OpenGLDetection.hh

 
namespace
{
    
// Print human-readable GL profile strings
std::string profileToString(QSurfaceFormat::OpenGLContextProfile _profile)
{
    if(_profile == QSurfaceFormat::CompatibilityProfile)
        return "CompatibilityProfile";
 
    if(_profile == QSurfaceFormat::CoreProfile)
        return "CoreProfile";
 
    if(_profile == QSurfaceFormat::NoProfile)
        return "NoProfile";
 
    return "[Unknown]";
}
 
// Check whether a specific context request can be fulfilled
// Can also return the format of the actually created context
bool verifySpecificContextFormat(QSurfaceFormat format, QSurfaceFormat* resultingFormat = nullptr)
{
    // All created surfaces try to obey the given format
    QSurfaceFormat::setDefaultFormat(format);
 
    // We need a temporary qApp to create a surface and test the current context
    int tempArgC = 0;
    QApplication tempApp(tempArgC, nullptr);
    QOffscreenSurface *surface = new QOffscreenSurface();
    surface->create();
 
    auto shareContext = QOpenGLContext::globalShareContext();
    if(!shareContext)
    {
        std::cerr << "Error: Apparently no GL context was created!" << std::endl;
        return false;
    }
 
    // Make the globally shared OpenGLContext current
    shareContext->makeCurrent(surface);
 
    // The opengl surface properties that have actually been applied
    // (does not necessarily match the requested properties)
    auto resultFormat = QOpenGLContext::globalShareContext()->format();
 
    // Return the format of the actually created context (may be identical to the requested one)
    if(resultingFormat != nullptr)
        *resultingFormat = resultFormat;
 
    auto curVersion = resultFormat.version();
 
    // Human-readable name of requested profile
    auto reqProfileString = profileToString(format.profile());
 
    // Human-readable name of current profile
    auto curProfileString = profileToString(resultFormat.profile());
 
    
    // Example: OpenGL Version 4.6 -> 46
    auto reqVersionInt = format.version().first * 10 + format.version().second;
    auto curVersionInt = curVersion.first * 10 + curVersion.second;
    
    
 
    // We set the following guidelines:
    // 1. Whenever the actually received GL version is < than the requested one, the context is not the one requested
    // 2. If the received profile is not the requested one, the context is not the one requested
        
    if(curVersionInt < 32 && resultFormat.profile() == QSurfaceFormat::CoreProfile)
    {
        std::cerr << "Warning: Got an OpenGL core context with OpengGL version < 3.2 (" << curVersion.first << "." << curVersion.second << ")! This should not be possible." << std::endl;
        return false;
    }
    
    // Check whether the conditions above are met.
    // If not, print some error to the console
    if(curVersionInt < reqVersionInt ||
       format.profile()!= resultFormat.profile() )
    {
        std::cout << "[OpenGL context] Requested: "
                  << format.version().first << "." << format.version().second << " (" << reqProfileString << ")"
                  << ", Actually created: "
                  << curVersion.first << "." << curVersion.second << " (" << curProfileString << ")"
                  << std::endl;
        return false;
    }
 
    std::cout << "[OpenGL context] Successfully created OpenGL context with version " << curVersion.first << "."
              << curVersion.second << " (" << curProfileString << ")." << std::endl;
 
    if ( format.testOption(QSurfaceFormat::DebugContext) )
        std::cout << "[OpenGL context] Created Debug Context" << std::endl;
 
    return true;
}
 
// Create a QSurfaceFormat from the most important properties like version and profile
QSurfaceFormat createFormat(QSurfaceFormat::OpenGLContextProfile _profile, int _glMajor, int _glMinor, int _multisamplingSamples, bool _stereo, bool _debugContext)
{
    QSurfaceFormat format;
    format.setVersion(_glMajor, _glMinor);
    format.setProfile(_profile);
    format.setSamples(_multisamplingSamples);
    format.setStereo(_stereo);
    if(_profile != QSurfaceFormat::CoreProfile)
        format.setOption(QSurfaceFormat::DeprecatedFunctions);
    if (_debugContext)
        format.setOption(QSurfaceFormat::DebugContext);
 
    return format;
}
 
// This method tries to find the best possible OpenGL context format in the following order:
// 1. The profile/format requested via the settings
// 2. A 4.4 compatibility context (should contain all relevant GL functions)
// 3. A 3.2 core context (best choice e.g. on MacOS)
// 4. Return whatever context was applied instead of the requested ones
QSurfaceFormat getContextFormat()
{
    auto reqProfile = OpenFlipper::Options::coreProfile() ? QSurfaceFormat::CoreProfile : QSurfaceFormat::CompatibilityProfile;
    QPair<int,int> reqVersion = OpenFlipper::Options::glVersion();
    auto reqSamples = OpenFlipper::Options::samples();
    auto reqStereo = OpenFlipper::Options::glStereo();
    bool debugContext = OpenFlipper::Options::debug();
 
 
 
    /*
    // Debug: test all (possible and impossible) OpenGL versions and profiles and exit
    for(int majo = 1; majo < 5; ++majo)
        for(int mino = 0; mino < 10; ++mino)
    {
        std::cout << "========== " << majo << "." << mino << " ==========="<<std::endl;
        verifySpecificContextFormat(createFormat(QSurfaceFormat::CoreProfile, majo, mino, reqSamples, reqStereo, debugContext));
        verifySpecificContextFormat(createFormat(QSurfaceFormat::CompatibilityProfile, majo, mino, reqSamples, reqStereo, debugContext));
        verifySpecificContextFormat(createFormat(QSurfaceFormat::NoProfile, majo, mino, reqSamples, reqStereo, debugContext));
        std::cout << "================================" << std::endl;
        std::cout << std::endl;
    }
    exit(0);
    */
 
 
 
    QSurfaceFormat resultFormat;
 
 
    std::cout << "[OpenGL context] Trying to create a " << reqVersion.first << "." << reqVersion.second << " " << profileToString(reqProfile) << " context (default from settings)..." << std::endl;
    bool success = verifySpecificContextFormat(createFormat(reqProfile, reqVersion.first, reqVersion.second, reqSamples, reqStereo, debugContext), &resultFormat);
 
    // If that did not work...
    if(!success)
    {
        std::cout << "[OpenGL context] Trying to create a 4.4 compat context..." << std::endl;
        success = verifySpecificContextFormat(createFormat(QSurfaceFormat::CompatibilityProfile, 4, 4, reqSamples, reqStereo, debugContext), &resultFormat);
        
        if(!success)
        {
            std::cout << "[OpenGL context] Trying to create a 3.2 core context..." << std::endl;
            success = verifySpecificContextFormat(createFormat(QSurfaceFormat::CoreProfile, 3, 2, reqSamples, reqStereo, debugContext), &resultFormat);
            if(!success)
            {
                std::cerr << "[OpenGL context] Warning: Could not create any of the requested GL contexts." << std::endl;
                std::cerr << "[OpenGL context] The following context (proposed by the graphics driver) will be created:"  << std::endl;
                std::cerr << "[OpenGL context] Profile: " << profileToString(resultFormat.profile()) << ", Version: "
                          << resultFormat.version().first << "." << resultFormat.version().second << std::endl;
                std::cerr << "[OpenGL context] Please consider setting a supported OpenGL version and profile in the Options dialog." << std::endl;
            }
        }
    }
 
    return resultFormat;
}
 
}