In today's post, we're examining the pause functionality of the LucKey Park game code, which is built on the 'Dry' engine. We'll uncover how the game's status is managed and toggled, especially in response to the cancel button (ESC key), and provide insights into the game's input handling and state management.
Understanding the Game's Status Management
The 'Park' game uses an enumeration GameStatus with values like GS_MAIN, GS_PLAY, GS_PAUSED, and GS_MODAL to represent the game's current state. The Game class in game.h maintains a status_ variable to track this state.
enum GameStatus{ GS_MAIN, GS_PLAY, GS_PAUSED, GS_MODAL };
class Game: public Object
{
// ...
private:
GameStatus status_;
};
The Game class provides methods to get and set this status, as well as a TogglePause() method that switches between GS_PLAY and GS_PAUSED.
Binding the Cancel Action
In inputmaster.cpp, the InputMaster class binds the IA_CANCEL action to the ESC key. This setup is crucial for handling the pause functionality when the player presses ESC.
Bind(IA_CANCEL, KEY_ESCAPE);
Handling the Cancel Action
When the IA_CANCEL action is triggered, the HandleAction method in InputMaster responds accordingly. If no tool is active, it calls gui->ShowMainMenu(), which indirectly pauses the game by changing the game's status.
case IA_CANCEL:
if (tool) sceneCursor->SetTool(nullptr);
else gui->ShowMainMenu();
break;
The Main Update Loop Controlled by Dry Engine
The Dry engine, like its predecessor Urho3D, manages the main game loop internally. Developers hook into this loop by subscribing to the E_UPDATE event, which the engine dispatches every frame. This event allows developers to perform per-frame updates to their game logic.
While the main update loop is not explicitly shown in the provided snippets, it's typically where the game checks the status_ variable each frame. If the status is GS_PAUSED or GS_MODAL, the loop skips updating the game world, pausing the game's logic.
End-to-End Pause Functionality
From the moment the player presses the ESC key to the game entering a paused state, the flow is as follows:
- The ESC key is pressed.
- InputMaster detects the IA_CANCEL action.
- HandleAction calls gui->ShowMainMenu() if no tool is active.
- ShowMainMenu() sets the game's status to GS_MODAL.
- The main update loop, controlled by the Dry engine, respects this status and pauses the game.
This exploration has provided a clear understanding of how the pause functionality is implemented in Lucky Park using the Dry engine. It's a great example of how game state management and input handling work together to create responsive gameplay.
Stay tuned for more deep dives into game development.