LibGDX中Screen、Stage、Group类适用场景及界面实现选型咨询

Hey there! Let's break down exactly how to use LibGDX's Screen, Stage, and Group for your game's UI setup—this all clicks once you match each component to its intended job.

First, let's clarify what each class does #

• Screen: Think of this as a full "page" or scene in your game. Each distinct interface (main menu, new game setup, load game, settings, gameplay) gets its own Screen. It handles lifecycle events like when the page is shown, hidden, or rendered, making it perfect for switching between major game states.
• Stage: This is your UI's workhorse—it manages all your interactive elements (buttons, sliders, checkboxes) and handles input events (clicks, drags). Every Screen will almost always have at least one Stage to hold its UI components.
• Group: This is a container for grouping related UI elements together. It lets you treat a set of components as a single unit (like hiding all of them at once, or moving them as a group). Table (a subclass of Group) is especially useful here for creating clean, organized layouts.

Now let's map this to your specific interfaces #

1. Main Menu Screen

• Create a MainMenuScreen class that implements Screen. In its show() method, initialize a Stage.
• Add four TextButton actors to the Stage: "Start New Game", "Load Game", "Settings", "Exit".
• Bind click listeners to each button: e.g., clicking "Start New Game" triggers a switch to your NewGameScreen, while "Exit" calls Gdx.app.exit().

2. "Start New Game" Screen

• Make a NewGameScreen (also implementing Screen) with its own Stage.
• Use Groups to organize related controls:
  • A DifficultyGroup holding your difficulty selection (like a set of CheckBox or toggle TextButton options)
  • A PlayerCountGroup with your player number selector (e.g., a SelectBox or number input field)
• Add both groups plus a "Start" button to the Stage. The "Start" button's listener will grab the selected difficulty/player count, then switch to your gameplay Screen.

3. "Load Game" Screen

• Build a LoadGameScreen with a Stage. Use a Table (Group subclass) to list your save files neatly.
• For each save, create a small Group containing the save name, a "Load" button, and a "Delete" button. Add each of these save groups to the Table for vertical/horizontal layout.
• Bind listeners: "Load" will load the selected save and switch to gameplay; "Delete" will remove the save and refresh the list.

4. "Settings" Screen

• Create a SettingsScreen with a Stage, again using a Table for layout.
• Add your quality level SelectBox, volume Slider, plus "Apply" and "Cancel" buttons to the Table.
• "Apply" will save your settings (use Preferences for persistent storage) and return to the main menu. "Cancel" will skip saving and go back immediately.

5. Gameplay Screen

• Make a GameplayScreen with two Stages (or one Stage with nested Groups):
  • One Stage (or Group) for the panable game window: Use a Viewport (like FitViewport) to handle camera panning, and add your game world actors to this Group/Stage. You can pan the camera or move the Group to shift the view.
  • A second Stage for the overlay UI (sidebar controls, status bars): Add these actors directly to the Stage so they render on top of the game window, no matter how the game view pans.

Quick Rule of Thumb #

• Use Screen for every distinct page/scene in your game.
• Use Stage as the base container for all UI elements in a Screen (handle input and rendering here).
• Use Group (especially Table) to organize related UI components into manageable chunks.

内容的提问来源于stack exchange，提问作者Mateusz Bartkowski