QQuickRenderControl RHI 예제

    QDialog apiSelect;
    QVBoxLayout *selLayout = new QVBoxLayout;
    selLayout->addWidget(new QLabel(QObject::tr("Select graphics API to use")));
    QListWidget *apiList = new QListWidget;
    QVarLengthArray<QSGRendererInterface::GraphicsApi, 5> apiValues;
#ifdef Q_OS_WIN
    apiList->addItem("Direct3D 11");
    apiValues.append(QSGRendererInterface::Direct3D11);
    apiList->addItem("Direct3D 12");
    apiValues.append(QSGRendererInterface::Direct3D12);
#endif
#if QT_CONFIG(metal)
    apiList->addItem("Metal");
    apiValues.append(QSGRendererInterface::Metal);
#endif
#if QT_CONFIG(vulkan)
    apiList->addItem("Vulkan");
    apiValues.append(QSGRendererInterface::Vulkan);
#endif
#if QT_CONFIG(opengl)
    apiList->addItem("OpenGL / OpenGL ES");
    apiValues.append(QSGRendererInterface::OpenGL);
#endif
    if (apiValues.isEmpty()) {
        QMessageBox::critical(nullptr, QObject::tr("No 3D graphics API"), QObject::tr("No 3D graphics APIs are supported in this Qt build"));
        return 1;
    }

void MainWindow::load(const QString&filename)
{
    reset();

    m_renderControl.reset(new QQuickRenderControl);
    m_scene.reset(new QQuickWindow(m_renderControl.get()));

    // 기본 3D API에서 지원하는 경우, QRhiCommandBuffer에서 lastCompletedGpuTime()을 활성화합니다
    QQuickGraphicsConfiguration config;
    config.setTimestamps(true);
    m_scene->setGraphicsConfiguration(config);

#if QT_CONFIG(vulkan)
    if (m_scene->graphicsApi()== QSGRendererInterface::Vulkan)
        m_scene->setVulkanInstance(m_vulkanInstance);
#endif

    m_qmlEngine.reset(new QQmlEngine);
    m_qmlComponent.reset(new QQmlComponent(m_qmlEngine.get(), QUrl::fromLocalFile(filename)));
    if (m_qmlComponent->isError()) {
        for (const QQmlError&error: m_qmlComponent->errors())
            qWarning() << error.url() << error.line() << error;
        QMessageBox::critical(this, tr("QML 씬을 불러올 수 없습니다"), tr("%1을 불러오는 데 실패했습니다").arg(filename));
        reset();
        return;
    }

    QObject*rootObject = m_qmlComponent->create();
    if (m_qmlComponent->isError()) {
        for (const QQmlError&error: m_qmlComponent->errors())
            qWarning() << error.url() << error.line() << error;
        QMessageBox::critical(this, tr("QML 장면을 불러올 수 없습니다"), tr("컴포넌트 생성에 실패했습니다"));
        reset();
        return;
    }

    QQuickItem*rootItem = qobject_cast<QQuickItem*>(rootObject);
    if (!rootItem) {
        // 루트 객체가 Window인 경우, 화면에 표시된 창을 제거합니다.
        if (QQuickWindow*w = qobject_cast<QQuickWindow*>(rootObject))
            delete w;
        QMessageBox::critical(this,
                              tr("QML 씬의 루트 항목이 유효하지 않습니다"),
                              tr("루트 객체가 QQuickItem이 아닙니다. 이 씬에 Window가 포함된 경우, 이러한 씬은 지원되지 않는다는 점에 유의하십시오."));
        reset();
        return;
    }

    if (rootItem->size().width() < 16)
        rootItem->setSize(QSizeF(640, 360));

    m_scene->contentItem()->setSize(rootItem->size());
    m_scene->setGeometry(0, 0, rootItem->width(), rootItem->height());

    rootItem->setParentItem(m_scene->contentItem());

    m_statusMsg->setText(tr("QML 장면이 로드되었습니다"));

    const bool initSuccess = m_renderControl->initialize();
    if (!initSuccess) {
        QMessageBox::critical(this, tr("Cannot initialize renderer"), tr("QQuickRenderControl::initialize() failed"));
        reset();
        return;
    }

    const QSGRendererInterface::GraphicsApi api = m_scene->rendererInterface()->graphicsApi();
    switch (api) {
    case QSGRendererInterface::OpenGL:
        m_apiMsg->setText(tr("OpenGL"));
        break;
    case QSGRendererInterface::Direct3D11:
        m_apiMsg->setText(tr("D3D11"));
        break;
    case QSGRendererInterface::Direct3D12:
        m_apiMsg->setText(tr("D3D12"));
        break;
    case QSGRendererInterface::Vulkan:
        m_apiMsg->setText(tr("Vulkan"));
        break;
    case QSGRendererInterface::Metal:
        m_apiMsg->setText(tr("Metal"));
        break;
    default:
        m_apiMsg->setText(tr("Unknown 3D API"));
        break;
    }

    QRhi *rhi = m_renderControl->rhi();
    if (!rhi) {
        QMessageBox::critical(this, tr("Cannot render"), tr("No QRhi from QQuickRenderControl"));
        reset();
        return;
    }

    m_driverInfoMsg->setText(QString::fromUtf8(rhi->driverInfo().deviceName));

    const QSize pixelSize = rootItem->size().toSize(); // no scaling, i.e. the item size is in pixels

    m_texture.reset(rhi->newTexture(QRhiTexture::RGBA8, pixelSize, 1,
                                    QRhiTexture::RenderTarget | QRhiTexture::UsedAsTransferSource));
    if (!m_texture->create()) {
        QMessageBox::critical(this, tr("Cannot render"), tr("Cannot create texture object"));
        reset();
        return;
    }

    m_ds.reset(rhi->newRenderBuffer(QRhiRenderBuffer::DepthStencil, pixelSize, 1));
    if (!m_ds->create()) {
        QMessageBox::critical(this, tr("Cannot render"), tr("Cannot create depth-stencil buffer"));
        reset();
        return;
    }

    QRhiTextureRenderTargetDescription rtDesc(QRhiColorAttachment(m_texture.get()));
    rtDesc.setDepthStencilBuffer(m_ds.get());
    m_rt.reset(rhi->newTextureRenderTarget(rtDesc));
    m_rpDesc.reset(m_rt->newCompatibleRenderPassDescriptor());
    m_rt->setRenderPassDescriptor(m_rpDesc.get());
    if (!m_rt->create()) {
        QMessageBox::critical(this, tr("Cannot render"), tr("Cannot create render target"));
        reset();
        return;
    }

    m_scene->setRenderTarget(QQuickRenderTarget::fromRhiRenderTarget(m_rt.get()));

    QElapsedTimer cpuTimer;
    cpuTimer.start();

    m_renderControl->polishItems();

    m_renderControl->beginFrame();

    m_renderControl->sync();
    m_renderControl->render();

    QRhi *rhi = m_renderControl->rhi();
    QRhiReadbackResult readResult;
    QRhiResourceUpdateBatch *readbackBatch = rhi->nextResourceUpdateBatch();
    readbackBatch->readBackTexture(m_texture.get(), &readResult);
    m_renderControl->commandBuffer()->resourceUpdate(readbackBatch);

    m_renderControl->endFrame();

    const double gpuRenderTimeMs = m_renderControl->commandBuffer()->lastCompletedGpuTime() * 1000.0;
    const double cpuRenderTimeMs = cpuTimer.nsecsElapsed() / 1000000.0;

    // m_renderControl->begin/endFrame() is based on QRhi's
    // begin/endOffscreenFrame() under the hood, meaning it does not do
    // pipelining, unlike swapchain-based frames, and therefore the readback is
    // guaranteed to complete once endFrame() returns.
    QImage wrapperImage(reinterpret_cast<const uchar *>(readResult.data.constData()),
                    readResult.pixelSize.width(), readResult.pixelSize.height(),
                    QImage::Format_RGBA8888_Premultiplied);
    QImage result;
    if (rhi->isYUpInFramebuffer())
        result = wrapperImage.flipped();
    else
        result = wrapperImage.copy();

class AnimationDriver : public QAnimationDriver
{
public:
    AnimationDriver(QObject *parent = nullptr)
        : QAnimationDriver(parent),
          m_step(16)
    {
    }

    void setStep(int milliseconds)
    {
        m_step = milliseconds;
    }

    void advance() override
    {
        m_elapsed += m_step;
        advanceAnimation();
    }

    qint64 elapsed() const override
    {
        return m_elapsed;
    }

private:
    int m_step;
    qint64 m_elapsed = 0;
};

    QSlider *animSlider = new QSlider;
    animSlider->setOrientation(Qt::Horizontal);
    animSlider->setMinimum(1);
    animSlider->setMaximum(1000);
    QLabel *animLabel = new QLabel;
    QObject::connect(animSlider, &QSlider::valueChanged, animSlider, [this, animLabel, animSlider] {
        if (m_animationDriver)
            m_animationDriver->setStep(animSlider->value());
        animLabel->setText(tr("Simulated elapsed time per frame: %1 ms").arg(animSlider->value()));
    });
    animSlider->setValue(16);
    QCheckBox *animCheckBox = new QCheckBox(tr("Custom animation driver"));
    animCheckBox->setToolTip(tr("Note: Installing the custom animation driver makes widget drawing unreliable, depending on the platform.\n"
                                "This is due to widgets themselves relying on QPropertyAnimation and similar, which are driven by the same QAnimationDriver.\n"
                                "In any case, the functionality of the widgets are not affected, just the rendering may lag behind.\n"
                                "When not checked, Qt Quick animations advance based on the system time, i.e. the time elapsed since the last press of the Next button."));
    QObject::connect(animCheckBox, &QCheckBox::checkStateChanged, animCheckBox, [this, animCheckBox, animSlider, animLabel] {
        if (animCheckBox->isChecked()) {
            animSlider->setEnabled(true);
            animLabel->setEnabled(true);
            m_animationDriver = new AnimationDriver(this);
            m_animationDriver->install();
            m_animationDriver->setStep(animSlider->value());
        } else {
            animSlider->setEnabled(false);
            animLabel->setEnabled(false);
            delete m_animationDriver;
            m_animationDriver = nullptr;
        }
    });
    animSlider->setEnabled(false);
    animLabel->setEnabled(false);
    controlLayout->addWidget(animCheckBox);
    controlLayout->addWidget(animLabel);
    controlLayout->addWidget(animSlider);

void MainWindow::stepAnimations()
{
    if (m_animationDriver) {
        // Now the Qt Quick scene will think that <slider value> milliseconds have
        // elapsed and update animations accordingly when doing the next frame.
        m_animationDriver->advance();
    }
}