I spent the greater part of today messing around with getting a pop-up menu going and have the first pass done. I also decided to bite the bullet (to a degree) and implement some placeholder graphics until I get far enough along where I can either spend more time working on better icons or hire someone to do them for me.
Here's what the pop-up menu looks like at the moment:
First off, I'm using the screen frameworks that I patterned after SuperJumper from Mario Zechner's libgdx demo suite. Part of that frameworks includes states of the screens: GAME_READY, GAME_RUNNING, GAME_PAUSED, GAME_LEVEL_END, and GAME_OVER. Under normal conditions, the state is GAME_RUNNING. This performs updates and rendering - which currently includes the Box2d renderer and Box2d world step() functions. When the user hits the menu button, the screen detects this and switches to the GAME_PAUSED screen. This halts updates to the screen (but still allows the debug renderer to execute - which keeps the background in view). Further, it's during this state that I allow the pop-menu renderer to execute.
The popup menu is a separate class that I named InGameMenu. It contains a 2d scene stage, 5 buttons, a background and a group. All the button and image items are added to a BoundGroup. The BroundGroup acts kinda like a panel or layout. Everything that it contains is locally referenced, and the group itself is referenced from the world coordinates. Therefore, I can stick a button at 0,0, and then move the group itself around without having to worry about updating the button. Pretty cool.
The popmenu also contains some simple state information indicating whether it is animating or not. I create it such that it is off to the left side of the screen. When it activates, the render() method simply increments the group's x parameter until it hits 0 -- meaning the left side of the screen. To deactivate it, the render() method decrements the group's x parameter until it hits -viewportwidth/2... meaning fully off the screen.
The background graphic is a 1 pixel high x 350 pixel wide image. I set the height to match the height of the viewport and the libgdx drivers take over rescaling it to fit.
The next bit of programming will be for me to create a scrolling pane text bit within this group (or perhaps, just switch it to another group.)
Things are starting to pick up. I really do need to implement a whole bunch of levels. The game frameworks are pretty much set. I've got tweaking to do, but it's getting close!