I'm planning to add an interactive 3D model to my application. 3D objects of model should be rotated and moved within C++ code. The whole model is also subject to change during calculations. It also should be a widget in the main window (not a separate window). Objects are in STEP format, but we can convert them to any other needed format if needed.
There are many APIs / Tools / Libraries which I can't find which one is suitable for my application. I'm looking for suggestions or a start point.
Platform: Linux/Windows
Toolchain: C++ / Qt 4 and 5 / OpenGL