Implementing a Pause/Resume System with Custom Events
How can I use custom events to implement a pause/resume system in my game?
Implementing a pause/resume system using custom events in SDL2 is a great way to manage game state. Here's how you can do it:
Step 1: Define Custom Events
First, let's define our custom events for pausing and resuming:
#pragma once
#include <SDL.h>
namespace UserEvents {
const inline Uint32 PAUSE_GAME{
SDL_RegisterEvents(1)};
const inline Uint32 RESUME_GAME{
SDL_RegisterEvents(1)};
}Step 2: Create a Game State Manager
Next, we'll create a simple game state manager:
#include "UserEvents.h"
#include <SDL.h>
class GameStateManager {
private:
bool isPaused{false};
public:
void TogglePause() {
isPaused = !isPaused;
SDL_Event event;
event.type = isPaused
? UserEvents::PAUSE_GAME
: UserEvents::RESUME_GAME;
SDL_PushEvent(&event);
}
bool IsPaused() const { return isPaused; }
};Step 3: Handle Custom Events in Main Loop
Now, let's modify our main game loop to handle these events:
#include "GameStateManager.h"
#include "UserEvents.h"
#include <SDL.h>
#include <iostream>
int main(int argc, char* argv[]) {
SDL_Init(SDL_INIT_EVERYTHING);
GameStateManager gameState;
SDL_Event event;
bool quit{false};
while (!quit) {
while (SDL_PollEvent(&event)) {
if (event.type == SDL_QUIT) {
quit = true;
} else if (event.type == SDL_KEYDOWN &&
event.key.keysym.sym ==
SDLK_p) {
gameState.TogglePause();
} else if (event.type ==
UserEvents::PAUSE_GAME) {
std::cout << "Game Paused\n";
// Pause game logic here (e.g., stop
// timers, music, etc.)
} else if (event.type ==
UserEvents::RESUME_GAME) {
std::cout << "Game Resumed\n";
// Resume game logic here
}
}
if (!gameState.IsPaused()) {
// Update game state
// Render game
} else {
// Render pause menu
}
}
SDL_Quit();
return 0;
}This system allows you to pause and resume the game using the 'P' key. When the game is paused, the main update and render loop is skipped, effectively freezing the game state.
By using custom events, you can easily extend this system. For example, you could add a SHOW_PAUSE_MENU event to display a pause menu, or a SAVE_GAME_STATE event to save the game when pausing. This event-driven approach provides a flexible and extensible way to manage your game's pause/resume functionality.
Creating Custom Events
Learn how to create and manage your own game-specific events using SDL's event system.