10 files changed, 753 insertions, 0 deletions
diff --git a/examples/quick/scenegraph/metalunderqml/doc/images/metalunderqml-example.jpg b/examples/quick/scenegraph/metalunderqml/doc/images/metalunderqml-example.jpg
new file mode 100644
index 0000000000..98085773de
--- /dev/null
+++ b/examples/quick/scenegraph/metalunderqml/doc/images/metalunderqml-example.jpg
diff --git a/examples/quick/scenegraph/metalunderqml/doc/src/metalunderqml.qdoc b/examples/quick/scenegraph/metalunderqml/doc/src/metalunderqml.qdoc
new file mode 100644
index 0000000000..fb28270315
--- /dev/null
+++ b/examples/quick/scenegraph/metalunderqml/doc/src/metalunderqml.qdoc
@@ -0,0 +1,69 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the documentation of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:FDL$
+** Commercial License Usage
+** 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
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Free Documentation License Usage
+** Alternatively, this file may be used under the terms of the GNU Free
+** Documentation License version 1.3 as published by the Free Software
+** Foundation and appearing in the file included in the packaging of
+** this file. Please review the following information to ensure
+** the GNU Free Documentation License version 1.3 requirements
+** will be met: https://www.gnu.org/licenses/fdl-1.3.html.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+/*!
+    \example scenegraph/metalunderqml
+    \title Scene Graph - Metal Under QML
+    \ingroup qtquickexamples
+    \brief Shows how to render directly with Metal under a Qt Quick scene.
+
+    \image metalunderqml-example.jpg
+
+    The Metal Under QML example shows how an application can make use
+    of the \l QQuickWindow::beforeRendering() and \l
+    QQuickWindow::beforeRenderPassRecording() signals to draw custom
+    Metal content under a Qt Quick scene. This signal is emitted at
+    the start of every frame, before the scene graph starts its
+    rendering, thus any Metal draw calls that are made as a response
+    to this signal, will stack under the Qt Quick items. There are two
+    signals, because the custom Metal commands are recorded onto the
+    same command buffer with the same render command encoder that the
+    scene graph uses. beforeRendering() on its own is not sufficient
+    for this because it gets emitted at the start of the frame, before
+    having an
+    \l{https://developer.apple.com/documentation/metal/mtlrendercommandencoder}{MTLRenderCommandEncoder}
+    available. By also connecting to beforeRenderPassRecording(), the
+    application can gain access to the necessary native objects.
+
+    As an alternative, applications that wish to render Metal content
+    on top of the Qt Quick scene, can do so by connecting to the \l
+    QQuickWindow::afterRendering() and \l
+    QQuickWindow::afterRenderPassRecording() signals.
+
+    In this example, we will also see how it is possible to have
+    values that are exposed to QML which affect the Metal
+    rendering. We animate the threshold value using a NumberAnimation
+    in the QML file and this value is used by the Metal shader
+    program that draws the squircles.
+
+    The example is equivalent in most ways to the \l{Scene Graph - OpenGL Under
+    QML}{OpenGL Under QML}, \l{Scene Graph - Direct3D 11 Under QML}{Direct3D 11
+    Under QML}, and \l{Scene Graph - Vulkan Under QML}{Vulkan Under QML}
+    examples, they all render the same custom content, just via different
+    native APIs.
+
+  */
diff --git a/examples/quick/scenegraph/metalunderqml/main.cpp b/examples/quick/scenegraph/metalunderqml/main.cpp
new file mode 100644
index 0000000000..5ad337abb1
--- /dev/null
+++ b/examples/quick/scenegraph/metalunderqml/main.cpp
@@ -0,0 +1,69 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the demonstration applications of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** Commercial License Usage
+** 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
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** BSD License Usage
+** Alternatively, you may use this file under the terms of the BSD license
+** as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of The Qt Company Ltd nor the names of its
+**     contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QGuiApplication>
+#include <QtQuick/QQuickView>
+#include "metalsquircle.h"
+
+int main(int argc, char **argv)
+{
+    QGuiApplication app(argc, argv);
+
+    qmlRegisterType<MetalSquircle>("MetalUnderQML", 1, 0, "MetalSquircle");
+
+    QQuickWindow::setSceneGraphBackend(QSGRendererInterface::MetalRhi);
+
+    QQuickView view;
+    view.setResizeMode(QQuickView::SizeRootObjectToView);
+    view.setSource(QUrl("qrc:///scenegraph/metalunderqml/main.qml"));
+    view.show();
+
+    return app.exec();
+}
diff --git a/examples/quick/scenegraph/metalunderqml/main.qml b/examples/quick/scenegraph/metalunderqml/main.qml
new file mode 100644
index 0000000000..d41a0b8e81
--- /dev/null
+++ b/examples/quick/scenegraph/metalunderqml/main.qml
@@ -0,0 +1,89 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the demonstration applications of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** Commercial License Usage
+** 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
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** BSD License Usage
+** Alternatively, you may use this file under the terms of the BSD license
+** as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of The Qt Company Ltd nor the names of its
+**     contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+//! [1]
+import QtQuick 2.0
+import MetalUnderQML 1.0
+
+Item {
+
+    width: 320
+    height: 480
+
+    MetalSquircle {
+        SequentialAnimation on t {
+            NumberAnimation { to: 1; duration: 2500; easing.type: Easing.InQuad }
+            NumberAnimation { to: 0; duration: 2500; easing.type: Easing.OutQuad }
+            loops: Animation.Infinite
+            running: true
+        }
+    }
+//! [1] //! [2]
+    Rectangle {
+        color: Qt.rgba(1, 1, 1, 0.7)
+        radius: 10
+        border.width: 1
+        border.color: "white"
+        anchors.fill: label
+        anchors.margins: -10
+    }
+
+    Text {
+        id: label
+        color: "black"
+        wrapMode: Text.WordWrap
+        text: "The background here is a squircle rendered with raw Metal using the beforeRendering() and beforeRenderPassRecording() signals in QQuickWindow. This text label and its border is rendered using QML"
+        anchors.right: parent.right
+        anchors.left: parent.left
+        anchors.bottom: parent.bottom
+        anchors.margins: 20
+    }
+}
+//! [2]
diff --git a/examples/quick/scenegraph/metalunderqml/metalsquircle.h b/examples/quick/scenegraph/metalunderqml/metalsquircle.h
new file mode 100644
index 0000000000..43c4afad21
--- /dev/null
+++ b/examples/quick/scenegraph/metalunderqml/metalsquircle.h
@@ -0,0 +1,86 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the demonstration applications of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** Commercial License Usage
+** 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
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** BSD License Usage
+** Alternatively, you may use this file under the terms of the BSD license
+** as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of The Qt Company Ltd nor the names of its
+**     contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef METALSQUIRCLE_H
+#define METALSQUIRCLE_H
+
+#include <QtQuick/QQuickItem>
+
+class SquircleRenderer;
+
+class MetalSquircle : public QQuickItem
+{
+    Q_OBJECT
+    Q_PROPERTY(qreal t READ t WRITE setT NOTIFY tChanged)
+
+public:
+    MetalSquircle();
+
+    qreal t() const { return m_t; }
+    void setT(qreal t);
+
+signals:
+    void tChanged();
+
+public slots:
+    void sync();
+    void cleanup();
+
+private slots:
+    void handleWindowChanged(QQuickWindow *win);
+
+private:
+    void releaseResources() override;
+
+    qreal m_t;
+    SquircleRenderer *m_renderer = nullptr;
+};
+
+#endif
diff --git a/examples/quick/scenegraph/metalunderqml/metalsquircle.mm b/examples/quick/scenegraph/metalunderqml/metalsquircle.mm
new file mode 100644
index 0000000000..5ca6daa01a
--- /dev/null
+++ b/examples/quick/scenegraph/metalunderqml/metalsquircle.mm
@@ -0,0 +1,369 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the demonstration applications of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** Commercial License Usage
+** 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
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** BSD License Usage
+** Alternatively, you may use this file under the terms of the BSD license
+** as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of The Qt Company Ltd nor the names of its
+**     contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "metalsquircle.h"
+#include <QtCore/QRunnable>
+#include <QtQuick/QQuickWindow>
+
+#include <Metal/Metal.h>
+
+class SquircleRenderer : public QObject
+{
+    Q_OBJECT
+public:
+    SquircleRenderer();
+    ~SquircleRenderer();
+
+    void setT(qreal t) { m_t = t; }
+    void setViewportSize(const QSize &size) { m_viewportSize = size; }
+    void setWindow(QQuickWindow *window) { m_window = window; }
+
+public slots:
+    void frameStart();
+    void mainPassRecordingStart();
+
+private:
+    enum Stage {
+        VertexStage,
+        FragmentStage
+    };
+    void prepareShader(Stage stage);
+    using FuncAndLib = QPair<id<MTLFunction>, id<MTLLibrary> >;
+    FuncAndLib compileShaderFromSource(const QByteArray &src, const QByteArray &entryPoint);
+    void init(int framesInFlight);
+
+    QSize m_viewportSize;
+    qreal m_t;
+    QQuickWindow *m_window;
+
+    QByteArray m_vert;
+    QByteArray m_vertEntryPoint;
+    QByteArray m_frag;
+    QByteArray m_fragEntryPoint;
+
+    bool m_initialized = false;
+    id<MTLDevice> m_device;
+    id<MTLBuffer> m_vbuf;
+    id<MTLBuffer> m_ubuf[3];
+    FuncAndLib m_vs;
+    FuncAndLib m_fs;
+    id<MTLRenderPipelineState> m_pipeline;
+};
+
+MetalSquircle::MetalSquircle()
+    : m_t(0)
+    , m_renderer(nullptr)
+{
+    connect(this, &QQuickItem::windowChanged, this, &MetalSquircle::handleWindowChanged);
+}
+
+void MetalSquircle::setT(qreal t)
+{
+    if (t == m_t)
+        return;
+    m_t = t;
+    emit tChanged();
+    if (window())
+        window()->update();
+}
+
+void MetalSquircle::handleWindowChanged(QQuickWindow *win)
+{
+    if (win) {
+        connect(win, &QQuickWindow::beforeSynchronizing, this, &MetalSquircle::sync, Qt::DirectConnection);
+        connect(win, &QQuickWindow::sceneGraphInvalidated, this, &MetalSquircle::cleanup, Qt::DirectConnection);
+
+        // Ensure we start with cleared to black. The squircle's blend mode relies on this.
+        win->setColor(Qt::black);
+    }
+}
+
+SquircleRenderer::SquircleRenderer()
+    : m_t(0)
+{
+    m_vbuf = nil;
+
+    for (int i = 0; i < 3; ++i)
+        m_ubuf[i] = nil;
+
+    m_vs.first = nil;
+    m_vs.second = nil;
+
+    m_fs.first = nil;
+    m_fs.second = nil;
+}
+
+// The safe way to release custom graphics resources is to both connect to
+// sceneGraphInvalidated() and implement releaseResources(). To support
+// threaded render loops the latter performs the SquircleRenderer destruction
+// via scheduleRenderJob(). Note that the MetalSquircle may be gone by the time
+// the QRunnable is invoked.
+
+void MetalSquircle::cleanup()
+{
+    delete m_renderer;
+    m_renderer = nullptr;
+}
+
+class CleanupJob : public QRunnable
+{
+public:
+    CleanupJob(SquircleRenderer *renderer) : m_renderer(renderer) { }
+    void run() override { delete m_renderer; }
+private:
+    SquircleRenderer *m_renderer;
+};
+
+void MetalSquircle::releaseResources()
+{
+    window()->scheduleRenderJob(new CleanupJob(m_renderer), QQuickWindow::BeforeSynchronizingStage);
+    m_renderer = nullptr;
+}
+
+SquircleRenderer::~SquircleRenderer()
+{
+    qDebug("cleanup");
+
+    [m_vbuf release];
+    for (int i = 0; i < 3; ++i)
+        [m_ubuf[i] release];
+
+    [m_vs.first release];
+    [m_vs.second release];
+
+    [m_fs.first release];
+    [m_fs.second release];
+}
+
+void MetalSquircle::sync()
+{
+    if (!m_renderer) {
+        m_renderer = new SquircleRenderer;
+        // Initializing resources is done before starting to encode render
+        // commands, regardless of wanting an underlay or overlay.
+        connect(window(), &QQuickWindow::beforeRendering, m_renderer, &SquircleRenderer::frameStart, Qt::DirectConnection);
+        // Here we want an underlay and therefore connect to
+        // beforeRenderPassRecording. Changing to afterRenderPassRecording
+        // would render the squircle on top (overlay).
+        connect(window(), &QQuickWindow::beforeRenderPassRecording, m_renderer, &SquircleRenderer::mainPassRecordingStart, Qt::DirectConnection);
+    }
+    m_renderer->setViewportSize(window()->size() * window()->devicePixelRatio());
+    m_renderer->setT(m_t);
+    m_renderer->setWindow(window());
+}
+
+void SquircleRenderer::frameStart()
+{
+    QSGRendererInterface *rif = m_window->rendererInterface();
+
+    // We are not prepared for anything other than running with the RHI and its Metal backend.
+    Q_ASSERT(rif->graphicsApi() == QSGRendererInterface::MetalRhi);
+
+    m_device = (id<MTLDevice>) rif->getResource(m_window, QSGRendererInterface::DeviceResource);
+    Q_ASSERT(m_device);
+
+    if (m_vert.isEmpty())
+        prepareShader(VertexStage);
+    if (m_frag.isEmpty())
+        prepareShader(FragmentStage);
+
+    if (!m_initialized)
+        init(m_window->graphicsStateInfo().framesInFlight);
+}
+
+static const float vertices[] = {
+    -1, -1,
+    1, -1,
+    -1, 1,
+    1, 1
+};
+
+const int UBUF_SIZE = 4;
+
+void SquircleRenderer::mainPassRecordingStart()
+{
+    // This example demonstrates the simple case: prepending some commands to
+    // the scenegraph's main renderpass. It does not create its own passes,
+    // rendertargets, etc. so no synchronization is needed.
+
+    const QQuickWindow::GraphicsStateInfo &stateInfo(m_window->graphicsStateInfo());
+
+    QSGRendererInterface *rif = m_window->rendererInterface();
+    id<MTLRenderCommandEncoder> encoder = (id<MTLRenderCommandEncoder>) rif->getResource(
+                m_window, QSGRendererInterface::CommandEncoderResource);
+    Q_ASSERT(encoder);
+
+    m_window->beginExternalCommands();
+
+    void *p = [m_ubuf[stateInfo.currentFrameSlot] contents];
+    float t = m_t;
+    memcpy(p, &t, 4);
+
+    MTLViewport vp;
+    vp.originX = 0;
+    vp.originY = 0;
+    vp.width = m_viewportSize.width();
+    vp.height = m_viewportSize.height();
+    vp.znear = 0;
+    vp.zfar = 1;
+    [encoder setViewport: vp];
+
+    [encoder setFragmentBuffer: m_ubuf[stateInfo.currentFrameSlot] offset: 0 atIndex: 0];
+    [encoder setVertexBuffer: m_vbuf offset: 0 atIndex: 1];
+    [encoder setRenderPipelineState: m_pipeline];
+    [encoder drawPrimitives: MTLPrimitiveTypeTriangleStrip vertexStart: 0 vertexCount: 4 instanceCount: 1 baseInstance: 0];
+
+    m_window->endExternalCommands();
+}
+
+void SquircleRenderer::prepareShader(Stage stage)
+{
+    QString filename;
+    if (stage == VertexStage) {
+        filename = QLatin1String(":/scenegraph/metalunderqml/squircle.vert");
+    } else {
+        Q_ASSERT(stage == FragmentStage);
+        filename = QLatin1String(":/scenegraph/metalunderqml/squircle.frag");
+    }
+    QFile f(filename);
+    if (!f.open(QIODevice::ReadOnly))
+        qFatal("Failed to read shader %s", qPrintable(filename));
+
+    const QByteArray contents = f.readAll();
+
+    if (stage == VertexStage) {
+        m_vert = contents;
+        Q_ASSERT(!m_vert.isEmpty());
+        m_vertEntryPoint = QByteArrayLiteral("main0");
+    } else {
+        m_frag = contents;
+        Q_ASSERT(!m_frag.isEmpty());
+        m_fragEntryPoint = QByteArrayLiteral("main0");
+    }
+}
+
+SquircleRenderer::FuncAndLib SquircleRenderer::compileShaderFromSource(const QByteArray &src, const QByteArray &entryPoint)
+{
+    FuncAndLib fl;
+
+    NSString *srcstr = [NSString stringWithUTF8String: src.constData()];
+    MTLCompileOptions *opts = [[MTLCompileOptions alloc] init];
+    opts.languageVersion = MTLLanguageVersion1_2;
+    NSError *err = nil;
+    fl.second = [m_device newLibraryWithSource: srcstr options: opts error: &err];
+    [opts release];
+    // srcstr is autoreleased
+
+    if (err) {
+        const QString msg = QString::fromNSString(err.localizedDescription);
+        qFatal("%s", qPrintable(msg));
+        return fl;
+    }
+
+    NSString *name = [NSString stringWithUTF8String: entryPoint.constData()];
+    fl.first = [fl.second newFunctionWithName: name];
+    [name release];
+
+    return fl;
+}
+
+void SquircleRenderer::init(int framesInFlight)
+{
+    qDebug("init");
+
+    Q_ASSERT(framesInFlight <= 3);
+    m_initialized = true;
+
+    m_vbuf = [m_device newBufferWithLength: sizeof(vertices) options: MTLResourceStorageModeShared];
+    void *p = [m_vbuf contents];
+    memcpy(p, vertices, sizeof(vertices));
+
+    for (int i = 0; i < framesInFlight; ++i)
+        m_ubuf[i] = [m_device newBufferWithLength: UBUF_SIZE options: MTLResourceStorageModeShared];
+
+    MTLVertexDescriptor *inputLayout = [MTLVertexDescriptor vertexDescriptor];
+    inputLayout.attributes[0].format = MTLVertexFormatFloat2;
+    inputLayout.attributes[0].offset = 0;
+    inputLayout.attributes[0].bufferIndex = 1; // ubuf is 0, vbuf is 1
+    inputLayout.layouts[1].stride = 2 * sizeof(float);
+
+    MTLRenderPipelineDescriptor *rpDesc = [[MTLRenderPipelineDescriptor alloc] init];
+    rpDesc.vertexDescriptor = inputLayout;
+
+    m_vs = compileShaderFromSource(m_vert, m_vertEntryPoint);
+    rpDesc.vertexFunction = m_vs.first;
+    m_fs = compileShaderFromSource(m_frag, m_fragEntryPoint);
+    rpDesc.fragmentFunction = m_fs.first;
+
+    rpDesc.colorAttachments[0].pixelFormat = MTLPixelFormatBGRA8Unorm;
+    rpDesc.colorAttachments[0].blendingEnabled = true;
+    rpDesc.colorAttachments[0].sourceRGBBlendFactor = MTLBlendFactorSourceAlpha;
+    rpDesc.colorAttachments[0].sourceAlphaBlendFactor = MTLBlendFactorSourceAlpha;
+    rpDesc.colorAttachments[0].destinationRGBBlendFactor = MTLBlendFactorOne;
+    rpDesc.colorAttachments[0].destinationAlphaBlendFactor = MTLBlendFactorOne;
+
+    if (m_device.depth24Stencil8PixelFormatSupported) {
+        rpDesc.depthAttachmentPixelFormat = MTLPixelFormatDepth24Unorm_Stencil8;
+        rpDesc.stencilAttachmentPixelFormat = MTLPixelFormatDepth24Unorm_Stencil8;
+    } else {
+        rpDesc.depthAttachmentPixelFormat = MTLPixelFormatDepth32Float_Stencil8;
+        rpDesc.stencilAttachmentPixelFormat = MTLPixelFormatDepth32Float_Stencil8;
+    }
+
+    NSError *err = nil;
+    m_pipeline = [m_device newRenderPipelineStateWithDescriptor: rpDesc error: &err];
+    if (!m_pipeline) {
+        const QString msg = QString::fromNSString(err.localizedDescription);
+        qFatal("Failed to create render pipeline state: %s", qPrintable(msg));
+    }
+    [rpDesc release];
+}
+
+#include "metalsquircle.moc"
diff --git a/examples/quick/scenegraph/metalunderqml/metalunderqml.pro b/examples/quick/scenegraph/metalunderqml/metalunderqml.pro
new file mode 100644
index 0000000000..9fd131fe1b
--- /dev/null
+++ b/examples/quick/scenegraph/metalunderqml/metalunderqml.pro
@@ -0,0 +1,12 @@
+!macos: error("This example requires macOS")
+
+QT += qml quick
+
+HEADERS += metalsquircle.h
+SOURCES += metalsquircle.mm main.cpp
+RESOURCES += metalunderqml.qrc
+
+LIBS += -framework Metal -framework AppKit
+
+target.path = $$[QT_INSTALL_EXAMPLES]/quick/scenegraph/metalunderqml
+INSTALLS += target
diff --git a/examples/quick/scenegraph/metalunderqml/metalunderqml.qrc b/examples/quick/scenegraph/metalunderqml/metalunderqml.qrc
new file mode 100644
index 0000000000..7172f1fcb7
--- /dev/null
+++ b/examples/quick/scenegraph/metalunderqml/metalunderqml.qrc
@@ -0,0 +1,7 @@
+<RCC>
+    <qresource prefix="/scenegraph/metalunderqml">
+        <file>main.qml</file>
+        <file>squircle.vert</file>
+        <file>squircle.frag</file>
+    </qresource>
+</RCC>
diff --git a/examples/quick/scenegraph/metalunderqml/squircle.frag b/examples/quick/scenegraph/metalunderqml/squircle.frag
new file mode 100644
index 0000000000..15f34624fe
--- /dev/null
+++ b/examples/quick/scenegraph/metalunderqml/squircle.frag
@@ -0,0 +1,29 @@
+#include <metal_stdlib>
+#include <simd/simd.h>
+
+using namespace metal;
+
+struct buf
+{
+    float t;
+};
+
+struct main0_out
+{
+    float4 fragColor [[color(0)]];
+};
+
+struct main0_in
+{
+    float2 coords [[user(locn0)]];
+};
+
+fragment main0_out main0(main0_in in [[stage_in]], constant buf& ubuf [[buffer(0)]])
+{
+    main0_out out = {};
+    float i = 1.0 - (pow(abs(in.coords.x), 4.0) + pow(abs(in.coords.y), 4.0));
+    i = smoothstep(ubuf.t - 0.800000011920928955078125, ubuf.t + 0.800000011920928955078125, i);
+    i = floor(i * 20.0) / 20.0;
+    out.fragColor = float4((in.coords * 0.5) + float2(0.5), i, i);
+    return out;
+}
diff --git a/examples/quick/scenegraph/metalunderqml/squircle.vert b/examples/quick/scenegraph/metalunderqml/squircle.vert
new file mode 100644
index 0000000000..a88c59f541
--- /dev/null
+++ b/examples/quick/scenegraph/metalunderqml/squircle.vert
@@ -0,0 +1,23 @@
+#include <metal_stdlib>
+#include <simd/simd.h>
+
+using namespace metal;
+
+struct main0_out
+{
+    float2 coords [[user(locn0)]];
+    float4 gl_Position [[position]];
+};
+
+struct main0_in
+{
+    float4 vertices [[attribute(0)]];
+};
+
+vertex main0_out main0(main0_in in [[stage_in]])
+{
+    main0_out out = {};
+    out.gl_Position = in.vertices;
+    out.coords = in.vertices.xy;
+    return out;
+}