Difference in opengl speed between Qt 4/5 and Opengl API

Question

I have read all the questions on SO that i could find about qt 4 and 5 opengl. This one came the closest OpenGL vs QOpenGL/QtOpenGL in Qt 5: differences and limitations? ,

Answer 1

I think that there is a lot of misunderstanding in your question and in the comments it received. The root of the problem is the very loose use of the term "Qt".

Qt is a big cross-platform application development framework. It combines features offered by many stand-alone frameworks. It offers a lot of functionality that is entirely non-gui-related. Namely cross-platform containers, threads, variants, meta object system with introspection, timers, networking, scripting using either qtscript or javascript (via qml), xml, json, state machines, and others. Qt is used for writing web services, for example, without a single line of UI code anywhere.

When it comes to user interface, Qt offers you four UI toolkits. It is entirely your choice which toolkit one you end up using. You can also mix-and-match all of them - you can have parts of your UI implemented in one toolkit, parts in another. Everything depends on your requirements.

I presume that by "Qt5" you mean Qt Quick 2, an implementation of a scene graph and UI toolkit using QML as the description/scripting platform. If all you need is a 2D, scenegraph-based toolkit, then Qt Quick 2 is a good choice. It does not offer any 3D functionality, so for 3D features you're on your own. Qt won't get in your way - in fact, it will help you, since it provides a portable wrapper API for OpenGL that hides some platform differences in getting access to OpenGL. It also provides ANGLE, a bundled implementation of OpenGL on top of Direct3D. This lets you develop in OpenGL while still targeting Direct3D on Windows.

For TCP/IP and general non-ui functionality, you should be using Qt - it makes life very easy. For 3D, you'll be using OpenGL directly via Qt-provided wrappers. You can then choose between OpenGL and ANGLE builds of Qt to decide whether you use the platform OpenGL driver directly, or whether you're using OpenGL implemented on top of DirectX (ANGLE). Since you use physx, you already have good nvidia drivers, and a decent implementation of OpenGL, so not using ANGLE is preferred. That's how I see it.