Add support for stereoscopic content in QOpenGLWidget

Need to add the plumbing necessary to support two textures in QOpenGLWidget and use these in the backing store. The changes required on the RHI level is already done in an earlier patch. Then paintGL() needs to be called twice, once for each buffer. Also add overloads for the other functions of QOopenGLWidget where it makes sense to query for left or right buffer. Then finally create an example. [ChangeLog][Widgets][QOpenGLWidget] Added support for stereoscopic rendering. Fixes: QTBUG-64587 Change-Id: I5a5c53506dcf8a56442097290dceb7eb730d50ce Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>
author: Kristoffer Skau <kristoffer.skau@qt.io> 2022-10-27 15:38:53 +0200
committer: Kristoffer Skau <kristoffer.skau@qt.io> 2022-11-28 19:12:27 +0100
commit: ee2dbcada81f5220a05414d7bf9d5eeebdda8972 (patch)
tree: 2bca1fc0c3569a98f26a0717d9e555a9b88f2364 /examples/opengl/stereoqopenglwidget
parent: 8155bd54261688f333b2d68e2d76f0fc076a0fb4 (diff)
7 files changed, 459 insertions, 0 deletions
diff --git a/examples/opengl/stereoqopenglwidget/CMakeLists.txt b/examples/opengl/stereoqopenglwidget/CMakeLists.txt
new file mode 100644
index 00000000000..69fd304bb22
--- /dev/null
+++ b/examples/opengl/stereoqopenglwidget/CMakeLists.txt
@@ -0,0 +1,41 @@
+# Copyright (C) 2022 The Qt Company Ltd.
+# SPDX-License-Identifier: BSD-3-Clause
+
+cmake_minimum_required(VERSION 3.16)
+project(stereoqopenglwidget LANGUAGES CXX)
+
+set(CMAKE_AUTOMOC ON)
+
+if(NOT DEFINED INSTALL_EXAMPLESDIR)
+    set(INSTALL_EXAMPLESDIR "examples")
+endif()
+
+set(INSTALL_EXAMPLEDIR "${INSTALL_EXAMPLESDIR}/opengl/stereoqopenglwidget")
+
+find_package(Qt6 REQUIRED COMPONENTS Core Gui OpenGL OpenGLWidgets Widgets)
+
+qt_add_executable(stereoqopenglwidget
+    glwidget.cpp glwidget.h
+    main.cpp
+    mainwindow.cpp mainwindow.h
+)
+
+set_target_properties(stereoqopenglwidget PROPERTIES
+    WIN32_EXECUTABLE TRUE
+    MACOSX_BUNDLE TRUE
+)
+
+target_link_libraries(stereoqopenglwidget PUBLIC
+    Qt::Core
+    Qt::Gui
+    Qt::OpenGL
+    Qt::OpenGLWidgets
+    Qt::Widgets
+)
+
+
+install(TARGETS stereoqopenglwidget
+    RUNTIME DESTINATION "${INSTALL_EXAMPLEDIR}"
+    BUNDLE DESTINATION "${INSTALL_EXAMPLEDIR}"
+    LIBRARY DESTINATION "${INSTALL_EXAMPLEDIR}"
+)
diff --git a/examples/opengl/stereoqopenglwidget/glwidget.cpp b/examples/opengl/stereoqopenglwidget/glwidget.cpp
new file mode 100644
index 00000000000..36a6300348e
--- /dev/null
+++ b/examples/opengl/stereoqopenglwidget/glwidget.cpp
@@ -0,0 +1,277 @@
+// Copyright (C) 2022 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#include "glwidget.h"
+#include <QPainter>
+#include <QPaintEngine>
+#include <QOpenGLShaderProgram>
+#include <QOpenGLTexture>
+#include <QRandomGenerator>
+#include <QCoreApplication>
+#include <QFileDialog>
+#include <qmath.h>
+
+GLWidget::GLWidget(const QColor &background)
+    : m_background(background)
+{
+    setMinimumSize(300, 250);
+}
+
+GLWidget::~GLWidget()
+{
+    reset();
+}
+
+void GLWidget::saveImage(TargetBuffer targetBuffer)
+{
+    QImage img = grabFramebuffer(targetBuffer);
+    if (img.isNull()) {
+        qFatal("Failed to grab framebuffer");
+    }
+
+    const char *fn =
+            targetBuffer == TargetBuffer::LeftBuffer
+            ? "leftBuffer.png" : "rightBuffer.png";
+
+    QFileDialog fd(this);
+    fd.setAcceptMode(QFileDialog::AcceptSave);
+    fd.setDefaultSuffix("png");
+    fd.selectFile(fn);
+    if (fd.exec() == QDialog::Accepted)
+        img.save(fd.selectedFiles().first());
+}
+
+void GLWidget::reset()
+{
+    // And now release all OpenGL resources.
+    makeCurrent();
+    delete m_program;
+    m_program = nullptr;
+    delete m_vshader;
+    m_vshader = nullptr;
+    delete m_fshader;
+    m_fshader = nullptr;
+    m_vbo.destroy();
+    doneCurrent();
+
+    // We are done with the current QOpenGLContext, forget it. If there is a
+    // subsequent initialize(), that will then connect to the new context.
+    QObject::disconnect(m_contextWatchConnection);
+}
+void GLWidget::initializeGL()
+{
+    initializeOpenGLFunctions();
+
+    m_vshader = new QOpenGLShader(QOpenGLShader::Vertex);
+    const char *vsrc1 =
+        "attribute highp vec4 vertex;\n"
+        "attribute mediump vec3 normal;\n"
+        "uniform mediump mat4 matrix;\n"
+        "varying mediump vec4 color;\n"
+        "void main(void)\n"
+        "{\n"
+        "    vec3 toLight = normalize(vec3(0.0, 0.3, 1.0));\n"
+        "    float angle = max(dot(normal, toLight), 0.0);\n"
+        "    vec3 col = vec3(0.40, 1.0, 0.0);\n"
+        "    color = vec4(col * 0.2 + col * 0.8 * angle, 1.0);\n"
+        "    color = clamp(color, 0.0, 1.0);\n"
+        "    gl_Position = matrix * vertex;\n"
+        "}\n";
+    m_vshader->compileSourceCode(vsrc1);
+
+    m_fshader = new QOpenGLShader(QOpenGLShader::Fragment);
+    const char *fsrc1 =
+        "varying mediump vec4 color;\n"
+        "void main(void)\n"
+        "{\n"
+        "    gl_FragColor = color;\n"
+        "}\n";
+    m_fshader->compileSourceCode(fsrc1);
+
+    m_program = new QOpenGLShaderProgram;
+    m_program->addShader(m_vshader);
+    m_program->addShader(m_fshader);
+    m_program->link();
+
+
+    m_vertexAttr = m_program->attributeLocation("vertex");
+    m_normalAttr = m_program->attributeLocation("normal");
+    m_matrixUniform = m_program->uniformLocation("matrix");
+
+    createGeometry();
+
+    m_vbo.create();
+    m_vbo.bind();
+    const int vertexCount = m_vertices.count();
+    QList<GLfloat> buf;
+    buf.resize(vertexCount * 3 * 2);
+    GLfloat *p = buf.data();
+    for (int i = 0; i < vertexCount; ++i) {
+        *p++ = m_vertices[i].x();
+        *p++ = m_vertices[i].y();
+        *p++ = m_vertices[i].z();
+        *p++ = m_normals[i].x();
+        *p++ = m_normals[i].y();
+        *p++ = m_normals[i].z();
+    }
+    m_vbo.allocate(buf.constData(), (int)buf.count() * sizeof(GLfloat));
+    m_vbo.release();
+
+    m_contextWatchConnection = QObject::connect(context(), &QOpenGLContext::aboutToBeDestroyed, context(), [this] { reset(); });
+
+    glFrontFace(GL_CW);
+    glCullFace(GL_FRONT);
+    glEnable(GL_CULL_FACE);
+    glEnable(GL_DEPTH_TEST);
+}
+
+void GLWidget::paintGL()
+{
+    // When QSurfaceFormat::StereoBuffers is enabled, this function is called twice.
+    // Once where currentTargetBuffer() == QOpenGLWidget::LeftBuffer,
+    // and once where currentTargetBuffer() == QOpenGLWidget::RightBuffer.
+
+    glClearColor(m_background.redF(), m_background.greenF(), m_background.blueF(), 1.0f);
+
+    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+    //! [1]
+    // Slightly translate the model, so that there's a visible difference in each buffer.
+    QMatrix4x4 modelview;
+    if (currentTargetBuffer() == QOpenGLWidget::LeftBuffer)
+        modelview.translate(-0.4f, 0.0f, 0.0f);
+    else if (currentTargetBuffer() == QOpenGLWidget::RightBuffer)
+        modelview.translate(0.4f, 0.0f, 0.0f);
+     //! [1]
+
+    m_program->bind();
+    m_program->setUniformValue(m_matrixUniform, modelview);
+    m_program->enableAttributeArray(m_vertexAttr);
+    m_program->enableAttributeArray(m_normalAttr);
+
+    m_vbo.bind();
+    m_program->setAttributeBuffer(m_vertexAttr, GL_FLOAT, 0, 3, 6 * sizeof(GLfloat));
+    m_program->setAttributeBuffer(m_normalAttr, GL_FLOAT, 3 * sizeof(GLfloat), 3, 6 * sizeof(GLfloat));
+    m_vbo.release();
+
+    glDrawArrays(GL_TRIANGLES, 0, m_vertices.size());
+
+    m_program->disableAttributeArray(m_normalAttr);
+    m_program->disableAttributeArray(m_vertexAttr);
+    m_program->release();
+    update();
+}
+
+void GLWidget::createGeometry()
+{
+    m_vertices.clear();
+    m_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 x5 = 0.30 * sin(angle);
+        qreal y5 = 0.30 * cos(angle);
+        qreal x6 = 0.20 * sin(angle);
+        qreal y6 = 0.20 * cos(angle);
+
+        angle += sectorAngle;
+        qreal x7 = 0.20 * sin(angle);
+        qreal y7 = 0.20 * cos(angle);
+        qreal x8 = 0.30 * sin(angle);
+        qreal y8 = 0.30 * cos(angle);
+
+        quad(x5, y5, x6, y6, x7, y7, x8, y8);
+
+        extrude(x6, y6, x7, y7);
+        extrude(x8, y8, x5, y5);
+    }
+
+    for (int i = 0;i < m_vertices.size();i++)
+        m_vertices[i] *= 2.0f;
+}
+
+void GLWidget::quad(qreal x1, qreal y1, qreal x2, qreal y2, qreal x3, qreal y3, qreal x4, qreal y4)
+{
+    m_vertices << QVector3D(x1, y1, -0.05f);
+    m_vertices << QVector3D(x2, y2, -0.05f);
+    m_vertices << QVector3D(x4, y4, -0.05f);
+
+    m_vertices << QVector3D(x3, y3, -0.05f);
+    m_vertices << QVector3D(x4, y4, -0.05f);
+    m_vertices << QVector3D(x2, y2, -0.05f);
+
+    QVector3D n = QVector3D::normal
+        (QVector3D(x2 - x1, y2 - y1, 0.0f), QVector3D(x4 - x1, y4 - y1, 0.0f));
+
+    m_normals << n;
+    m_normals << n;
+    m_normals << n;
+
+    m_normals << n;
+    m_normals << n;
+    m_normals << n;
+
+    m_vertices << QVector3D(x4, y4, 0.05f);
+    m_vertices << QVector3D(x2, y2, 0.05f);
+    m_vertices << QVector3D(x1, y1, 0.05f);
+
+    m_vertices << QVector3D(x2, y2, 0.05f);
+    m_vertices << QVector3D(x4, y4, 0.05f);
+    m_vertices << QVector3D(x3, y3, 0.05f);
+
+    n = QVector3D::normal
+        (QVector3D(x2 - x4, y2 - y4, 0.0f), QVector3D(x1 - x4, y1 - y4, 0.0f));
+
+    m_normals << n;
+    m_normals << n;
+    m_normals << n;
+
+    m_normals << n;
+    m_normals << n;
+    m_normals << n;
+}
+
+void GLWidget::extrude(qreal x1, qreal y1, qreal x2, qreal y2)
+{
+    m_vertices << QVector3D(x1, y1, +0.05f);
+    m_vertices << QVector3D(x2, y2, +0.05f);
+    m_vertices << QVector3D(x1, y1, -0.05f);
+
+    m_vertices << QVector3D(x2, y2, -0.05f);
+    m_vertices << QVector3D(x1, y1, -0.05f);
+    m_vertices << QVector3D(x2, y2, +0.05f);
+
+    QVector3D n = QVector3D::normal
+        (QVector3D(x2 - x1, y2 - y1, 0.0f), QVector3D(0.0f, 0.0f, -0.1f));
+
+    m_normals << n;
+    m_normals << n;
+    m_normals << n;
+
+    m_normals << n;
+    m_normals << n;
+    m_normals << n;
+}
diff --git a/examples/opengl/stereoqopenglwidget/glwidget.h b/examples/opengl/stereoqopenglwidget/glwidget.h
new file mode 100644
index 00000000000..0014ee37c1b
--- /dev/null
+++ b/examples/opengl/stereoqopenglwidget/glwidget.h
@@ -0,0 +1,53 @@
+// 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>
+#include <QOpenGLFunctions>
+#include <QOpenGLBuffer>
+#include <QVector3D>
+#include <QMatrix4x4>
+#include <QElapsedTimer>
+#include <QList>
+#include <QPushButton>
+
+
+QT_FORWARD_DECLARE_CLASS(QOpenGLTexture)
+QT_FORWARD_DECLARE_CLASS(QOpenGLShader)
+QT_FORWARD_DECLARE_CLASS(QOpenGLShaderProgram)
+
+class GLWidget : public QOpenGLWidget, protected QOpenGLFunctions
+{
+    Q_OBJECT
+public:
+    GLWidget(const QColor &background);
+    ~GLWidget();
+
+    void saveImage(QOpenGLWidget::TargetBuffer targetBuffer);
+
+protected:
+    void paintGL() override;
+    void initializeGL() override;
+
+private:
+    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);
+    void reset();
+
+    QList<QVector3D> m_vertices;
+    QList<QVector3D> m_normals;
+    QOpenGLShader *m_vshader = nullptr;
+    QOpenGLShader *m_fshader = nullptr;
+    QOpenGLShaderProgram *m_program = nullptr;
+    QOpenGLBuffer m_vbo;
+    int m_vertexAttr;
+    int m_normalAttr;
+    int m_matrixUniform;
+    QColor m_background;
+    QMetaObject::Connection m_contextWatchConnection;
+};
+
+#endif
diff --git a/examples/opengl/stereoqopenglwidget/main.cpp b/examples/opengl/stereoqopenglwidget/main.cpp
new file mode 100644
index 00000000000..8aad756ecab
--- /dev/null
+++ b/examples/opengl/stereoqopenglwidget/main.cpp
@@ -0,0 +1,31 @@
+// Copyright (C) 2022 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#include <QApplication>
+#include <QSurfaceFormat>
+#include "mainwindow.h"
+
+int main( int argc, char ** argv )
+{
+    QApplication a( argc, argv );
+
+    QCoreApplication::setApplicationName("Qt QOpenGLWidget Stereoscopic Rendering Example");
+    QCoreApplication::setOrganizationName("QtProject");
+    QCoreApplication::setApplicationVersion(QT_VERSION_STR);
+
+    //! [1]
+    QSurfaceFormat format;
+    format.setDepthBufferSize(24);
+    format.setStencilBufferSize(8);
+
+    // Enable stereoscopic rendering support
+    format.setStereo(true);
+
+    QSurfaceFormat::setDefaultFormat(format);
+    //! [1]
+
+    MainWindow mw;
+    mw.resize(1280, 720);
+    mw.show();
+    return a.exec();
+}
diff --git a/examples/opengl/stereoqopenglwidget/mainwindow.cpp b/examples/opengl/stereoqopenglwidget/mainwindow.cpp
new file mode 100644
index 00000000000..33f93ba7de8
--- /dev/null
+++ b/examples/opengl/stereoqopenglwidget/mainwindow.cpp
@@ -0,0 +1,25 @@
+// Copyright (C) 2022 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#include "mainwindow.h"
+#include <QApplication>
+#include <QMenuBar>
+#include "glwidget.h"
+
+MainWindow::MainWindow()
+{
+    GLWidget *glwidget = new GLWidget(qRgb(20, 20, 50));
+    setCentralWidget(glwidget);
+
+    QMenu *screenShotMenu = menuBar()->addMenu("&Screenshot");
+    screenShotMenu->addAction("Left buffer", this, [glwidget](){
+        glwidget->saveImage(QOpenGLWidget::LeftBuffer);
+    });
+
+    screenShotMenu->addAction("Right buffer", this, [glwidget](){
+        glwidget->saveImage(QOpenGLWidget::RightBuffer);
+    });
+
+    QMenu *helpMenu = menuBar()->addMenu("&Help");
+    helpMenu->addAction("About Qt", qApp, &QApplication::aboutQt);
+}
diff --git a/examples/opengl/stereoqopenglwidget/mainwindow.h b/examples/opengl/stereoqopenglwidget/mainwindow.h
new file mode 100644
index 00000000000..aa6f722e590
--- /dev/null
+++ b/examples/opengl/stereoqopenglwidget/mainwindow.h
@@ -0,0 +1,21 @@
+// Copyright (C) 2022 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#ifndef MAINWINDOW_H
+#define MAINWINDOW_H
+
+#include <QMainWindow>
+#include <QTimer>
+#include <QGridLayout>
+
+QT_FORWARD_DECLARE_CLASS(QOpenGLWidget)
+
+class MainWindow : public QMainWindow
+{
+    Q_OBJECT
+
+public:
+    MainWindow();
+};
+
+#endif
diff --git a/examples/opengl/stereoqopenglwidget/stereoqopenglwidget.pro b/examples/opengl/stereoqopenglwidget/stereoqopenglwidget.pro
new file mode 100644
index 00000000000..197afff571e
--- /dev/null
+++ b/examples/opengl/stereoqopenglwidget/stereoqopenglwidget.pro
@@ -0,0 +1,11 @@
+QT += widgets opengl openglwidgets
+
+SOURCES += main.cpp \
+           glwidget.cpp \
+           mainwindow.cpp
+
+HEADERS += glwidget.h \
+           mainwindow.h
+
+target.path = $$[QT_INSTALL_EXAMPLES]/opengl/stereoqopenglwidget
+INSTALLS += target
author	Kristoffer Skau <kristoffer.skau@qt.io>	2022-10-27 15:38:53 +0200
committer	Kristoffer Skau <kristoffer.skau@qt.io>	2022-11-28 19:12:27 +0100
commit	ee2dbcada81f5220a05414d7bf9d5eeebdda8972 (patch)
tree	2bca1fc0c3569a98f26a0717d9e555a9b88f2364 /examples/opengl/stereoqopenglwidget
parent	8155bd54261688f333b2d68e2d76f0fc076a0fb4 (diff)