[Interest] OpenGL: Setting samples on default QSurfaceFormat

[Giuseppe D'Angelo]

Il 19/09/2018 15:02, Andy ha scritto:
> 
> Any thoughts on the second part about why I get a 3.0 context if I try 
> to set samples instead of the 3.3 I get when I don't? On macOS if I 
> request 16 samples, and it can only do 8, I get 8.

That now boils down to how the different integration layers (GLX, CGL, 
WGL, EGL) implement these fallbacks, both internally as well as in Qt 
itself.

(Yes, it's a huge, unpleasant mess where both the underlying levels try 
to be "too smart", and implement various fallback strategies. Thus 
Sean's suggestion of try, check if you like what you get back, if not 
try again with different parameters.)

So, it could just be that Qt+CGL accept the context version and other 
parameters but simply reduce the number of samples, while Qt+GLX (+ 
Mesa) do something entirely different. In either case you need to create 
a context/window and check that what you've got is OK for you.

HTH,

-- 
Giuseppe D'Angelo | giuseppe.dangelo at kdab.com | Senior Software Engineer
KDAB (France) S.A.S., a KDAB Group company
Tel. France +33 (0)4 90 84 08 53, http://www.kdab.com
KDAB - The Qt, C++ and OpenGL Experts

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