How do I enable multisampling (antialiasing) in OpenGL with Qt5?

Question

How do I enable multisampling when I create the window? How should I initialize OpenGL to match?

Desdamona

Answer 1

Took me a while to figure this one out.

The trick is to use a QSurfaceFormat in your QWindow's constructor like so:

setSurfaceType(QWindow::OpenGLSurface);
QSurfaceFormat format;
format.setSamples(4);    // Set the number of samples used for multisampling
setFormat(format);       // Note we set the format on the window...
create();                // Create the window

context = new QOpenGLContext(this);
context->setFormat(format);    // ...and set the format on the context too
context->create();

And later, when initialising OpenGL:

glEnable(GL_MULTISAMPLE);    // This seems to be the default given the configuration above, but just in case that's not universal...

Desdamona

really strange, what is the point in setting it on the QOpenGLContext if QWindow will just do its own thing – Bathulda

@paulm: No idea, I just fiddled with stuff until it worked ;-) – Desdamona