Console application with OpenGL

[Zingam]

I want to create a console application that just uses Compute Shaders. I don't need any GUI. So I thought that Qt can help me get a context. Then I want to use GLEW or GL3W for loading the OpenGL functions.

Can I have something like that:

#include "GL/gl3w.h"

#include <QtCore/QDebug>
#include <QtGui/QSurfaceFormat>
#include <QtGui/QOpenGlContext>


using namespace std;

int main()
{
   QSurfaceFormat surfaceFormat;
   surfaceFormat.setMajorVersion(4);
   surfaceFormat.setMinorVersion(3);
   QOpenGLContext openGLContext;
   openGLContext.setFormat(surfaceFormat);
   openGLContext.create();

if (openGLContext.isValid())
{
    qDebug() << "OpenGL version: ";
}
else
{
    qDebug() << "Could not create an OpenGL context";
}


if (gl3wInit()) {
                fprintf(stderr, "failed to initialize OpenGL\n");
                return -1;
        }
        if (!gl3wIsSupported(3, 2)) {
                fprintf(stderr, "OpenGL 3.2 not supported\n");
                return -1;
        }
        printf("OpenGL %s, GLSL %s\n", glGetString(GL_VERSION),
               glGetString(GL_SHADING_LANGUAGE_VERSION));

return 0;

}

[Chris Kawa]

No, that's not enough.
Creating OpenGL context requires a QGuiApplication instance (even in a console app) and a surface to make the context current on.

Also, if you're already using Qt anyway why bringing in another library for OpenGL handling? Qt already has everything you need to create a core profile context and it's one less dependency.

Here'a s minimal example:

#include <QGuiApplication>
#include <QSurfaceFormat>
#include <QOpenGlContext>
#include <QOffscreenSurface>
#include <QOpenGLFunctions_4_3_Core>
#include <QDebug>

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

   QSurfaceFormat surfaceFormat;
   surfaceFormat.setMajorVersion(4);
   surfaceFormat.setMinorVersion(3);

   QOpenGLContext openGLContext;
   openGLContext.setFormat(surfaceFormat);
   openGLContext.create();
   if(!openGLContext.isValid()) return -1;

   QOffscreenSurface surface;
   surface.setFormat(surfaceFormat);
   surface.create();
   if(!surface.isValid()) return -2;

   openGLContext.makeCurrent(&surface);

   QOpenGLFunctions_4_3_Core f;
   if(!f.initializeOpenGLFunctions()) return -3;

   qDebug() << QString::fromLatin1((const char*)f.glGetString(GL_VERSION));

   return 0;
}