Remove threadeqopenglwidget example

It is neither documented nor very useful, and it has
platform-specific issues as reported over the years.

Remove it now as part of the example revamp initiative.

Task-number: QTBUG-50278
Task-number: QTBUG-110093
Task-number: QTBUG-76054
Task-number: QTBUG-43209
Pick-to: 6.5
Change-Id: I6dadaf4162b4c19411c544b9f204c19e37aa740d
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>

examples/opengl/CMakeLists.txt

@@ -7,7 +7,6 @@ qt_internal_add_example(openglwindow)
 qt_internal_add_example(qopenglwindow)
 if(TARGET Qt6::Widgets)
     qt_internal_add_example(contextinfo)
-    qt_internal_add_example(threadedqopenglwidget)
     qt_internal_add_example(2dpainting)
     qt_internal_add_example(hellogl2)
     qt_internal_add_example(qopenglwidget)

examples/opengl/opengl.pro

@@ -7,7 +7,6 @@ SUBDIRS = hellowindow \
 
 qtHaveModule(widgets) {
     SUBDIRS += contextinfo \
-               threadedqopenglwidget \
                2dpainting \
                hellogl2 \
                qopenglwidget \

examples/opengl/threadedqopenglwidget/CMakeLists.txt

@@ -1,41 +0,0 @@
-# Copyright (C) 2022 The Qt Company Ltd.
-# SPDX-License-Identifier: BSD-3-Clause
-
-cmake_minimum_required(VERSION 3.16)
-project(threadedqopenglwidget LANGUAGES CXX)
-
-if(NOT DEFINED INSTALL_EXAMPLESDIR)
-    set(INSTALL_EXAMPLESDIR "examples")
-endif()
-
-set(INSTALL_EXAMPLEDIR "${INSTALL_EXAMPLESDIR}/opengl/threadedqopenglwidget")
-
-find_package(Qt6 REQUIRED COMPONENTS Core Gui OpenGL OpenGLWidgets Widgets)
-
-qt_standard_project_setup()
-
-qt_add_executable(threadedqopenglwidget
-    renderer.cpp renderer.h
-    glwidget.cpp glwidget.h
-    main.cpp
-    mainwindow.cpp mainwindow.h
-)
-
-set_target_properties(threadedqopenglwidget PROPERTIES
-    WIN32_EXECUTABLE TRUE
-    MACOSX_BUNDLE TRUE
-)
-
-target_link_libraries(threadedqopenglwidget PRIVATE
-    Qt6::Core
-    Qt6::Gui
-    Qt6::OpenGL
-    Qt6::OpenGLWidgets
-    Qt6::Widgets
-)
-
-install(TARGETS threadedqopenglwidget
-    RUNTIME DESTINATION "${INSTALL_EXAMPLEDIR}"
-    BUNDLE DESTINATION "${INSTALL_EXAMPLEDIR}"
-    LIBRARY DESTINATION "${INSTALL_EXAMPLEDIR}"
-)

examples/opengl/threadedqopenglwidget/glwidget.cpp

@@ -1,71 +0,0 @@
-// Copyright (C) 2022 The Qt Company Ltd.
-// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
-
-#include "glwidget.h"
-#include "renderer.h"
-
-#include <qmath.h>
-#include <QGuiApplication>
-
-GLWidget::GLWidget(QWidget *parent)
-    : QOpenGLWidget(parent)
-{
-    setMinimumSize(300, 250);
-
-    connect(this, &QOpenGLWidget::aboutToCompose, this, &GLWidget::onAboutToCompose);
-    connect(this, &QOpenGLWidget::frameSwapped, this, &GLWidget::onFrameSwapped);
-    connect(this, &QOpenGLWidget::aboutToResize, this, &GLWidget::onAboutToResize);
-    connect(this, &QOpenGLWidget::resized, this, &GLWidget::onResized);
-
-    m_thread = new QThread;
-    m_renderer = new Renderer(this);
-    m_renderer->moveToThread(m_thread);
-    connect(m_thread, &QThread::finished, m_renderer, &QObject::deleteLater);
-
-    connect(this, &GLWidget::renderRequested, m_renderer, &Renderer::render);
-    connect(m_renderer, &Renderer::contextWanted, this, &GLWidget::grabContext);
-
-    m_thread->start();
-}
-
-GLWidget::~GLWidget()
-{
-    m_renderer->prepareExit();
-    m_thread->quit();
-    m_thread->wait();
-    delete m_thread;
-}
-
-void GLWidget::onAboutToCompose()
-{
-    // We are on the gui thread here. Composition is about to
-    // begin. Wait until the render thread finishes.
-    m_renderer->lockRenderer();
-}
-
-void GLWidget::onFrameSwapped()
-{
-    m_renderer->unlockRenderer();
-    // Assuming a blocking swap, our animation is driven purely by the
-    // vsync in this example.
-    emit renderRequested();
-}
-
-void GLWidget::onAboutToResize()
-{
-    m_renderer->lockRenderer();
-}
-
-void GLWidget::onResized()
-{
-    m_renderer->unlockRenderer();
-}
-
-void GLWidget::grabContext()
-{
-    m_renderer->lockRenderer();
-    QMutexLocker lock(m_renderer->grabMutex());
-    context()->moveToThread(m_thread);
-    m_renderer->grabCond()->wakeAll();
-    m_renderer->unlockRenderer();
-}

examples/opengl/threadedqopenglwidget/glwidget.h

@@ -1,40 +0,0 @@
-// Copyright (C) 2022 The Qt Company Ltd.
-// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
-
-#ifndef GLWIDGET_H
-#define GLWIDGET_H
-
-#include <QOpenGLWidget>
-
-QT_FORWARD_DECLARE_CLASS(QThread)
-
-class Renderer;
-
-class GLWidget : public QOpenGLWidget
-{
-    Q_OBJECT
-public:
-    explicit GLWidget(QWidget *parent = nullptr);
-    ~GLWidget();
-
-protected:
-    void paintEvent(QPaintEvent *) override { }
-
-signals:
-    void renderRequested();
-
-public slots:
-    void grabContext();
-
-private slots:
-    void onAboutToCompose();
-    void onFrameSwapped();
-    void onAboutToResize();
-    void onResized();
-
-private:
-    QThread *m_thread;
-    Renderer *m_renderer;
-};
-
-#endif // GLWIDGET_H

examples/opengl/threadedqopenglwidget/main.cpp

@@ -1,88 +0,0 @@
-// Copyright (C) 2022 The Qt Company Ltd.
-// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
-
-#include <QApplication>
-#include <QMainWindow>
-#include <QScreen>
-#include <QShortcut>
-#include <QSurfaceFormat>
-#include <QOpenGLContext>
-#include <QOpenGLFunctions>
-#include <QCommandLineParser>
-#include <QCommandLineOption>
-#include "mainwindow.h"
-#include "glwidget.h"
-
-#include <memory>
-
-static QString getGlString(QOpenGLFunctions *functions, GLenum name)
-{
-    if (const GLubyte *p = functions->glGetString(name))
-        return QString::fromLatin1(reinterpret_cast<const char *>(p));
-    return QString();
-}
-
-int main( int argc, char ** argv )
-{
-    QApplication a( argc, argv );
-
-    QCoreApplication::setApplicationName("Qt Threaded QOpenGLWidget Example");
-    QCoreApplication::setOrganizationName("QtProject");
-    QCoreApplication::setApplicationVersion(QT_VERSION_STR);
-    QCommandLineParser parser;
-    parser.setApplicationDescription(QCoreApplication::applicationName());
-    parser.addHelpOption();
-    parser.addVersionOption();
-    QCommandLineOption singleOption("single", "Single thread");
-    parser.addOption(singleOption);
-    parser.process(a);
-
-    QSurfaceFormat format;
-    format.setDepthBufferSize(16);
-    QSurfaceFormat::setDefaultFormat(format);
-
-    // Two top-level windows with two QOpenGLWidget children in each.
-    // The rendering for the four QOpenGLWidgets happens on four separate threads.
-
-    GLWidget topLevelGlWidget;
-    QPoint pos = topLevelGlWidget.screen()->availableGeometry().topLeft() + QPoint(200, 200);
-    topLevelGlWidget.setWindowTitle(QStringLiteral("Threaded QOpenGLWidget example top level"));
-    topLevelGlWidget.resize(200, 200);
-    topLevelGlWidget.move(pos);
-    topLevelGlWidget.show();
-    auto *closeShortcut = new QShortcut(Qt::CTRL | Qt::Key_Q, &a, QApplication::closeAllWindows);
-    closeShortcut->setContext(Qt::ApplicationShortcut);
-
-    const QString glInfo = getGlString(topLevelGlWidget.context()->functions(), GL_VENDOR)
-        + QLatin1Char('/') + getGlString(topLevelGlWidget.context()->functions(), GL_RENDERER);
-
-    const bool supportsThreading = !glInfo.contains(QLatin1String("nouveau"), Qt::CaseInsensitive)
-        && !glInfo.contains(QLatin1String("ANGLE"), Qt::CaseInsensitive)
-        && !glInfo.contains(QLatin1String("llvmpipe"), Qt::CaseInsensitive);
-
-    const QString toolTip = supportsThreading ? glInfo : glInfo + QStringLiteral("\ndoes not support threaded OpenGL.");
-    topLevelGlWidget.setToolTip(toolTip);
-
-    std::unique_ptr<MainWindow> mw1;
-    std::unique_ptr<MainWindow> mw2;
-    if (!parser.isSet(singleOption)) {
-        if (supportsThreading) {
-            pos += QPoint(100, 100);
-            mw1.reset(new MainWindow);
-            mw1->setToolTip(toolTip);
-            mw1->move(pos);
-            mw1->setWindowTitle(QStringLiteral("Threaded QOpenGLWidget example #1"));
-            mw1->show();
-            pos += QPoint(100, 100);
-            mw2.reset(new MainWindow);
-            mw2->setToolTip(toolTip);
-            mw2->move(pos);
-            mw2->setWindowTitle(QStringLiteral("Threaded QOpenGLWidget example #2"));
-            mw2->show();
-        } else {
-            qWarning() << toolTip;
-        }
-    }
-
-    return a.exec();
-}

examples/opengl/threadedqopenglwidget/mainwindow.cpp

@@ -1,16 +0,0 @@
-// Copyright (C) 2022 The Qt Company Ltd.
-// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
-
-#include "mainwindow.h"
-#include "glwidget.h"
-
-MainWindow::MainWindow()
-{
-    setMinimumSize(800, 400);
-    GLWidget *glwidget1 = new GLWidget(this);
-    glwidget1->resize(400, 400);
-
-    GLWidget *glwidget2 = new GLWidget(this);
-    glwidget2->resize(400, 400);
-    glwidget2->move(400, 0);
-}

examples/opengl/threadedqopenglwidget/mainwindow.h

@@ -1,17 +0,0 @@
-// Copyright (C) 2022 The Qt Company Ltd.
-// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
-
-#ifndef MAINWINDOW_H
-#define MAINWINDOW_H
-
-#include <QWidget>
-
-class MainWindow : public QWidget
-{
-    Q_OBJECT
-
-public:
-    MainWindow();
-};
-
-#endif

examples/opengl/threadedqopenglwidget/renderer.cpp

@@ -1,267 +0,0 @@
-// Copyright (C) 2022 The Qt Company Ltd.
-// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
-
-#include "renderer.h"
-#include <qmath.h>
-#include <QOpenGLWidget>
-#include <QGuiApplication>
-
-static const char VERTEX_SHADER[] = R"(attribute highp vec4 vertex;
-attribute mediump vec3 normal;
-uniform mediump mat4 matrix;
-varying mediump vec4 color;
-void main(void)
-{
-    vec3 toLight = normalize(vec3(0.0, 0.3, 1.0));
-    float angle = max(dot(normal, toLight), 0.0);
-    vec3 col = vec3(0.40, 1.0, 0.0);
-    color = vec4(col * 0.2 + col * 0.8 * angle, 1.0);
-    color = clamp(color, 0.0, 1.0);
-    gl_Position = matrix * vertex;
-}
-)";
-
-static const char FRAGMENT_SHADER[] = R"(varying mediump vec4 color;
-void main(void)
-{
-    gl_FragColor = color;
-}
-)";
-
-Renderer::Renderer(QOpenGLWidget *w) :
-    m_glwidget(w)
-{
-}
-
-void Renderer::paintQtLogo()
-{
-    vbo.bind();
-    program.setAttributeBuffer(vertexAttr, GL_FLOAT, 0, 3);
-    program.setAttributeBuffer(normalAttr, GL_FLOAT, vertices.count() * 3 * sizeof(GLfloat), 3);
-    vbo.release();
-
-    program.enableAttributeArray(vertexAttr);
-    program.enableAttributeArray(normalAttr);
-
-    glDrawArrays(GL_TRIANGLES, 0, vertices.size());
-
-    program.disableAttributeArray(normalAttr);
-    program.disableAttributeArray(vertexAttr);
-}
-
-// Some OpenGL implementations have serious issues with compiling and linking
-// shaders on multiple threads concurrently. Avoid this.
-Q_GLOBAL_STATIC(QMutex, initMutex)
-
-void Renderer::render()
-{
-    if (m_exiting)
-        return;
-
-    QOpenGLContext *ctx = m_glwidget->context();
-    if (!ctx) // QOpenGLWidget not yet initialized
-        return;
-
-    // Grab the context.
-    m_grabMutex.lock();
-    emit contextWanted();
-    m_grabCond.wait(&m_grabMutex);
-    QMutexLocker lock(&m_renderMutex);
-    m_grabMutex.unlock();
-
-    if (m_exiting)
-        return;
-
-    Q_ASSERT(ctx->thread() == QThread::currentThread());
-
-    // Make the context (and an offscreen surface) current for this thread. The
-    // QOpenGLWidget's fbo is bound in the context.
-    m_glwidget->makeCurrent();
-
-    if (!m_inited) {
-        m_inited = true;
-        initializeOpenGLFunctions();
-
-        QMutexLocker initLock(initMutex());
-        QOpenGLShader *vshader = new QOpenGLShader(QOpenGLShader::Vertex, this);
-        vshader->compileSourceCode(VERTEX_SHADER);
-
-        QOpenGLShader *fshader = new QOpenGLShader(QOpenGLShader::Fragment, this);
-        fshader->compileSourceCode(FRAGMENT_SHADER);
-
-        program.addShader(vshader);
-        program.addShader(fshader);
-        program.link();
-
-        vertexAttr = program.attributeLocation("vertex");
-        normalAttr = program.attributeLocation("normal");
-        matrixUniform = program.uniformLocation("matrix");
-
-        m_fAngle = 0;
-        m_fScale = 1;
-        createGeometry();
-
-        vbo.create();
-        vbo.bind();
-        const int verticesSize = vertices.count() * 3 * sizeof(GLfloat);
-        vbo.allocate(verticesSize * 2);
-        vbo.write(0, vertices.constData(), verticesSize);
-        vbo.write(verticesSize, normals.constData(), verticesSize);
-
-        m_elapsed.start();
-    }
-
-    //qDebug("%p elapsed %lld", QThread::currentThread(), m_elapsed.restart());
-
-    glClearColor(0.1f, 0.2f, 0.2f, 1.0f);
-    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
-
-    glFrontFace(GL_CW);
-    glCullFace(GL_FRONT);
-    glEnable(GL_CULL_FACE);
-    glEnable(GL_DEPTH_TEST);
-
-    QMatrix4x4 modelview;
-    modelview.rotate(m_fAngle, 0.0f, 1.0f, 0.0f);
-    modelview.rotate(m_fAngle, 1.0f, 0.0f, 0.0f);
-    modelview.rotate(m_fAngle, 0.0f, 0.0f, 1.0f);
-    modelview.scale(m_fScale);
-    modelview.translate(0.0f, -0.2f, 0.0f);
-
-    program.bind();
-    program.setUniformValue(matrixUniform, modelview);
-    paintQtLogo();
-    program.release();
-
-    glDisable(GL_DEPTH_TEST);
-    glDisable(GL_CULL_FACE);
-
-    m_fAngle += 1.0f;
-
-    // Make no context current on this thread and move the QOpenGLWidget's
-    // context back to the gui thread.
-    m_glwidget->doneCurrent();
-    ctx->moveToThread(qGuiApp->thread());
-
-    // Schedule composition. Note that this will use QueuedConnection, meaning
-    // that update() will be invoked on the gui thread.
-    QMetaObject::invokeMethod(m_glwidget, "update");
-}
-
-void Renderer::createGeometry()
-{
-    vertices.clear();
-    normals.clear();
-
-    qreal x1 = +0.06f;
-    qreal y1 = -0.14f;
-    qreal x2 = +0.14f;
-    qreal y2 = -0.06f;
-    qreal x3 = +0.08f;
-    qreal y3 = +0.00f;
-    qreal x4 = +0.30f;
-    qreal y4 = +0.22f;
-
-    quad(x1, y1, x2, y2, y2, x2, y1, x1);
-    quad(x3, y3, x4, y4, y4, x4, y3, x3);
-
-    extrude(x1, y1, x2, y2);
-    extrude(x2, y2, y2, x2);
-    extrude(y2, x2, y1, x1);
-    extrude(y1, x1, x1, y1);
-    extrude(x3, y3, x4, y4);
-    extrude(x4, y4, y4, x4);
-    extrude(y4, x4, y3, x3);
-
-    const int NumSectors = 100;
-    const qreal sectorAngle = 2 * qreal(M_PI) / NumSectors;
-
-    for (int i = 0; i < NumSectors; ++i) {
-        qreal angle = i * sectorAngle;
-        qreal sinAngle = sin(angle);
-        qreal cosAngle = cos(angle);
-        qreal x5 = 0.30 * sinAngle;
-        qreal y5 = 0.30 * cosAngle;
-        qreal x6 = 0.20 * sinAngle;
-        qreal y6 = 0.20 * cosAngle;
-
-        angle += sectorAngle;
-        sinAngle = sin(angle);
-        cosAngle = cos(angle);
-        qreal x7 = 0.20 * sinAngle;
-        qreal y7 = 0.20 * cosAngle;
-        qreal x8 = 0.30 * sinAngle;
-        qreal y8 = 0.30 * cosAngle;
-
-        quad(x5, y5, x6, y6, x7, y7, x8, y8);
-
-        extrude(x6, y6, x7, y7);
-        extrude(x8, y8, x5, y5);
-    }
-
-    for (qsizetype i = 0; i < vertices.size(); ++i)
-        vertices[i] *= 2.0f;
-}
-
-void Renderer::quad(qreal x1, qreal y1, qreal x2, qreal y2, qreal x3, qreal y3, qreal x4, qreal y4)
-{
-    vertices << QVector3D(x1, y1, -0.05f);
-    vertices << QVector3D(x2, y2, -0.05f);
-    vertices << QVector3D(x4, y4, -0.05f);
-
-    vertices << QVector3D(x3, y3, -0.05f);
-    vertices << QVector3D(x4, y4, -0.05f);
-    vertices << QVector3D(x2, y2, -0.05f);
-
-    QVector3D n = QVector3D::normal
-        (QVector3D(x2 - x1, y2 - y1, 0.0f), QVector3D(x4 - x1, y4 - y1, 0.0f));
-
-    normals << n;
-    normals << n;
-    normals << n;
-
-    normals << n;
-    normals << n;
-    normals << n;
-
-    vertices << QVector3D(x4, y4, 0.05f);
-    vertices << QVector3D(x2, y2, 0.05f);
-    vertices << QVector3D(x1, y1, 0.05f);
-
-    vertices << QVector3D(x2, y2, 0.05f);
-    vertices << QVector3D(x4, y4, 0.05f);
-    vertices << QVector3D(x3, y3, 0.05f);
-
-    n = QVector3D::normal
-        (QVector3D(x2 - x4, y2 - y4, 0.0f), QVector3D(x1 - x4, y1 - y4, 0.0f));
-
-    normals << n;
-    normals << n;
-    normals << n;
-
-    normals << n;
-    normals << n;
-    normals << n;
-}
-
-void Renderer::extrude(qreal x1, qreal y1, qreal x2, qreal y2)
-{
-    vertices << QVector3D(x1, y1, +0.05f);
-    vertices << QVector3D(x2, y2, +0.05f);
-    vertices << QVector3D(x1, y1, -0.05f);
-
-    vertices << QVector3D(x2, y2, -0.05f);
-    vertices << QVector3D(x1, y1, -0.05f);
-    vertices << QVector3D(x2, y2, +0.05f);
-
-    QVector3D n = QVector3D::normal
-        (QVector3D(x2 - x1, y2 - y1, 0.0f), QVector3D(0.0f, 0.0f, -0.1f));
-
-    normals << n;
-    normals << n;
-    normals << n;
-
-    normals << n;
-    normals << n;
-    normals << n;
-}

examples/opengl/threadedqopenglwidget/renderer.h

@@ -1,61 +0,0 @@
-// Copyright (C) 2022 The Qt Company Ltd.
-// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
-
-#ifndef RENDERER_H
-#define RENDERER_H
-
-#include <QOpenGLFunctions>
-#include <QOpenGLBuffer>
-#include <QOpenGLShaderProgram>
-#include <QVector3D>
-#include <QMatrix4x4>
-#include <QThread>
-#include <QMutex>
-#include <QWaitCondition>
-#include <QElapsedTimer>
-
-QT_FORWARD_DECLARE_CLASS(QOpenGLWidget)
-
-class Renderer : public QObject, protected QOpenGLFunctions
-{
-    Q_OBJECT
-
-public:
-    explicit Renderer(QOpenGLWidget *w);
-    void lockRenderer() { m_renderMutex.lock(); }
-    void unlockRenderer() { m_renderMutex.unlock(); }
-    QMutex *grabMutex() { return &m_grabMutex; }
-    QWaitCondition *grabCond() { return &m_grabCond; }
-    void prepareExit() { m_exiting = true; m_grabCond.wakeAll(); }
-
-signals:
-    void contextWanted();
-
-public slots:
-    void render();
-
-private:
-    void paintQtLogo();
-    void createGeometry();
-    void quad(qreal x1, qreal y1, qreal x2, qreal y2, qreal x3, qreal y3, qreal x4, qreal y4);
-    void extrude(qreal x1, qreal y1, qreal x2, qreal y2);
-
-    bool m_inited = false;
-    qreal m_fAngle = 0;
-    qreal m_fScale = 1;
-    QList<QVector3D> vertices;
-    QList<QVector3D> normals;
-    QOpenGLShaderProgram program;
-    QOpenGLBuffer vbo;
-    int vertexAttr = 0;
-    int normalAttr = 0;
-    int matrixUniform = 0;
-    QOpenGLWidget *m_glwidget = nullptr;
-    QMutex m_renderMutex;
-    QElapsedTimer m_elapsed;
-    QMutex m_grabMutex;
-    QWaitCondition m_grabCond;
-    bool m_exiting = false;
-};
-
-#endif // RENDERER_H

examples/opengl/threadedqopenglwidget/threadedqopenglwidget.pro

@@ -1,13 +0,0 @@
-QT += widgets opengl openglwidgets
-
-SOURCES += main.cpp \
-           glwidget.cpp \
-           mainwindow.cpp \
-           renderer.cpp
-
-HEADERS += glwidget.h \
-           mainwindow.h \
-           renderer.h
-
-target.path = $$[QT_INSTALL_EXAMPLES]/opengl/threadedqopenglwidget
-INSTALLS += target