For a while I've been using SDL to write my 3D engine,and have recently been implementing an editor that can export an optimized format for the type of engine Im building. Right now the editor is fairly simple, objects can just be moved around and their textures and models can be changed. As of right now, I'm using SDL with OpenGL to render everything, but I want to use Qt for the GUI part of the editor, that way it looks native on every platform. I've got it working great so far, I'm running a QApplication inside of the SDL application, so it basically just opens 2 windows, one that uses SDL and OpenGL, and the other using Qt. Doing a bit of research, I've found that you can manually update a QApplication, which totally removes any threading problems, and everything works. Just in case you're having a hard time visualizing this, heres a picture:

What my goal is to merge these windows into one, because on smaller screens (like my laptop's) it makes it really hard to keep track of all the different windows that I would eventually have. I know theres a way to render to Qt with OpenGL, but can this be integrated with SDL? Am I going to need to move away from using an SDL window and use a QT one if the editor is enabled? Just to clarify, when the engine isn't in editor mode, it won't use and Qt, just SDL, so optimally I wouldn't need to do this.

Thanks.

I haven't used it yet but there is QQuickRenderControl which should allow exactly what you want, provided your UI is rendered with QML (but I personally don't want to do old-fashioned UI development since learning QML anyway).

Its absolutely possible. My project is a 2D title that uses SDL and OpenGL for graphics and has a QT map editor. We used our graphics engine in the editor build and all the rendering was done onto an QGLWidget. It worked for us pretty well. Recently, I've been doing a major redesign of our editor and have removed the use of our graphics engine from the editor and instead use QGraphicsScene/QGraphicsView to render the map instead. We didn't have any major issues with using our graphics engine and QT though.

Take a look at the QGLWIdget. I think you can just do all your SDL/OpenGL rendering to that widget, and then place the widget inside your QT application so that you can use QT for the GUI components.