \code
        attribute highp vec2 qt_ParticlePos;
        attribute highp vec2 qt_ParticleTex;
        attribute highp vec4 qt_ParticleData; //  x = time,  y = lifeSpan, z = size,  w = endSize
        attribute highp vec4 qt_ParticleVec; // x,y = constant velocity,  z,w = acceleration
        attribute highp float qt_ParticleR;
        uniform highp mat4 qt_Matrix;
        uniform highp float qt_Timestamp;
        varying highp vec2 qt_TexCoord0;
        void defaultMain() {
            qt_TexCoord0 = qt_ParticleTex;
            highp float size = qt_ParticleData.z;
            highp float endSize = qt_ParticleData.w;
            highp float t = (qt_Timestamp - qt_ParticleData.x) / qt_ParticleData.y;
            highp float currentSize = mix(size, endSize, t * t);
            if (t < 0. || t > 1.)
                currentSize = 0.;
            highp vec2 pos = qt_ParticlePos
                           - currentSize / 2. + currentSize * qt_ParticleTex   // adjust size
                           + qt_ParticleVec.xy * t * qt_ParticleData.y         // apply velocity vector..
                           + 0.5 * qt_ParticleVec.zw * pow(t * qt_ParticleData.y, 2.);
            gl_Position = qt_Matrix * vec4(pos.x, pos.y, 0, 1);
        }
    \endcode

    defaultMain() is the same code as in the default shader, you can call this for basic
    particle functions and then add additional variables for custom effects. Note that
    the vertex shader for particles is responsible for simulating the movement of particles
    over time, the particle data itself only has the starting position and spawn time.
*/

void QQuickCustomParticle::setVertexShader(const QByteArray &code)
{
    if (m_common.source.sourceCode[Key::VertexShader].constData() == code.constData())
        return;
    m_common.source.sourceCode[Key::VertexShader] = code;

    m_dirtyProgram = true;
    if (isComponentComplete()) {
        updateVertexShader();
        reset();
    }
    emit vertexShaderChanged();
}

void QQuickCustomParticle::updateVertexShader()
{
    m_common.disconnectPropertySignals(this, Key::VertexShader);
    m_common.uniformData[Key::VertexShader].clear();
    m_common.clearSignalMappers(Key::VertexShader);
    m_common.attributes.clear();
    m_common.attributes.append("qt_ParticlePos");
    m_common.attributes.append("qt_ParticleTex");
    m_common.attributes.append("qt_ParticleData");
    m_common.attributes.append("qt_ParticleVec");
    m_common.attributes.append("qt_ParticleR");

    UniformData d;
    d.name = "qt_Matrix";
    d.specialType = UniformData::Matrix;
    m_common.uniformData[Key::VertexShader].append(d);
    m_common.signalMappers[Key::VertexShader].append(0);

    d.name = "qt_Timestamp";
    d.specialType = UniformData::None;
    m_common.uniformData[Key::VertexShader].append(d);
    m_common.signalMappers[Key::VertexShader].append(0);

    const QByteArray &code = m_common.source.sourceCode[Key::VertexShader];
    if (!code.isEmpty())
        m_common.lookThroughShaderCode(this, m_myMetaObject, Key::VertexShader, code);

    m_common.connectPropertySignals(this, m_myMetaObject, Key::VertexShader);
}

void QQuickCustomParticle::reset()
{
    QQuickParticlePainter::reset();
    update();
}

QSGNode *QQuickCustomParticle::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData *)
{
    QQuickOpenGLShaderEffectNode *rootNode = static_cast<QQuickOpenGLShaderEffectNode *>(oldNode);
    if (m_pleaseReset){
        delete rootNode;//Automatically deletes children
        rootNode = 0;
        m_nodes.clear();
        m_pleaseReset = false;
        m_dirtyProgram = true;
    }

    if (m_system && m_system->isRunning() && !m_system->isPaused()){
        rootNode = prepareNextFrame(rootNode);
        if (rootNode) {
            foreach (QSGGeometryNode* node, m_nodes)
                node->markDirty(QSGNode::DirtyGeometry);
            update();
        }
    }

    return rootNode;
}

QQuickOpenGLShaderEffectNode *QQuickCustomParticle::prepareNextFrame(QQuickOpenGLShaderEffectNode *rootNode)
{
    if (!rootNode)
        rootNode = buildCustomNodes();

    if (!rootNode)
        return 0;

    if (m_dirtyProgram) {
        const bool isES = QOpenGLContext::currentContext()->isOpenGLES();

        QQuickOpenGLShaderEffectMaterial *material = static_cast<QQuickOpenGLShaderEffectMaterial *>(rootNode->material());
        Q_ASSERT(material);

        Key s = m_common.source;
        QSGShaderSourceBuilder builder;
        if (s.sourceCode[Key::FragmentShader].isEmpty()) {
            builder.appendSourceFile(QStringLiteral(":/particles/shaders/customparticle.frag"));
            if (isES)
                builder.removeVersion();
            s.sourceCode[Key::FragmentShader] = builder.source();
            builder.clear();
        }

        builder.appendSourceFile(QStringLiteral(":/particles/shaders/customparticletemplate.vert"));
        if (isES)
            builder.removeVersion();

        if (s.sourceCode[Key::VertexShader].isEmpty())
            builder.appendSourceFile(QStringLiteral(":/particles/shaders/customparticle.vert"));
        s.sourceCode[Key::VertexShader] = builder.source() + s.sourceCode[Key::VertexShader];

        material->setProgramSource(s);
        material->attributes = m_common.attributes;
        foreach (QQuickOpenGLShaderEffectNode* node, m_nodes)
            node->markDirty(QSGNode::DirtyMaterial);

        m_dirtyProgram = false;
        m_dirtyUniforms = true;
    }

    m_lastTime = m_system->systemSync(this) / 1000.;
    if (true) //Currently this is how we update timestamp... potentially over expensive.
        buildData(rootNode);
    return rootNode;
}

QQuickOpenGLShaderEffectNode* QQuickCustomParticle::buildCustomNodes()
{
    typedef QHash<int, QQuickOpenGLShaderEffectNode*>::const_iterator NodeHashConstIt;

    if (!QOpenGLContext::currentContext())
        return 0;

    if (m_count * 4 > 0xffff) {
        // Index data is ushort.
        qmlInfo(this) << "CustomParticle: Too many particles - maximum 16383 per CustomParticle";
        return 0;
    }

    if (m_count <= 0) {
        qmlInfo(this) << "CustomParticle: Too few particles";
        return 0;
    }

    if (groups().isEmpty())
        return 0;

    QQuickOpenGLShaderEffectNode *rootNode = 0;
    QQuickOpenGLShaderEffectMaterial *material = new QQuickOpenGLShaderEffectMaterial;
    m_dirtyProgram = true;

    for (auto groupId : groupIds()) {
        int count = m_system->groupData[groupId]->size();

        QQuickOpenGLShaderEffectNode* node = new QQuickOpenGLShaderEffectNode();
        m_nodes.insert(groupId, node);

        node->setMaterial(material);

        //Create Particle Geometry
        int vCount = count * 4;
        int iCount = count * 6;
        QSGGeometry *g = new QSGGeometry(PlainParticle_AttributeSet, vCount, iCount);
        g->setDrawingMode(GL_TRIANGLES);
        node->setGeometry(g);
        node->setFlag(QSGNode::OwnsGeometry, true);
        PlainVertex *vertices = (PlainVertex *) g->vertexData();
        for (int p=0; p < count; ++p) {
            commit(groupId, p);
            vertices[0].tx = 0;
            vertices[0].ty = 0;

            vertices[1].tx = 1;
            vertices[1].ty = 0;

            vertices[2].tx = 0;
            vertices[2].ty = 1;

            vertices[3].tx = 1;
            vertices[3].ty = 1;
            vertices += 4;
        }
        quint16 *indices = g->indexDataAsUShort();
        for (int i=0; i < count; ++i) {
            int o = i * 4;
            indices[0] = o;
            indices[1] = o + 1;
            indices[2] = o + 2;
            indices[3] = o + 1;
            indices[4] = o + 3;
            indices[5] = o + 2;
            indices += 6;
        }
    }

    NodeHashConstIt it = m_nodes.cbegin();
    rootNode = it.value();
    rootNode->setFlag(QSGNode::OwnsMaterial, true);
    NodeHashConstIt cend = m_nodes.cend();
    for (++it; it != cend; ++it)
        rootNode->appendChildNode(it.value());

    return rootNode;
}

void QQuickCustomParticle::sourceDestroyed(QObject *object)
{
    m_common.sourceDestroyed(object);
}

void QQuickCustomParticle::propertyChanged(int mappedId)
{
    bool textureProviderChanged;
    m_common.propertyChanged(this, m_myMetaObject, mappedId, &textureProviderChanged);
    m_dirtyTextureProviders |= textureProviderChanged;
    m_dirtyUniformValues = true;
    update();
}


void QQuickCustomParticle::buildData(QQuickOpenGLShaderEffectNode *rootNode)
{
    if (!rootNode)
        return;
    for (int shaderType = 0; shaderType < Key::ShaderTypeCount; ++shaderType) {
        for (int i = 0; i < m_common.uniformData[shaderType].size(); ++i) {
            if (m_common.uniformData[shaderType].at(i).name == "qt_Timestamp")
                m_common.uniformData[shaderType][i].value = qVariantFromValue(m_lastTime);
        }
    }
    m_common.updateMaterial(rootNode, static_cast<QQuickOpenGLShaderEffectMaterial *>(rootNode->material()),
                            m_dirtyUniforms, true, m_dirtyTextureProviders);
    foreach (QQuickOpenGLShaderEffectNode* node, m_nodes)
        node->markDirty(QSGNode::DirtyMaterial);
    m_dirtyUniforms = m_dirtyUniformValues = m_dirtyTextureProviders = false;
}

void QQuickCustomParticle::initialize(int gIdx, int pIdx)
{
    QQuickParticleData* datum = m_system->groupData[gIdx]->data[pIdx];
    datum->r = rand()/(qreal)RAND_MAX;
}

void QQuickCustomParticle::commit(int gIdx, int pIdx)
{
    if (m_nodes[gIdx] == 0)
        return;

    QQuickParticleData* datum = m_system->groupData[gIdx]->data[pIdx];
    PlainVertices *particles = (PlainVertices *) m_nodes[gIdx]->geometry()->vertexData();
    PlainVertex *vertices = (PlainVertex *)&particles[pIdx];
    for (int i=0; i<4; ++i) {
        vertices[i].x = datum->x - m_systemOffset.x();
        vertices[i].y = datum->y - m_systemOffset.y();
        vertices[i].t = datum->t;
        vertices[i].lifeSpan = datum->lifeSpan;
        vertices[i].size = datum->size;
        vertices[i].endSize = datum->endSize;
        vertices[i].vx = datum->vx;
        vertices[i].vy = datum->vy;
        vertices[i].ax = datum->ax;
        vertices[i].ay = datum->ay;
        vertices[i].r = datum->r;
    }
}

void QQuickCustomParticle::itemChange(ItemChange change, const ItemChangeData &value)
{
    if (change == QQuickItem::ItemSceneChange)
        m_common.updateWindow(value.window);
    QQuickParticlePainter::itemChange(change, value);
}


QT_END_NAMESPACE

#include "moc_qquickcustomparticle_p.cpp"
