[LibGDX] How on earth do I limit drawing to a certain area of the screen?

I’ve posted this on the LibGDX forum but no luck so far so maybe someone here can help?

I’ve been trying to work out how I can set my game up so that it will only render to a certain area of the application window as illustrated in the mockup-image, but im not sure which classes to look at (camera, viewport, stage?). Currently when I enlarge the application window it will just draw more of the game world since I’m using a ScreenViewport. I don’t want to just draw the world over the whole screen and then draw gui to cover since that will be too slow, I want to adjust something so that it crops all my game world drawing commands.

Will I have to place some kind of drawing surface into a gui table cell, or can it be done by just using the camera and viewport appropriately?
(note: I’m not currently using the gui table features, but I would like to integrate it now)

*Everything I try ends up stretching the draw area to fill the whole window,
*using Gdx.gl.glViewport(0, 50, 600, 600); each frame kinda works, but if the window then changes size it appears that something is trying to correct aspect ratio.
*Trying to create my own “CustomViewport extends Viewport” doesnt seem to give me any options to limit the viewport size (even though Viewport contains variables which indicate that they are for setting the size and position).

This seems like it should be much simpler since there are many instances when you would want to draw in only a specific area :clue: