When it comes to developing video games, physics simulations play a crucial role in creating realistic and immersive experiences. Traditionally, physics simulations were handled on the CPU using multiple threads. However, with the advent of the C++20 standard, we now have a new threading facility called std::jthread that provides a more elegant and convenient way to handle multithreading in our games.

What is std::jthread?

std::jthread is a new addition to the C++ standard library in the C++20 release. It stands for “joining thread” and is an enhancement over std::thread. Unlike its predecessor, std::jthread automatically joins when the thread object is destroyed, making it easier to handle thread shutdown and resource management.

Using std::jthread for Physics Simulations

In a video game, physics simulations often involve performing calculations on a separate thread to offload the CPU-intensive work from the main game loop. Let’s take a look at how we can utilize std::jthread for a physics simulation in a game:

void physicsSimulation()
{
    // Perform physics calculations here
    // ...

    // Update game state based on physics calculations
    // ...
}

int main()
{
    // Initialize game components

    std::jthread physicsThread(&physicsSimulation);

    while (gameRunning)
    {
        // Process user input
        // ...

        // Update game logic
        // ...

        // Render graphics
        // ...

        // Wait for the physics simulation to complete
        physicsThread.join();
        physicsThread = std::jthread(&physicsSimulation);
    }

    // Cleanup and exit
    // ...
}

In the example above, we have a physicsSimulation function that performs the physics calculations for our game. We create a std::jthread object physicsThread and pass the physicsSimulation function as its constructor argument.

Within the game loop, we wait for the physics simulation to complete by calling physicsThread.join(). This ensures that the main game loop won’t continue until the physics thread has finished its calculations. After joining, we create a new std::jthread with the physicsSimulation function to start the next physics simulation.

By using std::jthread, we can easily manage the lifecycle of the physics simulation thread in a more intuitive way. The automatic joining behavior ensures that we don’t need to explicitly join or detach the thread manually, making our code cleaner and less prone to resource leaks.

Conclusion

The introduction of std::jthread in C++20 provides a convenient mechanism for handling multithreading in video game physics simulations. By utilizing std::jthread, we can offload CPU-intensive physics calculations to separate threads, leading to improved performance and responsiveness in our games.

#gameDev #physicsSimulations