qt 6.6.0 clean

examples/gui/rhiwindow/CMakeLists.txt

@@ -0,0 +1,59 @@
+# Copyright (C) 2023 The Qt Company Ltd.
+# SPDX-License-Identifier: BSD-3-Clause
+
+cmake_minimum_required(VERSION 3.16)
+project(rhiwindow LANGUAGES CXX)
+
+if(NOT DEFINED INSTALL_EXAMPLESDIR)
+    set(INSTALL_EXAMPLESDIR "examples")
+endif()
+
+set(INSTALL_EXAMPLEDIR "${INSTALL_EXAMPLESDIR}/gui/rhiwindow")
+
+find_package(Qt6 REQUIRED COMPONENTS Core Gui)
+
+qt_standard_project_setup()
+
+qt_add_executable(rhiwindow
+    main.cpp
+    rhiwindow.cpp rhiwindow.h
+)
+
+set_target_properties(rhiwindow PROPERTIES
+    WIN32_EXECUTABLE TRUE
+    MACOSX_BUNDLE TRUE
+)
+
+target_link_libraries(rhiwindow PRIVATE
+    Qt6::Core
+    Qt6::Gui
+    Qt6::GuiPrivate
+)
+
+set_source_files_properties("shaders/prebuilt/color.vert.qsb"
+    PROPERTIES QT_RESOURCE_ALIAS "color.vert.qsb"
+)
+set_source_files_properties("shaders/prebuilt/color.frag.qsb"
+    PROPERTIES QT_RESOURCE_ALIAS "color.frag.qsb"
+)
+set_source_files_properties("shaders/prebuilt/quad.vert.qsb"
+    PROPERTIES QT_RESOURCE_ALIAS "quad.vert.qsb"
+)
+set_source_files_properties("shaders/prebuilt/quad.frag.qsb"
+    PROPERTIES QT_RESOURCE_ALIAS "quad.frag.qsb"
+)
+qt_add_resources(rhiwindow "rhiwindow"
+    PREFIX
+        "/"
+    FILES
+        "shaders/prebuilt/color.vert.qsb"
+        "shaders/prebuilt/color.frag.qsb"
+        "shaders/prebuilt/quad.vert.qsb"
+        "shaders/prebuilt/quad.frag.qsb"
+)
+
+install(TARGETS rhiwindow
+    RUNTIME DESTINATION "${INSTALL_EXAMPLEDIR}"
+    BUNDLE DESTINATION "${INSTALL_EXAMPLEDIR}"
+    LIBRARY DESTINATION "${INSTALL_EXAMPLEDIR}"
+)

examples/gui/rhiwindow/main.cpp

@@ -0,0 +1,110 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#include <QGuiApplication>
+#include <QCommandLineParser>
+#include "rhiwindow.h"
+
+int main(int argc, char **argv)
+{
+    QGuiApplication app(argc, argv);
+
+    QRhi::Implementation graphicsApi;
+
+    // Use platform-specific defaults when no command-line arguments given.
+#if defined(Q_OS_WIN)
+    graphicsApi = QRhi::D3D11;
+#elif defined(Q_OS_MACOS) || defined(Q_OS_IOS)
+    graphicsApi = QRhi::Metal;
+#elif QT_CONFIG(vulkan)
+    graphicsApi = QRhi::Vulkan;
+#else
+    graphicsApi = QRhi::OpenGLES2;
+#endif
+
+    QCommandLineParser cmdLineParser;
+    cmdLineParser.addHelpOption();
+    QCommandLineOption nullOption({ "n", "null" }, QLatin1String("Null"));
+    cmdLineParser.addOption(nullOption);
+    QCommandLineOption glOption({ "g", "opengl" }, QLatin1String("OpenGL"));
+    cmdLineParser.addOption(glOption);
+    QCommandLineOption vkOption({ "v", "vulkan" }, QLatin1String("Vulkan"));
+    cmdLineParser.addOption(vkOption);
+    QCommandLineOption d3d11Option({ "d", "d3d11" }, QLatin1String("Direct3D 11"));
+    cmdLineParser.addOption(d3d11Option);
+    QCommandLineOption d3d12Option({ "D", "d3d12" }, QLatin1String("Direct3D 12"));
+    cmdLineParser.addOption(d3d12Option);
+    QCommandLineOption mtlOption({ "m", "metal" }, QLatin1String("Metal"));
+    cmdLineParser.addOption(mtlOption);
+
+    cmdLineParser.process(app);
+    if (cmdLineParser.isSet(nullOption))
+        graphicsApi = QRhi::Null;
+    if (cmdLineParser.isSet(glOption))
+        graphicsApi = QRhi::OpenGLES2;
+    if (cmdLineParser.isSet(vkOption))
+        graphicsApi = QRhi::Vulkan;
+    if (cmdLineParser.isSet(d3d11Option))
+        graphicsApi = QRhi::D3D11;
+    if (cmdLineParser.isSet(d3d12Option))
+        graphicsApi = QRhi::D3D12;
+    if (cmdLineParser.isSet(mtlOption))
+        graphicsApi = QRhi::Metal;
+
+ //! [api-setup]
+    // For OpenGL, to ensure there is a depth/stencil buffer for the window.
+    // With other APIs this is under the application's control (QRhiRenderBuffer etc.)
+    // and so no special setup is needed for those.
+    QSurfaceFormat fmt;
+    fmt.setDepthBufferSize(24);
+    fmt.setStencilBufferSize(8);
+    // Special case macOS to allow using OpenGL there.
+    // (the default Metal is the recommended approach, though)
+    // gl_VertexID is a GLSL 130 feature, and so the default OpenGL 2.1 context
+    // we get on macOS is not sufficient.
+#ifdef Q_OS_MACOS
+    fmt.setVersion(4, 1);
+    fmt.setProfile(QSurfaceFormat::CoreProfile);
+#endif
+    QSurfaceFormat::setDefaultFormat(fmt);
+
+    // For Vulkan.
+#if QT_CONFIG(vulkan)
+    QVulkanInstance inst;
+    if (graphicsApi == QRhi::Vulkan) {
+        // Request validation, if available. This is completely optional
+        // and has a performance impact, and should be avoided in production use.
+        inst.setLayers({ "VK_LAYER_KHRONOS_validation" });
+        // Play nice with QRhi.
+        inst.setExtensions(QRhiVulkanInitParams::preferredInstanceExtensions());
+        if (!inst.create()) {
+            qWarning("Failed to create Vulkan instance, switching to OpenGL");
+            graphicsApi = QRhi::OpenGLES2;
+        }
+    }
+#endif
+//! [api-setup]
+
+    HelloWindow window(graphicsApi);
+
+#if QT_CONFIG(vulkan)
+    if (graphicsApi == QRhi::Vulkan)
+        window.setVulkanInstance(&inst);
+#endif
+    window.resize(1280, 720);
+    window.setTitle(QCoreApplication::applicationName() + QLatin1String(" - ") + window.graphicsApiName());
+    window.show();
+
+    int ret = app.exec();
+
+    // RhiWindow::event() will not get invoked when the
+    // PlatformSurfaceAboutToBeDestroyed event is sent during the QWindow
+    // destruction. That happens only when exiting via app::quit() instead of
+    // the more common QWindow::close(). Take care of it: if the QPlatformWindow
+    // is still around (there was no close() yet), get rid of the swapchain
+    // while it's not too late.
+    if (window.handle())
+        window.releaseSwapChain();
+
+    return ret;
+}

examples/gui/rhiwindow/rhiwindow.cpp

@@ -0,0 +1,435 @@
+// Copyright (C) 2020 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#include "rhiwindow.h"
+#include <QPlatformSurfaceEvent>
+#include <QPainter>
+#include <QFile>
+#include <rhi/qshader.h>
+
+//! [rhiwindow-ctor]
+RhiWindow::RhiWindow(QRhi::Implementation graphicsApi)
+    : m_graphicsApi(graphicsApi)
+{
+    switch (graphicsApi) {
+    case QRhi::OpenGLES2:
+        setSurfaceType(OpenGLSurface);
+        break;
+    case QRhi::Vulkan:
+        setSurfaceType(VulkanSurface);
+        break;
+    case QRhi::D3D11:
+    case QRhi::D3D12:
+        setSurfaceType(Direct3DSurface);
+        break;
+    case QRhi::Metal:
+        setSurfaceType(MetalSurface);
+        break;
+    case QRhi::Null:
+        break; // RasterSurface
+    }
+}
+//! [rhiwindow-ctor]
+
+QString RhiWindow::graphicsApiName() const
+{
+    switch (m_graphicsApi) {
+    case QRhi::Null:
+        return QLatin1String("Null (no output)");
+    case QRhi::OpenGLES2:
+        return QLatin1String("OpenGL");
+    case QRhi::Vulkan:
+        return QLatin1String("Vulkan");
+    case QRhi::D3D11:
+        return QLatin1String("Direct3D 11");
+    case QRhi::D3D12:
+        return QLatin1String("Direct3D 12");
+    case QRhi::Metal:
+        return QLatin1String("Metal");
+    }
+    return QString();
+}
+
+//! [expose]
+void RhiWindow::exposeEvent(QExposeEvent *)
+{
+    // initialize and start rendering when the window becomes usable for graphics purposes
+    if (isExposed() && !m_initialized) {
+        init();
+        resizeSwapChain();
+        m_initialized = true;
+    }
+
+    const QSize surfaceSize = m_hasSwapChain ? m_sc->surfacePixelSize() : QSize();
+
+    // stop pushing frames when not exposed (or size is 0)
+    if ((!isExposed() || (m_hasSwapChain && surfaceSize.isEmpty())) && m_initialized && !m_notExposed)
+        m_notExposed = true;
+
+    // Continue when exposed again and the surface has a valid size. Note that
+    // surfaceSize can be (0, 0) even though size() reports a valid one, hence
+    // trusting surfacePixelSize() and not QWindow.
+    if (isExposed() && m_initialized && m_notExposed && !surfaceSize.isEmpty()) {
+        m_notExposed = false;
+        m_newlyExposed = true;
+    }
+
+    // always render a frame on exposeEvent() (when exposed) in order to update
+    // immediately on window resize.
+    if (isExposed() && !surfaceSize.isEmpty())
+        render();
+}
+//! [expose]
+
+//! [event]
+bool RhiWindow::event(QEvent *e)
+{
+    switch (e->type()) {
+    case QEvent::UpdateRequest:
+        render();
+        break;
+
+    case QEvent::PlatformSurface:
+        // this is the proper time to tear down the swapchain (while the native window and surface are still around)
+        if (static_cast<QPlatformSurfaceEvent *>(e)->surfaceEventType() == QPlatformSurfaceEvent::SurfaceAboutToBeDestroyed)
+            releaseSwapChain();
+        break;
+
+    default:
+        break;
+    }
+
+    return QWindow::event(e);
+}
+//! [event]
+
+//! [rhi-init]
+void RhiWindow::init()
+{
+    if (m_graphicsApi == QRhi::Null) {
+        QRhiNullInitParams params;
+        m_rhi.reset(QRhi::create(QRhi::Null, &params));
+    }
+
+#if QT_CONFIG(opengl)
+    if (m_graphicsApi == QRhi::OpenGLES2) {
+        m_fallbackSurface.reset(QRhiGles2InitParams::newFallbackSurface());
+        QRhiGles2InitParams params;
+        params.fallbackSurface = m_fallbackSurface.get();
+        params.window = this;
+        m_rhi.reset(QRhi::create(QRhi::OpenGLES2, &params));
+    }
+#endif
+
+#if QT_CONFIG(vulkan)
+    if (m_graphicsApi == QRhi::Vulkan) {
+        QRhiVulkanInitParams params;
+        params.inst = vulkanInstance();
+        params.window = this;
+        m_rhi.reset(QRhi::create(QRhi::Vulkan, &params));
+    }
+#endif
+
+#ifdef Q_OS_WIN
+    if (m_graphicsApi == QRhi::D3D11) {
+        QRhiD3D11InitParams params;
+        // Enable the debug layer, if available. This is optional
+        // and should be avoided in production builds.
+        params.enableDebugLayer = true;
+        m_rhi.reset(QRhi::create(QRhi::D3D11, &params));
+    } else if (m_graphicsApi == QRhi::D3D12) {
+        QRhiD3D12InitParams params;
+        // Enable the debug layer, if available. This is optional
+        // and should be avoided in production builds.
+        params.enableDebugLayer = true;
+        m_rhi.reset(QRhi::create(QRhi::D3D12, &params));
+    }
+#endif
+
+#if defined(Q_OS_MACOS) || defined(Q_OS_IOS)
+    if (m_graphicsApi == QRhi::Metal) {
+        QRhiMetalInitParams params;
+        m_rhi.reset(QRhi::create(QRhi::Metal, &params));
+    }
+#endif
+
+    if (!m_rhi)
+        qFatal("Failed to create RHI backend");
+//! [rhi-init]
+
+//! [swapchain-init]
+    m_sc.reset(m_rhi->newSwapChain());
+    m_ds.reset(m_rhi->newRenderBuffer(QRhiRenderBuffer::DepthStencil,
+                                      QSize(), // no need to set the size here, due to UsedWithSwapChainOnly
+                                      1,
+                                      QRhiRenderBuffer::UsedWithSwapChainOnly));
+    m_sc->setWindow(this);
+    m_sc->setDepthStencil(m_ds.get());
+    m_rp.reset(m_sc->newCompatibleRenderPassDescriptor());
+    m_sc->setRenderPassDescriptor(m_rp.get());
+//! [swapchain-init]
+
+    customInit();
+}
+
+//! [swapchain-resize]
+void RhiWindow::resizeSwapChain()
+{
+    m_hasSwapChain = m_sc->createOrResize(); // also handles m_ds
+
+    const QSize outputSize = m_sc->currentPixelSize();
+    m_viewProjection = m_rhi->clipSpaceCorrMatrix();
+    m_viewProjection.perspective(45.0f, outputSize.width() / (float) outputSize.height(), 0.01f, 1000.0f);
+    m_viewProjection.translate(0, 0, -4);
+}
+//! [swapchain-resize]
+
+void RhiWindow::releaseSwapChain()
+{
+    if (m_hasSwapChain) {
+        m_hasSwapChain = false;
+        m_sc->destroy();
+    }
+}
+
+//! [render-precheck]
+void RhiWindow::render()
+{
+    if (!m_hasSwapChain || m_notExposed)
+        return;
+//! [render-precheck]
+
+//! [render-resize]
+    // If the window got resized or newly exposed, resize the swapchain. (the
+    // newly-exposed case is not actually required by some platforms, but is
+    // here for robustness and portability)
+    //
+    // This (exposeEvent + the logic here) is the only safe way to perform
+    // resize handling. Note the usage of the RHI's surfacePixelSize(), and
+    // never QWindow::size(). (the two may or may not be the same under the hood,
+    // depending on the backend and platform)
+    //
+    if (m_sc->currentPixelSize() != m_sc->surfacePixelSize() || m_newlyExposed) {
+        resizeSwapChain();
+        if (!m_hasSwapChain)
+            return;
+        m_newlyExposed = false;
+    }
+//! [render-resize]
+
+//! [beginframe]
+    QRhi::FrameOpResult result = m_rhi->beginFrame(m_sc.get());
+    if (result == QRhi::FrameOpSwapChainOutOfDate) {
+        resizeSwapChain();
+        if (!m_hasSwapChain)
+            return;
+        result = m_rhi->beginFrame(m_sc.get());
+    }
+    if (result != QRhi::FrameOpSuccess) {
+        qWarning("beginFrame failed with %d, will retry", result);
+        requestUpdate();
+        return;
+    }
+
+    customRender();
+//! [beginframe]
+
+//! [request-update]
+    m_rhi->endFrame(m_sc.get());
+
+    // Always request the next frame via requestUpdate(). On some platforms this is backed
+    // by a platform-specific solution, e.g. CVDisplayLink on macOS, which is potentially
+    // more efficient than a timer, queued metacalls, etc.
+    requestUpdate();
+}
+//! [request-update]
+
+static float vertexData[] = {
+    // Y up (note clipSpaceCorrMatrix in m_viewProjection), CCW
+     0.0f,   0.5f,   1.0f, 0.0f, 0.0f,
+    -0.5f,  -0.5f,   0.0f, 1.0f, 0.0f,
+     0.5f,  -0.5f,   0.0f, 0.0f, 1.0f,
+};
+
+//! [getshader]
+static QShader getShader(const QString &name)
+{
+    QFile f(name);
+    if (f.open(QIODevice::ReadOnly))
+        return QShader::fromSerialized(f.readAll());
+
+    return QShader();
+}
+//! [getshader]
+
+HelloWindow::HelloWindow(QRhi::Implementation graphicsApi)
+    : RhiWindow(graphicsApi)
+{
+}
+
+//! [ensure-texture]
+void HelloWindow::ensureFullscreenTexture(const QSize &pixelSize, QRhiResourceUpdateBatch *u)
+{
+    if (m_texture && m_texture->pixelSize() == pixelSize)
+        return;
+
+    if (!m_texture)
+        m_texture.reset(m_rhi->newTexture(QRhiTexture::RGBA8, pixelSize));
+    else
+        m_texture->setPixelSize(pixelSize);
+
+    m_texture->create();
+
+    QImage image(pixelSize, QImage::Format_RGBA8888_Premultiplied);
+//! [ensure-texture]
+    QPainter painter(&image);
+    painter.fillRect(QRectF(QPointF(0, 0), pixelSize), QColor::fromRgbF(0.4f, 0.7f, 0.0f, 1.0f));
+    painter.setPen(Qt::transparent);
+    painter.setBrush({ QGradient(QGradient::DeepBlue) });
+    painter.drawRoundedRect(QRectF(QPointF(20, 20), pixelSize - QSize(40, 40)), 16, 16);
+    painter.setPen(Qt::black);
+    QFont font;
+    font.setPixelSize(0.05 * qMin(pixelSize.width(), pixelSize.height()));
+    painter.setFont(font);
+    painter.drawText(QRectF(QPointF(60, 60), pixelSize - QSize(120, 120)), 0,
+                     QLatin1String("Rendering with QRhi to a resizable QWindow.\nThe 3D API is %1.\nUse the command-line options to choose a different API.")
+                     .arg(graphicsApiName()));
+    painter.end();
+
+    if (m_rhi->isYUpInNDC())
+        image = image.mirrored();
+
+//! [ensure-texture-2]
+    u->uploadTexture(m_texture.get(), image);
+//! [ensure-texture-2]
+}
+
+//! [render-init-1]
+void HelloWindow::customInit()
+{
+    m_initialUpdates = m_rhi->nextResourceUpdateBatch();
+
+    m_vbuf.reset(m_rhi->newBuffer(QRhiBuffer::Immutable, QRhiBuffer::VertexBuffer, sizeof(vertexData)));
+    m_vbuf->create();
+    m_initialUpdates->uploadStaticBuffer(m_vbuf.get(), vertexData);
+
+    static const quint32 UBUF_SIZE = 68;
+    m_ubuf.reset(m_rhi->newBuffer(QRhiBuffer::Dynamic, QRhiBuffer::UniformBuffer, UBUF_SIZE));
+    m_ubuf->create();
+//! [render-init-1]
+
+    ensureFullscreenTexture(m_sc->surfacePixelSize(), m_initialUpdates);
+
+    m_sampler.reset(m_rhi->newSampler(QRhiSampler::Linear, QRhiSampler::Linear, QRhiSampler::None,
+                                      QRhiSampler::ClampToEdge, QRhiSampler::ClampToEdge));
+    m_sampler->create();
+
+ //! [render-init-2]
+    m_colorTriSrb.reset(m_rhi->newShaderResourceBindings());
+    static const QRhiShaderResourceBinding::StageFlags visibility =
+            QRhiShaderResourceBinding::VertexStage | QRhiShaderResourceBinding::FragmentStage;
+    m_colorTriSrb->setBindings({
+            QRhiShaderResourceBinding::uniformBuffer(0, visibility, m_ubuf.get())
+    });
+    m_colorTriSrb->create();
+
+    m_colorPipeline.reset(m_rhi->newGraphicsPipeline());
+    // Enable depth testing; not quite needed for a simple triangle, but we
+    // have a depth-stencil buffer so why not.
+    m_colorPipeline->setDepthTest(true);
+    m_colorPipeline->setDepthWrite(true);
+    // Blend factors default to One, OneOneMinusSrcAlpha, which is convenient.
+    QRhiGraphicsPipeline::TargetBlend premulAlphaBlend;
+    premulAlphaBlend.enable = true;
+    m_colorPipeline->setTargetBlends({ premulAlphaBlend });
+    m_colorPipeline->setShaderStages({
+        { QRhiShaderStage::Vertex, getShader(QLatin1String(":/color.vert.qsb")) },
+        { QRhiShaderStage::Fragment, getShader(QLatin1String(":/color.frag.qsb")) }
+    });
+    QRhiVertexInputLayout inputLayout;
+    inputLayout.setBindings({
+        { 5 * sizeof(float) }
+    });
+    inputLayout.setAttributes({
+        { 0, 0, QRhiVertexInputAttribute::Float2, 0 },
+        { 0, 1, QRhiVertexInputAttribute::Float3, 2 * sizeof(float) }
+    });
+    m_colorPipeline->setVertexInputLayout(inputLayout);
+    m_colorPipeline->setShaderResourceBindings(m_colorTriSrb.get());
+    m_colorPipeline->setRenderPassDescriptor(m_rp.get());
+    m_colorPipeline->create();
+//! [render-init-2]
+
+    m_fullscreenQuadSrb.reset(m_rhi->newShaderResourceBindings());
+    m_fullscreenQuadSrb->setBindings({
+            QRhiShaderResourceBinding::sampledTexture(0, QRhiShaderResourceBinding::FragmentStage,
+                                       m_texture.get(), m_sampler.get())
+    });
+    m_fullscreenQuadSrb->create();
+
+    m_fullscreenQuadPipeline.reset(m_rhi->newGraphicsPipeline());
+    m_fullscreenQuadPipeline->setShaderStages({
+        { QRhiShaderStage::Vertex, getShader(QLatin1String(":/quad.vert.qsb")) },
+        { QRhiShaderStage::Fragment, getShader(QLatin1String(":/quad.frag.qsb")) }
+    });
+    m_fullscreenQuadPipeline->setVertexInputLayout({});
+    m_fullscreenQuadPipeline->setShaderResourceBindings(m_fullscreenQuadSrb.get());
+    m_fullscreenQuadPipeline->setRenderPassDescriptor(m_rp.get());
+    m_fullscreenQuadPipeline->create();
+}
+
+//! [render-1]
+void HelloWindow::customRender()
+{
+    QRhiResourceUpdateBatch *resourceUpdates = m_rhi->nextResourceUpdateBatch();
+
+    if (m_initialUpdates) {
+        resourceUpdates->merge(m_initialUpdates);
+        m_initialUpdates->release();
+        m_initialUpdates = nullptr;
+    }
+//! [render-1]
+
+//! [render-rotation]
+    m_rotation += 1.0f;
+    QMatrix4x4 modelViewProjection = m_viewProjection;
+    modelViewProjection.rotate(m_rotation, 0, 1, 0);
+    resourceUpdates->updateDynamicBuffer(m_ubuf.get(), 0, 64, modelViewProjection.constData());
+//! [render-rotation]
+
+//! [render-opacity]
+    m_opacity += m_opacityDir * 0.005f;
+    if (m_opacity < 0.0f || m_opacity > 1.0f) {
+        m_opacityDir *= -1;
+        m_opacity = qBound(0.0f, m_opacity, 1.0f);
+    }
+    resourceUpdates->updateDynamicBuffer(m_ubuf.get(), 64, 4, &m_opacity);
+//! [render-opacity]
+
+//! [render-cb]
+    QRhiCommandBuffer *cb = m_sc->currentFrameCommandBuffer();
+    const QSize outputSizeInPixels = m_sc->currentPixelSize();
+//! [render-cb]
+
+    // (re)create the texture with a size matching the output surface size, when necessary.
+    ensureFullscreenTexture(outputSizeInPixels, resourceUpdates);
+
+//! [render-pass]
+    cb->beginPass(m_sc->currentFrameRenderTarget(), Qt::black, { 1.0f, 0 }, resourceUpdates);
+//! [render-pass]
+
+    cb->setGraphicsPipeline(m_fullscreenQuadPipeline.get());
+    cb->setViewport({ 0, 0, float(outputSizeInPixels.width()), float(outputSizeInPixels.height()) });
+    cb->setShaderResources();
+    cb->draw(3);
+
+//! [render-pass-record]
+    cb->setGraphicsPipeline(m_colorPipeline.get());
+    cb->setShaderResources();
+    const QRhiCommandBuffer::VertexInput vbufBinding(m_vbuf.get(), 0);
+    cb->setVertexInput(0, 1, &vbufBinding);
+    cb->draw(3);
+
+    cb->endPass();
+//! [render-pass-record]
+}

examples/gui/rhiwindow/rhiwindow.h

@@ -0,0 +1,78 @@
+// Copyright (C) 2020 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#ifndef WINDOW_H
+#define WINDOW_H
+
+#include <QWindow>
+#include <QOffscreenSurface>
+#include <rhi/qrhi.h>
+
+class RhiWindow : public QWindow
+{
+public:
+    RhiWindow(QRhi::Implementation graphicsApi);
+    QString graphicsApiName() const;
+    void releaseSwapChain();
+
+protected:
+    virtual void customInit() = 0;
+    virtual void customRender() = 0;
+
+    // destruction order matters to a certain degree: the fallbackSurface must
+    // outlive the rhi, the rhi must outlive all other resources.  The resources
+    // need no special order when destroying.
+#if QT_CONFIG(opengl)
+    std::unique_ptr<QOffscreenSurface> m_fallbackSurface;
+#endif
+    std::unique_ptr<QRhi> m_rhi;
+//! [swapchain-data]
+    std::unique_ptr<QRhiSwapChain> m_sc;
+    std::unique_ptr<QRhiRenderBuffer> m_ds;
+    std::unique_ptr<QRhiRenderPassDescriptor> m_rp;
+//! [swapchain-data]
+    bool m_hasSwapChain = false;
+    QMatrix4x4 m_viewProjection;
+
+private:
+    void init();
+    void resizeSwapChain();
+    void render();
+
+    void exposeEvent(QExposeEvent *) override;
+    bool event(QEvent *) override;
+
+    QRhi::Implementation m_graphicsApi;
+    bool m_initialized = false;
+    bool m_notExposed = false;
+    bool m_newlyExposed = false;
+};
+
+class HelloWindow : public RhiWindow
+{
+public:
+    HelloWindow(QRhi::Implementation graphicsApi);
+
+    void customInit() override;
+    void customRender() override;
+
+private:
+    void ensureFullscreenTexture(const QSize &pixelSize, QRhiResourceUpdateBatch *u);
+
+    std::unique_ptr<QRhiBuffer> m_vbuf;
+    std::unique_ptr<QRhiBuffer> m_ubuf;
+    std::unique_ptr<QRhiTexture> m_texture;
+    std::unique_ptr<QRhiSampler> m_sampler;
+    std::unique_ptr<QRhiShaderResourceBindings> m_colorTriSrb;
+    std::unique_ptr<QRhiGraphicsPipeline> m_colorPipeline;
+    std::unique_ptr<QRhiShaderResourceBindings> m_fullscreenQuadSrb;
+    std::unique_ptr<QRhiGraphicsPipeline> m_fullscreenQuadPipeline;
+
+    QRhiResourceUpdateBatch *m_initialUpdates = nullptr;
+
+    float m_rotation = 0;
+    float m_opacity = 1;
+    int m_opacityDir = -1;
+};
+
+#endif

examples/gui/rhiwindow/rhiwindow.pri

@@ -0,0 +1,4 @@
+INCLUDEPATH += $$PWD
+SOURCES += $$PWD/rhiwindow.cpp
+HEADERS += $$PWD/rhiwindow.h
+RESOURCES += $$PWD/rhiwindow.qrc

examples/gui/rhiwindow/rhiwindow.pro

@@ -0,0 +1,9 @@
+include(rhiwindow.pri)
+
+QT += gui-private
+
+SOURCES += \
+    main.cpp
+
+target.path = $$[QT_INSTALL_EXAMPLES]/gui/rhiwindow
+INSTALLS += target

examples/gui/rhiwindow/rhiwindow.qrc

@@ -0,0 +1,8 @@
+<!DOCTYPE RCC><RCC version="1.0">
+<qresource>
+  <file alias="color.vert.qsb">shaders/prebuilt/color.vert.qsb</file>
+  <file alias="color.frag.qsb">shaders/prebuilt/color.frag.qsb</file>
+  <file alias="quad.vert.qsb">shaders/prebuilt/quad.vert.qsb</file>
+  <file alias="quad.frag.qsb">shaders/prebuilt/quad.frag.qsb</file>
+</qresource>
+</RCC>

examples/gui/rhiwindow/shaders/color.frag

@@ -0,0 +1,15 @@
+#version 440
+
+layout(location = 0) in vec3 v_color;
+
+layout(location = 0) out vec4 fragColor;
+
+layout(std140, binding = 0) uniform buf {
+    mat4 mvp;
+    float opacity;
+};
+
+void main()
+{
+    fragColor = vec4(v_color * opacity, opacity);
+}

examples/gui/rhiwindow/shaders/color.vert

@@ -0,0 +1,17 @@
+#version 440
+
+layout(location = 0) in vec4 position;
+layout(location = 1) in vec3 color;
+
+layout(location = 0) out vec3 v_color;
+
+layout(std140, binding = 0) uniform buf {
+    mat4 mvp;
+    float opacity;
+};
+
+void main()
+{
+    v_color = color;
+    gl_Position = mvp * position;
+}

examples/gui/rhiwindow/shaders/quad.frag

@@ -0,0 +1,11 @@
+#version 440
+
+layout(location = 0) in vec2 v_uv;
+layout(location = 0) out vec4 fragColor;
+layout(binding = 0) uniform sampler2D tex;
+
+void main()
+{
+    vec4 c = texture(tex, v_uv);
+    fragColor = vec4(c.rgb * c.a, c.a);
+}

examples/gui/rhiwindow/shaders/quad.vert

@@ -0,0 +1,10 @@
+#version 440
+
+layout (location = 0) out vec2 v_uv;
+
+void main()
+{
+    // https://www.saschawillems.de/blog/2016/08/13/vulkan-tutorial-on-rendering-a-fullscreen-quad-without-buffers/
+    v_uv = vec2((gl_VertexIndex << 1) & 2, gl_VertexIndex & 2);
+    gl_Position = vec4(v_uv * 2.0 - 1.0, 0.0, 1.0);
+}