/****************************************************************************
**
** Copyright (C) 2014 Klaralvdalens Datakonsult AB (KDAB).
** Copyright (C) 2015 The Qt Company Ltd and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the Qt3D module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL3$
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** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
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** information use the contact form at http://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPLv3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl.html.
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** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or later as published by the Free
** Software Foundation and appearing in the file LICENSE.GPL included in
** the packaging of this file. Please review the following information to
** ensure the GNU General Public License version 2.0 requirements will be
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** $QT_END_LICENSE$
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****************************************************************************/

#include "renderer_p.h"

#include <Qt3DCore/qentity.h>


#include <Qt3DRenderer/qmaterial.h>
#include <Qt3DRenderer/qmesh.h>
#include <Qt3DRenderer/qparametermapping.h>
#include <Qt3DRenderer/qrenderpass.h>
#include <Qt3DRenderer/qshaderprogram.h>
#include <Qt3DRenderer/qtechnique.h>
#include <Qt3DRenderer/qrenderaspect.h>
#include <Qt3DRenderer/qeffect.h>

#include <Qt3DRenderer/private/renderviewjob_p.h>
#include <Qt3DRenderer/private/blendstate_p.h>
#include <Qt3DRenderer/private/cameraselectornode_p.h>
#include <Qt3DRenderer/private/framegraphvisitor_p.h>
#include <Qt3DRenderer/private/qgraphicscontext_p.h>
#include <Qt3DRenderer/private/rendercameralens_p.h>
#include <Qt3DRenderer/private/rendercommand_p.h>
#include <Qt3DRenderer/private/renderentity_p.h>
#include <Qt3DRenderer/private/renderlogging_p.h>
#include <Qt3DRenderer/private/rendermaterial_p.h>
#include <Qt3DRenderer/private/renderpassfilternode_p.h>
#include <Qt3DRenderer/private/renderqueue_p.h>
#include <Qt3DRenderer/private/rendershader_p.h>
#include <Qt3DRenderer/private/renderstate_p.h>
#include <Qt3DRenderer/private/rendertechnique_p.h>
#include <Qt3DRenderer/private/renderthread_p.h>
#include <Qt3DRenderer/private/renderview_p.h>
#include <Qt3DRenderer/private/techniquefilternode_p.h>
#include <Qt3DRenderer/private/texturedatamanager_p.h>
#include <Qt3DRenderer/private/scenemanager_p.h>
#include <Qt3DRenderer/private/viewportnode_p.h>
#include <Qt3DRenderer/private/abstractsceneparser_p.h>
#include <Qt3DRenderer/private/vsyncframeadvanceservice_p.h>
#include <Qt3DRenderer/private/buffermanager_p.h>
#include <Qt3DRenderer/private/loadbufferjob_p.h>
#include <Qt3DRenderer/private/loadgeometryjob_p.h>
#include <Qt3DRenderer/private/geometryrenderermanager_p.h>

#include <Qt3DCore/qcameralens.h>
#include <Qt3DCore/private/qaspectmanager_p.h>
#include <Qt3DCore/private/qabstractaspectjobmanager_p.h>

#include <QStack>
#include <QSurface>
#include <QElapsedTimer>
#include <QOpenGLDebugLogger>
#include <QLibraryInfo>
#include <QPluginLoader>
#include <QDir>
#include <QUrl>
#include <QOffscreenSurface>
#include <QWindow>

// For Debug purposes only
#include <QThread>

QT_BEGIN_NAMESPACE

namespace Qt3D {

namespace Render {

static void logOpenGLDebugMessage(const QOpenGLDebugMessage &debugMessage)
{
    qDebug() << "OpenGL debug message:" << debugMessage;
}

const QString SCENE_PARSERS_PATH = QStringLiteral("/sceneparsers");


/*!
    \internal

    Renderer shutdown procedure:

    Since the renderer relies on the surface and OpenGLContext to perform its cleanup,
    it is shutdown when the surface is set to Q_NULLPTR

    When the surface is set to Q_NULLPTR this will request the RenderThread to terminate
    and will prevent createRenderBinJobs from returning a set of jobs as there is nothing
    more to be rendered.

    In turn, this will call shutdown which will make the OpenGL context current one last time
    to allow cleanups requiring a call to QOpenGLContext::currentContext to execute properly.
    At the end of that function, the QGraphicsContext is set to null.

    At this point though, the QAspectThread is still running its event loop and will only stop
    a short while after.
 */

Renderer::Renderer(QRenderAspect::RenderType type)
    : m_rendererAspect(Q_NULLPTR)
    , m_graphicsContext(Q_NULLPTR)
    , m_surface(Q_NULLPTR)
    , m_cameraManager(new CameraManager())
    , m_renderNodesManager(new EntityManager())
    , m_materialManager(new MaterialManager())
    , m_worldMatrixManager(new MatrixManager())
    , m_vaoManager(new VAOManager())
    , m_shaderManager(new ShaderManager())
    , m_techniqueManager(new TechniqueManager())
    , m_effectManager(new EffectManager())
    , m_renderPassManager(new RenderPassManager())
    , m_textureManager(new TextureManager())
    , m_textureDataManager(new TextureDataManager())
    , m_layerManager(new LayerManager())
    , m_criterionManager(new CriterionManager())
    , m_frameGraphManager(new FrameGraphManager())
    , m_transformManager(new TransformManager())
    , m_renderTargetManager(new RenderTargetManager())
    , m_sceneManager(new SceneManager())
    , m_attachmentManager(new AttachmentManager())
    , m_sortCriterionManager(new SortCriterionManager())
    , m_parameterManager(new ParameterManager())
    , m_shaderDataManager(new ShaderDataManager())
    , m_uboManager(new UBOManager())
    , m_textureImageManager(new TextureImageManager())
    , m_bufferManager(new BufferManager())
    , m_attributeManager(new AttributeManager())
    , m_geometryManager(new GeometryManager())
    , m_geometryRendererManager(new GeometryRendererManager)
    , m_renderQueue(new RenderQueue())
    , m_renderThread(type == QRenderAspect::Threaded ? new RenderThread(this) : Q_NULLPTR)
    , m_vsyncFrameAdvanceService(new VSyncFrameAdvanceService())
    , m_debugLogger(Q_NULLPTR)
{
    // Set renderer as running - it will wait in the context of the
    // RenderThread for RenderViews to be submitted
    m_running.fetchAndStoreOrdered(1);
    if (m_renderThread)
        m_renderThread->waitForStart();

    loadSceneParsers();
}

Renderer::~Renderer()
{
    // Clean up the TLS allocators
    destroyAllocators();
}

void Renderer::buildDefaultTechnique()
{
    Q_ASSERT(m_graphicsContext);
    Q_ASSERT(m_graphicsContext->openGLContext());

    // TODO: Either use public API only or just go direct to the private backend API here
    m_defaultTechnique = new QTechnique;
    m_defaultTechnique->setObjectName(QStringLiteral("default-technique"));

    QShaderProgram* defaultShader = new QShaderProgram;
    QString vertexFileName;
    QString fragmentFileName;
    if (m_graphicsContext->openGLContext()->isOpenGLES()) {
        vertexFileName = QStringLiteral("qrc:/shaders/es2/diffuse.vert");
        fragmentFileName = QStringLiteral("qrc:/shaders/es2/diffuse.frag");
    } else {
        if (m_graphicsContext->openGLContext()->format().profile() == QSurfaceFormat::CoreProfile) {
            vertexFileName = QStringLiteral("qrc:/shaders/diffuse.vert");
            fragmentFileName = QStringLiteral("qrc:/shaders/diffuse.frag");
        } else {
            vertexFileName = QStringLiteral("qrc:/shaders/es2/diffuse.vert");
            fragmentFileName = QStringLiteral("qrc:/shaders/es2/diffuse.frag");
        }
    }
    defaultShader->setVertexShaderCode(QShaderProgram::loadSource(QUrl(vertexFileName)));
    defaultShader->setFragmentShaderCode(QShaderProgram::loadSource(QUrl(fragmentFileName)));
    defaultShader->setObjectName(QStringLiteral("DefaultShader"));

    QRenderPass* basicPass = new QRenderPass;
    basicPass->setShaderProgram(defaultShader);

    m_defaultRenderStateSet = new RenderStateSet;
    m_defaultRenderStateSet->addState(DepthTest::getOrCreate(GL_LESS));
    m_defaultRenderStateSet->addState(CullFace::getOrCreate(GL_BACK));
    m_defaultRenderStateSet->addState(ColorMask::getOrCreate(true, true, true, true));
    //basicPass->setStateSet(m_defaultRenderStateSet);

    m_defaultTechnique->addPass(basicPass);

    // diffuse lighting uniforms
    QParameter* lightPos = new QParameter(QStringLiteral("lightPos"), QVector4D(10.0f, 10.0f, 0.0f, 1.0f));
    m_defaultTechnique->addParameter(lightPos);
    basicPass->addBinding(new QParameterMapping(QStringLiteral("lightPos"), QStringLiteral("lightPosition"), QParameterMapping::Uniform));

    QParameter* lightIntensity = new QParameter(QStringLiteral("lightIntensity"), QVector3D(0.5f, 0.5f, 0.5f));
    m_defaultTechnique->addParameter(lightIntensity);

    QParameter* kd = new QParameter(QStringLiteral("diffuse"), QVector3D(1.0f, 0.5f, 0.0f));
    m_defaultTechnique->addParameter(kd);
    basicPass->addBinding(new QParameterMapping(QStringLiteral("diffuse"), QStringLiteral("kd"), QParameterMapping::Uniform));

    QParameter* ka = new QParameter(QStringLiteral("ambient"), QVector3D(0.2f, 0.2f, 0.2f));
    m_defaultTechnique->addParameter(ka);
    basicPass->addBinding(new QParameterMapping(QStringLiteral("ambient"), QStringLiteral("ka"), QParameterMapping::Uniform));

}

void Renderer::loadSceneParsers()
{
    QString pluginsPath = QLibraryInfo::location(QLibraryInfo::PluginsPath) + SCENE_PARSERS_PATH;
    QDir sceneParsersPluginDir(pluginsPath);

    Q_FOREACH (QString plugin, sceneParsersPluginDir.entryList(QDir::Files)) {
        QPluginLoader loader(sceneParsersPluginDir.absoluteFilePath(plugin));
        AbstractSceneParser *parser = qobject_cast<AbstractSceneParser *>(loader.instance());
        if (parser != Q_NULLPTR)
            m_sceneParsers.append(parser);
        else
            qWarning() << "Failed to load scene parser plugin " << loader.fileName();
    }
}

void Renderer::buildDefaultMaterial()
{
    m_defaultMaterial = new QMaterial();
    m_defaultMaterial->setObjectName(QStringLiteral("DefaultMaterial"));
    m_defaultMaterial->addParameter(new QParameter(QStringLiteral("lightPos"), QVector4D(10.0f, 10.0f, 0.0f, 1.0f)));
    m_defaultMaterial->addParameter(new QParameter(QStringLiteral("lightIntensity"), QVector3D(0.5f, 0.5f, 0.5f)));
    m_defaultMaterial->addParameter(new QParameter(QStringLiteral("ambient"), QVector3D(0.2f, 0.2f, 0.2f)));
    m_defaultMaterial->addParameter(new QParameter(QStringLiteral("diffuse"), QVector3D(1.0f, 0.5f, 0.0f)));

    QEffect* defEff = new QEffect;
    defEff->addTechnique(m_defaultTechnique);
    m_defaultMaterial->setEffect(defEff);

}

void Renderer::createAllocators()
{
    // Issue a set of jobs to create an allocator in TLS for each worker thread
    Q_ASSERT(m_rendererAspect);
    QAbstractAspectJobManager *jobManager = rendererAspect()->jobManager();
    Q_ASSERT(jobManager);
    jobManager->waitForPerThreadFunction(Renderer::createThreadLocalAllocator, this);
}

void Renderer::destroyAllocators()
{
    // Issue a set of jobs to destroy the allocator in TLS for each worker thread
    Q_ASSERT(m_rendererAspect);
    QAbstractAspectJobManager *jobManager = rendererAspect()->jobManager();
    Q_ASSERT(jobManager);
    jobManager->waitForPerThreadFunction(Renderer::destroyThreadLocalAllocator, this);
}

QThreadStorage<QFrameAllocator *> *Renderer::tlsAllocators()
{
    return &m_tlsAllocators;
}

/*!
 * For each worker thread we create a QFrameAllocatorQueue which contains m_cachedFrameCount + 1
 * QFrameAllocators. We need an additional QFrameAllocator otherwise we may be clearing the QFrameAllocator
 * of the frame we are currently rendering.
 */
void Renderer::createThreadLocalAllocator(void *renderer)
{
    Q_ASSERT(renderer);
    Renderer *theRenderer = static_cast<Renderer *>(renderer);
    if (!theRenderer->tlsAllocators()->hasLocalData()) {
        // RenderView has a sizeof 72
        // RenderCommand has a sizeof 128
        // QMatrix4x4 has a sizeof 68
        // May need to fine tune parameters passed to QFrameAllocator for best performances
        QFrameAllocator *allocator = new QFrameAllocator(128, 16, 128);
        theRenderer->tlsAllocators()->setLocalData(allocator);

        // Add the allocator to the renderer
        // so that it can be accessed
        theRenderer->addAllocator(allocator);
    }
}


/*!
 * Returns the a FrameAllocator for the caller thread.
 */
QFrameAllocator *Renderer::currentFrameAllocator()
{
    // return the QFrameAllocator for the current thread
    // It is never cleared as each renderview when it is destroyed
    // takes care of releasing anything that may have been allocated
    // using the allocator
    return m_tlsAllocators.localData();
}

void Renderer::destroyThreadLocalAllocator(void *renderer)
{
    Q_ASSERT(renderer);
    Renderer *theRenderer = static_cast<Renderer *>(renderer);
    if (theRenderer->tlsAllocators()->hasLocalData()) {
        QFrameAllocator *allocator = theRenderer->tlsAllocators()->localData();
        allocator->clear();
        // Setting the local data to null actually deletes the allocatorQeue
        // as the tls object takes ownership of pointers
        theRenderer->tlsAllocators()->setLocalData(Q_NULLPTR);
    }
}

// Called in RenderThread context by the run method of RenderThread
// RenderThread has locked the mutex already and unlocks it when this
// method termintates
void Renderer::initialize(QOpenGLContext *context)
{
    if (m_renderThread)
        m_waitForWindowToBeSetCondition.wait(mutex());

    QByteArray debugLoggingMode = qgetenv("QT3D_DEBUG_LOGGING");
    bool enableDebugLogging = !debugLoggingMode.isEmpty();

    m_graphicsContext.reset(new QGraphicsContext);
    m_graphicsContext->setRenderer(this);

    QSurfaceFormat sf = m_surface->format();
    if (enableDebugLogging)
        sf.setOption(QSurfaceFormat::DebugContext);


    QOpenGLContext* ctx = context ? context : new QOpenGLContext;
    if (!context) {
        qCDebug(Backend) << "Creating OpenGL context with format" << sf;
        ctx->setFormat(sf);
        if (ctx->create())
            qCDebug(Backend) << "OpenGL context created with actual format" << ctx->format();
        else
            qCWarning(Backend) << Q_FUNC_INFO << "OpenGL context creation failed";
    }
    m_graphicsContext->setOpenGLContext(ctx, m_surface);

    if (enableDebugLogging && ctx->makeCurrent(m_surface)) {
        bool supported = ctx->hasExtension("GL_KHR_debug");
        if (supported) {
            qCDebug(Backend) << "Qt3D: Enabling OpenGL debug logging";
            m_debugLogger.reset(new QOpenGLDebugLogger);
            if (m_debugLogger->initialize()) {
                QObject::connect(m_debugLogger.data(), &QOpenGLDebugLogger::messageLogged, &logOpenGLDebugMessage);
                QString mode = QString::fromLocal8Bit(debugLoggingMode);
                m_debugLogger->startLogging(mode.toLower().startsWith(QLatin1String("sync"))
                                            ? QOpenGLDebugLogger::SynchronousLogging
                                            : QOpenGLDebugLogger::AsynchronousLogging);

                Q_FOREACH (const QOpenGLDebugMessage &msg, m_debugLogger->loggedMessages())
                    logOpenGLDebugMessage(msg);
            }
        } else {
            qCDebug(Backend) << "Qt3D: OpenGL debug logging requested but GL_KHR_debug not supported";
        }
        ctx->doneCurrent();
    }

    // Awake setScenegraphRoot in case it was waiting
    m_waitForInitializationToBeCompleted.wakeOne();
    // Allow the aspect manager to proceed
    m_vsyncFrameAdvanceService->proceedToNextFrame();
}

/*!
    \internal

    Called in the context of the RenderThread to do any shutdown and cleanup
    that needs to be performed in the thread where the OpenGL context lives
*/
void Renderer::shutdown()
{
    // TO DO: Check that this works with iOs and other cases
    if (m_surface) {
        m_graphicsContext->makeCurrent(m_surface);
        // Stop and destroy the OpenGL logger
        if (m_debugLogger) {
            m_debugLogger->stopLogging();
            m_debugLogger.reset(Q_NULLPTR);
        }

        // Clean up the graphics context
        m_graphicsContext.reset(Q_NULLPTR);
        m_surface = Q_NULLPTR;
        qCDebug(Backend) << Q_FUNC_INFO << "Renderer properly shutdown";
    }
}

void Renderer::setFrameGraphRoot(const QNodeId &frameGraphRootUuid)
{
    m_frameGraphRootUuid = frameGraphRootUuid;
    qCDebug(Backend) << Q_FUNC_INFO << m_frameGraphRootUuid;
}

Render::FrameGraphNode *Renderer::frameGraphRoot() const
{
    FrameGraphNode **fgRoot = m_frameGraphManager->lookupResource(m_frameGraphRootUuid);
    if (fgRoot != Q_NULLPTR)
        return *fgRoot;
    return Q_NULLPTR;
}

// QAspectThread context
// Order of execution :
// 1) Initialize -> waiting for Window
// 2) setWindow -> waking Initialize || setSceneGraphRoot waiting
// 3) setWindow -> waking Initialize if setSceneGraphRoot was called before
// 4) Initialize resuming, performing initialization and waking up setSceneGraphRoot
// 5) setSceneGraphRoot called || setSceneGraphRoot resuming if it was waiting
void Renderer::setSceneGraphRoot(RenderEntity *sgRoot)
{
    Q_ASSERT(sgRoot);
    QMutexLocker lock(&m_mutex); // This waits until initialize and setSurface have been called
    if (m_graphicsContext == Q_NULLPTR) // If initialization hasn't been completed we must wait
        m_waitForInitializationToBeCompleted.wait(&m_mutex);

    m_renderSceneRoot = sgRoot;
    if (!m_renderSceneRoot)
        qCWarning(Backend) << "Failed to build render scene";
    m_renderSceneRoot->dump();
    qCDebug(Backend) << Q_FUNC_INFO << "DUMPING SCENE";

    buildDefaultTechnique();
    buildDefaultMaterial();

    // If that weren't for those lines, the renderer might not event need
    // to know about the renderer aspect
    m_rendererAspect->createBackendNode(m_defaultMaterial);
    m_rendererAspect->createBackendNode(m_defaultMaterial->effect());
    m_rendererAspect->createBackendNode(m_defaultTechnique);
    m_rendererAspect->createBackendNode(m_defaultTechnique->renderPasses().first());
    m_rendererAspect->createBackendNode(m_defaultTechnique->renderPasses().first()->shaderProgram());

    // We create backend resources for all the parameters
    Q_FOREACH (QParameter *p, m_defaultMaterial->parameters())
        m_rendererAspect->createBackendNode(p);
    Q_FOREACH (QParameter *p, m_defaultTechnique->parameters())
        m_rendererAspect->createBackendNode(p);
    Q_FOREACH (QParameter *p, m_defaultMaterial->effect()->parameters())
        m_rendererAspect->createBackendNode(p);


    m_defaultMaterialHandle = m_materialManager->lookupHandle(m_defaultMaterial->id());
    m_defaultEffectHandle = m_effectManager->lookupHandle(m_defaultMaterial->effect()->id());
    m_defaultTechniqueHandle = m_techniqueManager->lookupHandle(m_defaultTechnique->id());
    m_defaultRenderPassHandle = m_renderPassManager->lookupHandle(m_defaultTechnique->renderPasses().first()->id());
    m_defaultRenderShader = m_shaderManager->lookupResource(m_defaultTechnique->renderPasses().first()->shaderProgram()->id());
}

// Called in RenderAspect Thread context
// Cannot do OpenGLContext initialization here
void Renderer::setSurface(QSurface* surface)
{
    qCDebug(Backend) << Q_FUNC_INFO << QThread::currentThread();
    // Locking this mutex will wait until initialize() has been called by
    // RenderThread::run() and the RenderThread is waiting on the
    // m_waitForWindowToBeSetCondition condition.
    //
    // The first time this is called Renderer::setSurface will cause the
    // Renderer::initialize() function to continue execution in the context
    // of the Render Thread. On subsequent calls, just the surface will be
    // updated.

    // setSurface(Q_NULLPTR) is also called when the window is destroyed,
    // this is the opportunity to cleanup GL resources while we still have
    // a valid QGraphicContext

    // TODO: Remove the need for a valid surface from the renderer initialization
    // We can use an offscreen surface to create and assess the OpenGL context.
    // This should allow us to get rid of the "swapBuffers called on a non-exposed
    // window" warning that we sometimes see.
    QMutexLocker locker(&m_mutex);

    // We are about to be destroyed
    // cleanup GL now
    if (surface == Q_NULLPTR) {
        // Bail out of the main render loop. Ensure that even if the render thread
        // is waiting on RenderViews to be populated that we wake up the wait condition.
        // We check for termination immediately after being awaken.
        m_running.fetchAndStoreOrdered(0);
        if (m_renderThread) { // Pure Qt3D with RenderThread case
            m_submitRenderViewsSemaphore.release(1);
            m_renderThread->wait();
            // This will call shutdown on the Renderer and cleanup GL context
            // and then set the surface to Q_NULLPTR
            m_surface = surface;
        }
        // else we are dealing with the QtQuick2 / Scene3D in which case we
        // don't set the surface to Q_NULLPTR just yet as a call to
        // QRenderAspect::renderShutdown() -> Renderer::shutdown() should
        // follow and will take care of this
    } else { // Setting a valid window on initialization
        m_surface = surface;
        m_waitForWindowToBeSetCondition.wakeOne();
    }
}

void Renderer::render()
{
    // Traversing the framegraph tree from root to lead node
    // Allows us to define the rendering set up
    // Camera, RenderTarget ...

    // Utimately the renderer should be a framework
    // For the processing of the list of renderbins

    // Matrice update, bounding volumes computation ...
    // Should be jobs

    // Qt3D has 2 distincts node trees
    // One scene description
    // One framegraph description

    while (m_running.load() > 0) {
        doRender();
    }
}

void Renderer::doRender()
{

    // Render using current device state and renderer configuration
    submitRenderViews();

    // Reset the m_renderQueue so that we won't try to render
    // with a queue used by a previous frame with corrupted content
    m_renderQueue->reset();

    if (m_running.load()) { // Are we still running ?

        if (m_renderThread) {
            // If we are rendering using the render thread, make sure
            // that all the RenderViews, RenderCommands, UniformValues ...
            // have been completely destroyed and are leak free
            // Note: we cannot check for non render thread cases
            // (scene3d) as we aren't sure a full frame was previously submitted
            Q_FOREACH (QFrameAllocator *allocator, m_allocators)
                Q_ASSERT(allocator->isEmpty());
        }

        // We allow the RenderTickClock service to proceed to the next frame
        // In turn this will allow the aspect manager to request a new set of jobs
        // to be performed for each aspect
        m_vsyncFrameAdvanceService->proceedToNextFrame();
    }
}

// Called by RenderViewJobs
void Renderer::enqueueRenderView(Render::RenderView *renderView, int submitOrder)
{
    QMutexLocker locker(&m_mutex); // Prevent out of order execution
    // We cannot use a lock free primitive here because:
    // - QVector is not thread safe
    // - Even if the insert is made correctly, the isFrameComplete call
    //   could be invalid since depending on the order of execution
    //   the counter could be complete but the renderview not yet added to the
    //   buffer depending on whichever order the cpu decides to process this
    if (m_renderQueue->queueRenderView(renderView, submitOrder)) {
        if (m_renderThread && m_running.load())
            Q_ASSERT(m_submitRenderViewsSemaphore.available() == 0);
        m_submitRenderViewsSemaphore.release(1);
    }
}

bool Renderer::canRender() const
{
    // Make sure that we've not been told to terminate whilst waiting on
    // the above wait condition
    if (m_renderThread && !m_running.load()) {
        qCDebug(Rendering) << "RenderThread termination requested whilst waiting";
        return false;
    }

    // Make sure that the surface we are rendering too has not been unset
    // (probably due to the window being destroyed or changing QScreens).
    if (!m_surface) {
        qCDebug(Rendering) << "QSurface has been removed";
        return false;
    }

    return true;
}

// Happens in RenderThread context when all RenderViewJobs are done
void Renderer::submitRenderViews()
{
    // If we are using a render thread, make sure that
    // we've been told to render before rendering
    if (m_renderThread) { // Prevent ouf of order execution
        m_submitRenderViewsSemaphore.acquire(1);

        // Early return if we have been unlocked because of
        // shutdown
        if (!m_running.load())
            return;

        // When using Thread rendering, the semaphore should only
        // be released when the frame queue is complete and there's
        // something to render
        // The case of shutdown should have been handled just before
        Q_ASSERT(m_renderQueue->isFrameQueueComplete());
    } else {

        // When using synchronous rendering (QtQuick)
        // We are not sure that the frame queue is actually complete
        // Since a call to render may not be synched with the completions
        // of the RenderViewJobs
        // In such a case we return early, waiting for a next call with
        // the frame queue complete at this point
        QMutexLocker locker(&m_mutex);
        if (!m_renderQueue->isFrameQueueComplete())
            return ;
    }

    QElapsedTimer timer;
    quint64 queueElapsed = 0;
    timer.start();

    // Lock the mutex to protect access to m_surface and check if we are still set
    // to the running state and that we have a valid surface on which to draw
    QMutexLocker locker(&m_mutex);
    const QVector<Render::RenderView *> renderViews = m_renderQueue->nextFrameQueue();
    if (!canRender()) {
        qDeleteAll(renderViews);
        return;
    }

    const int renderViewsCount = renderViews.size();
    quint64 frameElapsed = queueElapsed;

    // Early return if there's actually nothing to render
    if (renderViewsCount <= 0)
        return;

    // We might not want to render on the default FBO
    bool boundFboIdValid = false;
    GLuint boundFboId = 0;
    QColor previousClearColor = renderViews.first()->clearColor();

    // Bail out if we cannot make the OpenGL context current (e.g. if the window has been destroyed)
    if (!m_graphicsContext->beginDrawing(m_surface, previousClearColor)) {
        qDeleteAll(renderViews);
        return;
    }

    if (!boundFboIdValid) {
        boundFboIdValid = true;
        boundFboId = m_graphicsContext->boundFrameBufferObject();
    }

    // Reset state to the default state
    m_graphicsContext->setCurrentStateSet(m_defaultRenderStateSet);

    qCDebug(Memory) << Q_FUNC_INFO << "rendering frame ";
    for (int i = 0; i < renderViewsCount; ++i) {
        // Initialize QGraphicsContext for drawing
        // If the RenderView has a RenderStateSet defined
        const RenderView *renderView = renderViews.at(i);

        // Set RenderView render state
        RenderStateSet *renderViewStateSet = renderView->stateSet();
        if (renderViewStateSet)
            m_graphicsContext->setCurrentStateSet(renderViewStateSet);

        // Set RenderTarget ...
        // Activate RenderTarget
        m_graphicsContext->activateRenderTarget(m_renderTargetManager->data(renderView->renderTargetHandle()),
                                                renderView->attachmentPack(), boundFboId);

        // Set clear color if different
        if (previousClearColor != renderView->clearColor()) {
            previousClearColor = renderView->clearColor();
            m_graphicsContext->clearColor(previousClearColor);
        }

        // Clear BackBuffer
        m_graphicsContext->clearBackBuffer(renderView->clearBuffer());
        // Set the Viewport
        m_graphicsContext->setViewport(renderView->viewport());

        // Execute the render commands
        executeCommands(renderView->commands());

        // executeCommands takes care of restoring the stateset to the value
        // of gc->currentContext() at the moment it was called (either
        // renderViewStateSet or m_defaultRenderStateSet)

        frameElapsed = timer.elapsed() - frameElapsed;
        qCDebug(Rendering) << Q_FUNC_INFO << "Submitted Renderview " << i + 1 << "/" << renderViewsCount  << "in " << frameElapsed << "ms";
        frameElapsed = timer.elapsed();
    }

    // Reset state to the default state if the last stateset is not the
    // defaultRenderStateSet
    if (m_graphicsContext->currentStateSet() != m_defaultRenderStateSet)
        m_graphicsContext->setCurrentStateSet(m_defaultRenderStateSet);

    m_graphicsContext->endDrawing(boundFboId == m_graphicsContext->defaultFBO());

    // Delete all the RenderViews which will clear the allocators
    // that were used for their allocation
    qDeleteAll(renderViews);

    queueElapsed = timer.elapsed() - queueElapsed;
    qCDebug(Rendering) << Q_FUNC_INFO << "Submission of Queue in " << queueElapsed << "ms <=> " << queueElapsed / renderViewsCount << "ms per RenderView <=> Avg " << 1000.0f / (queueElapsed * 1.0f/ renderViewsCount * 1.0f) << " RenderView/s";
    qCDebug(Rendering) << Q_FUNC_INFO << "Submission Completed in " << timer.elapsed() << "ms";
}

// Waits to be told to create jobs for the next frame
// Called by QRenderAspect jobsToExecute context of QAspectThread
QVector<QAspectJobPtr> Renderer::createRenderBinJobs()
{
    // Traverse the current framegraph. For each leaf node create a
    // RenderView and set its configuration then create a job to
    // populate the RenderView with a set of RenderCommands that get
    // their details from the RenderNodes that are visible to the
    // Camera selected by the framegraph configuration

    QVector<QAspectJobPtr> renderBinJobs;

    // Do not create any more jobs when the platform surface is gone.
    if (m_surface) {
        FrameGraphVisitor visitor;
        visitor.traverse(frameGraphRoot(), this, &renderBinJobs);

        // Set target number of RenderViews
        m_renderQueue->setTargetRenderViewCount(renderBinJobs.size());
    }
    return renderBinJobs;
}

// Returns a vector of jobs to be performed for dirty buffers
// 1 dirty buffer == 1 job, all job can be performed in parallel
QVector<QAspectJobPtr> Renderer::createRenderBufferJobs()
{
    const QVector<QNodeId> dirtyBuffers = m_bufferManager->dirtyBuffers();
    QVector<QAspectJobPtr> dirtyBuffersJobs;

    Q_FOREACH (const QNodeId &bufId, dirtyBuffers) {
        HBuffer bufferHandle = m_bufferManager->lookupHandle(bufId);
        if (!bufferHandle.isNull()) {
            // Create new buffer job
            LoadBufferJobPtr job(new LoadBufferJob(bufferHandle));
            job->setRenderer(this);
            dirtyBuffersJobs.push_back(job);
        }
    }

    return dirtyBuffersJobs;
}

QVector<QAspectJobPtr> Renderer::createGeometryRendererJobs()
{
    const QVector<QNodeId> dirtyGeometryRenderers = m_geometryRendererManager->dirtyGeometryRenderers();
    QVector<QAspectJobPtr> dirtyGeometryRendererJobs;

    Q_FOREACH (const QNodeId &geoRendererId, dirtyGeometryRenderers) {
        HGeometryRenderer geometryRendererHandle = m_geometryRendererManager->lookupHandle(geoRendererId);
        if (!geometryRendererHandle.isNull()) {
            LoadGeometryJobPtr job(new LoadGeometryJob(geometryRendererHandle));
            job->setRenderer(this);
            dirtyGeometryRendererJobs.push_back(job);
        }
    }

    return dirtyGeometryRendererJobs;
}

// Called during while traversing the FrameGraph for each leaf node context of QAspectThread
QAspectJobPtr Renderer::createRenderViewJob(FrameGraphNode *node, int submitOrderIndex)
{
    RenderViewJobPtr job(new RenderViewJob);
    job->setRenderer(this);
    job->setSurfaceSize(m_surface->size());
    job->setFrameGraphLeafNode(node);
    job->setSubmitOrderIndex(submitOrderIndex);
    return job;
}

// Called by RenderView->submit() in RenderThread context
void Renderer::executeCommands(const QVector<RenderCommand *> &commands)
{
    // Render drawing commands

    // Use the graphicscontext to submit the commands to the underlying
    // graphics API (OpenGL)

    // Save the RenderView base stateset
    RenderStateSet *globalState = m_graphicsContext->currentStateSet();

    Q_FOREACH (RenderCommand *command, commands) {

        // Check if we have a valid GeometryRenderer + Geometry
        RenderGeometry *rGeometry = m_geometryManager->data(command->m_geometry);
        RenderGeometryRenderer *rGeometryRenderer = m_geometryRendererManager->data(command->m_geometryRenderer);
        const bool hasGeometryRenderer = rGeometry != Q_NULLPTR && rGeometryRenderer != Q_NULLPTR && !rGeometry->attributes().isEmpty();

        if (!hasGeometryRenderer) {
            qCWarning(Rendering) << "RenderCommand should have a mesh to render";
            continue;
        }

        RenderShader *shader = m_shaderManager->data(command->m_shader);
        if (shader == Q_NULLPTR) {
            shader = m_defaultRenderShader;
            command->m_parameterAttributeToShaderNames = m_defaultParameterToGLSLAttributeNames;
            command->m_uniforms = m_defaultUniformPack;
        }

        // The VAO should be created only once for a QGeometry and a ShaderProgram
        // Manager should have a VAO Manager that are indexed by QMeshData and Shader
        // RenderCommand should have a handle to the corresponding VAO for the Mesh and Shader
        QOpenGLVertexArrayObject *vao = Q_NULLPTR;
        if (m_graphicsContext->supportsVAO()) {
            command->m_vao = m_vaoManager->lookupHandle(QPair<HGeometry, HShader>(command->m_geometry, command->m_shader));
            if (command->m_vao.isNull()) {
                qCDebug(Rendering) << Q_FUNC_INFO << "Allocating new VAO";
                command->m_vao = m_vaoManager->getOrAcquireHandle(QPair<HGeometry, HShader>(command->m_geometry, command->m_shader));
                *(m_vaoManager->data(command->m_vao)) = new QOpenGLVertexArrayObject();
            }
            vao = *(m_vaoManager->data(command->m_vao));
            Q_ASSERT(vao);
        }

        //// We activate the shader here
        // This will fill the attributes & uniforms info the first time the shader is loaded
        m_graphicsContext->activateShader(shader);

        //// Initialize GL
        // The initialization is performed only once parameters in the command are set
        // Which indicates that the shader has been initialized and that renderview jobs were able to retrieve
        // Uniform and Attributes info from the shader
        // Otherwise we might create a VAO without attribute bindings as the RenderCommand had no way to know about attributes
        // Before the shader was loader
        RenderAttribute *indexAttribute = Q_NULLPTR;
        bool specified = false;
        const bool requiresVAOUpdate = (!vao || !vao->isCreated()) || (rGeometry->isDirty() || rGeometryRenderer->isDirty());
        GLsizei primitiveCount = rGeometryRenderer->primitiveCount();

        // Append dirty Geometry to temporary vector
        // so that its dirtiness can be unset later
        if (rGeometry->isDirty())
            m_dirtyGeometry.push_back(rGeometry);

        if (!command->m_parameterAttributeToShaderNames.isEmpty()) {
            specified = true;
            if (vao) {
                if (!vao->isCreated())
                    vao->create();
                vao->bind();
                qCDebug(Rendering) << Q_FUNC_INFO << "Creating new VAO";
            }

            // Update or set Attributes and Buffers for the given rGeometry and Command
            indexAttribute = updateBuffersAndAttributes(rGeometry, command, primitiveCount, requiresVAOUpdate);
        }

        //// Update program uniforms
        m_graphicsContext->setUniforms(command->m_uniforms);

        //// Draw Calls
        // Set state
        RenderStateSet *localState = command->m_stateSet;

        // Merge the RenderCommand state with the globalState of the RenderView
        // Or restore the globalState if no stateSet for the RenderCommand
        if (localState != Q_NULLPTR) {
            command->m_stateSet->merge(globalState);
            m_graphicsContext->setCurrentStateSet(command->m_stateSet);
        } else {
            m_graphicsContext->setCurrentStateSet(globalState);
        }
        // All Uniforms for a pass are stored in the QUniformPack of the command
        // Uniforms for Effect, Material and Technique should already have been correctly resolved
        // at that point
        if (specified || (vao && vao->isCreated())) {
            const GLint primType = rGeometryRenderer->primitiveType();
            const bool drawInstanced = rGeometryRenderer->instanceCount() > 1;
            const bool drawIndexed = indexAttribute != Q_NULLPTR;
            const GLint indexType = drawIndexed ? QGraphicsContext::glDataTypeFromAttributeDataType(indexAttribute->dataType()) : 0;

            if (rGeometryRenderer->primitiveType() == QGeometryRenderer::Patches)
                m_graphicsContext->setVerticesPerPatch(rGeometry->verticesPerPatch());

            if (rGeometryRenderer->primitiveRestart())
                m_graphicsContext->enablePrimitiveRestart(rGeometryRenderer->restartIndex());

            // TO DO: Add glMulti Draw variants
            if (!drawInstanced) { // Non instanced Rendering
                if (drawIndexed)
                    m_graphicsContext->drawElements(primType,
                                                    primitiveCount,
                                                    indexType,
                                                    reinterpret_cast<void*>(indexAttribute->byteOffset()),
                                                    rGeometryRenderer->baseVertex());

                else
                    m_graphicsContext->drawArrays(primType, 0, primitiveCount);
            } else { // Instanced Rendering
                if (drawIndexed)
                    m_graphicsContext->drawElementsInstanced(primType,
                                                             primitiveCount,
                                                             indexType,
                                                             reinterpret_cast<void*>(indexAttribute->byteOffset()),
                                                             rGeometryRenderer->instanceCount());
                else
                    m_graphicsContext->drawArraysInstanced(primType,
                                                           rGeometryRenderer->baseInstance(),
                                                           primitiveCount,
                                                           rGeometryRenderer->instanceCount());
            }

            int err = m_graphicsContext->openGLContext()->functions()->glGetError();
            if (err)
                qCWarning(Rendering) << "GL error after drawing mesh:" << QString::number(err, 16);

            if (rGeometryRenderer->primitiveRestart())
                m_graphicsContext->disablePrimitiveRestart();

            // Maybe we could cache the VAO and release it only at the end of the exectute frame
            // in case we are always reusing the same one ?

            if (vao && vao->isCreated())
                vao->release();

            // Unset dirtiness on rGeometryRenderer only
            // The rGeometry may be shared by several rGeometryRenderer
            // so we cannot unset its dirtiness at this point
            rGeometryRenderer->unsetDirty();

        }
    } // end of RenderCommands loop

    // Reset to the state we were in before executing the render commands
    m_graphicsContext->setCurrentStateSet(globalState);

    // Unset dirtiness on Geometry and Attributes
    Q_FOREACH (RenderAttribute *attribute, m_dirtyAttributes)
        attribute->unsetDirty();
    m_dirtyAttributes.clear();

    Q_FOREACH (RenderGeometry *geometry, m_dirtyGeometry)
        geometry->unsetDirty();
    m_dirtyGeometry.clear();
}

RenderAttribute *Renderer::updateBuffersAndAttributes(RenderGeometry *geometry, RenderCommand *command, GLsizei &count, bool forceUpdate)
{
    RenderAttribute *indexAttribute = Q_NULLPTR;
    uint estimatedCount = 0;

    Q_FOREACH (const QNodeId &attributeId, geometry->attributes()) {
        // TO DO: Improvement we could store handles and use the non locking policy on the attributeManager
        RenderAttribute *attribute = attributeManager()->lookupResource(attributeId);

        if (attribute == Q_NULLPTR)
            continue;

        RenderBuffer *buffer = bufferManager()->lookupResource(attribute->bufferId());

        if (buffer == Q_NULLPTR)
            continue;

        if (buffer->isDirty()) {
            // Reupload buffer data
            m_graphicsContext->updateBuffer(buffer);

            // Append buffer to temporary vector so that its dirtiness
            // can be cleared at the end of the frame
            buffer->unsetDirty();
        }

        // Update attribute and create buffer if needed

        // Index Attribute
        if (attribute->attributeType() == QAttribute::IndexAttribute) {
            if (attribute->isDirty() || forceUpdate)
                m_graphicsContext->specifyIndices(buffer);
            indexAttribute = attribute;
            // Vertex Attribute
        } else if (command->m_parameterAttributeToShaderNames.contains(attribute->name())) {
            if (attribute->isDirty() || forceUpdate)
                m_graphicsContext->specifyAttribute(attribute, buffer, command->m_parameterAttributeToShaderNames.value(attribute->name()));
            estimatedCount = qMax(attribute->count(), estimatedCount);
        }

        // Append attribute to temporary vector so that its dirtiness
        // can be cleared at the end of the frame
        m_dirtyAttributes.push_back(attribute);

        // Note: We cannont call unsertDirty on the Attributeat this
        // point as we don't know if the attributes are being shared
        // with other geometry / geometryRenderer in which case they still
        // should remain dirty so that VAO for these commands are properly
        // updated
    }

    // If the count was not specified by the geometry renderer
    // we set it to what we estimated it to be
    if (count == 0)
        count = indexAttribute ? indexAttribute->count() : estimatedCount;
    return indexAttribute;
}

void Renderer::addAllocator(QFrameAllocator *allocator)
{
    QMutexLocker lock(&m_mutex);
    m_allocators.append(allocator);
}

QOpenGLFilter *Renderer::contextInfo() const
{
    return m_graphicsContext->contextInfo();
}

} // namespace Render
} // namespace Qt3D

QT_END_NAMESPACE