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#include <QGuiApplication>
#include <QSurfaceFormat>
#include <QOffscreenSurface>
#include <QOpenGLContext>
#include <QDebug>
#include <QPair>
#include "glwindow.h"

bool OGLSupports(int major, int minor, bool gles = false)
{
    QOpenGLContext ctx;
    QSurfaceFormat fmt;
    fmt.setVersion(major, minor);
    if (gles)
        fmt.setRenderableType(QSurfaceFormat::OpenGLES);
    else
        fmt.setRenderableType(QSurfaceFormat::OpenGL);

    ctx.setFormat(fmt);
    ctx.create();
    if (!ctx.isValid())
        return false;
    int ctxMajor = ctx.format().majorVersion();
    int ctxMinor = ctx.format().minorVersion();
    bool isGles = (ctx.format().renderableType() == QSurfaceFormat::OpenGLES);

    if (isGles != gles) return false;
    if (ctxMajor < major) return false;
    if (ctxMajor == major && ctxMinor < minor)
        return false;
    return true;
}

int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);

    qDebug() << "Support for GL 2.0   "<<( OGLSupports(2,0) ? "yes" : "no");
    qDebug() << "Support for GL 2.1   "<<( OGLSupports(2,1) ? "yes" : "no");
    qDebug() << "Support for GL 3.0   "<<( OGLSupports(3,0) ? "yes" : "no");
    qDebug() << "Support for GL 3.1   "<<( OGLSupports(3,1) ? "yes" : "no");
    qDebug() << "Support for GL 3.2   "<<( OGLSupports(3,2) ? "yes" : "no");
    qDebug() << "Support for GL 3.3   "<<( OGLSupports(3,3) ? "yes" : "no");
    qDebug() << "Support for GL 4.0   "<<( OGLSupports(4,0) ? "yes" : "no");
    qDebug() << "Support for GL 4.1   "<<( OGLSupports(4,1) ? "yes" : "no");
    qDebug() << "Support for GL 4.2   "<<( OGLSupports(4,2) ? "yes" : "no");
    qDebug() << "Support for GL 4.3   "<<( OGLSupports(4,3) ? "yes" : "no");
    qDebug() << "Support for GL 4.4   "<<( OGLSupports(4,4) ? "yes" : "no");
    qDebug() << "Support for GL 4.5   "<<( OGLSupports(4,5) ? "yes" : "no");
    qDebug() << "Support for GLES 2.0 "<<( OGLSupports(2,0,true) ? "yes" : "no");
    qDebug() << "Support for GLES 3.0 "<<( OGLSupports(3,0,true) ? "yes" : "no");
    qDebug() << "Support for GLES 3.1 "<<( OGLSupports(3,1,true) ? "yes" : "no");
    qDebug() << "Support for GLES 3.2 "<<( OGLSupports(3,2,true) ? "yes" : "no");

    QSurfaceFormat fmt;
    fmt.setDepthBufferSize(24);

    // Request OpenGL 4.3 compatibility or OpenGL ES 3.1.
    if (OGLSupports(4,3)) {
        qDebug("Requesting 4.3 compatibility context");
        fmt.setVersion(4, 3);
        fmt.setRenderableType(QSurfaceFormat::OpenGL);
        fmt.setProfile(QSurfaceFormat::CompatibilityProfile);
    } else if (OGLSupports(3,1,true)) {
        qDebug("Requesting 3.1 GLES context");
        fmt.setVersion(3, 1);
        fmt.setRenderableType(QSurfaceFormat::OpenGLES);
    } else {
        qWarning("Error: This system does not support OpenGL Compute Shaders! Exiting.");
        return -1;
    }
    QSurfaceFormat::setDefaultFormat(fmt);

    GLWindow glWindow;
    glWindow.showMaximized();

    return app.exec();
}