Qt and OpenGL

Question

Qt

Hello. There is a game on sfml (opengl). Everything is cool, it suits. It's time for a complex GUI (editor and game). Before that, I used the libRocket library, but somehow it’s crooked: there are no sane docks, the forum is silent, it’s terribly difficult to set up controls (with my 4-year experience in layout).
So I decided to take something more flexible. I came across QT. Used for a long time, but for desktop applications.
Question: how slow will it be to redirect output to some qt widget and use its controls on top? As I saw, the latest versions (including qt 5) are already fully able to draw on the video card. The most important thing for me is speed. If it doesn’t work at normal speed, then I won’t use it.

What do you say?

Answer 1

A lot of editors for graphics engines use Qt for the GUI. The render speed does not change compared to output to one (or changes almost imperceptibly).

Answer 2

What can I tell you? So so. You have two options so far. You can write on widgets or on kuml. Qt Widgets will probably be deprecated soon - so I advise QML. He, as the colleague said above, is rendered on OpenGL. How many brakes did not work with him — did not notice.
As for the widgets - they are good. A month ago I used them with might and main. Now I only support old projects on them.

Answer 3

Widgets can be rendered to a texture. Regarding the speed, download the SDK, there are the necessary examples, including OpenGL, you can evaluate the performance.

Answer 4

QtQuick 2.0 (aka QML from Qt5) renders via OpenGL