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?

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...