In game development and animation, timers are essential to control the flow of events and create dynamic experiences. C++ provides the std::chrono library, which offers a high-resolution clock for accurate timing. In this blog post, we will explore how to build timers for games and animations using std::chrono.

Table of Contents

• Introduction to std::chrono
• Creating a timer
• Updating the timer
• Pausing and resuming the timer
• Conclusion

Introduction to std::chrono

std::chrono is a C++ library introduced in the C++11 standard, providing utilities for time-related operations. It offers a flexible and easy-to-use way to measure time intervals and perform calculations with time points.

The library includes different clock types, such as system_clock, steady_clock, and high_resolution_clock, each suited for specific use cases. When building timers for games and animations, the high_resolution_clock is often the best choice due to its high precision.

Creating a timer

To create a timer using std::chrono, we need to store the start time point and the duration of the timer. We can define our timer class and include the necessary headers:

#include <chrono>

class Timer {
public:
    using Clock = std::chrono::high_resolution_clock;
    using TimePoint = std::chrono::time_point<Clock>;

    Timer() {
        start();
    }

    void start() {
        start_time_ = Clock::now();
    }
    
private:
    TimePoint start_time_;
};

In the example above, we define a class called Timer that uses std::chrono::high_resolution_clock as the clock type. The TimePoint type represents a point in time.

The constructor of the Timer class automatically starts the timer by calling the start function, which sets the start_time_ variable to the current time using Clock::now().

Updating the timer

Next, we need to update our timer to calculate the elapsed time. We can add a member function called getElapsedTime to calculate the duration between the start time and the current time:

class Timer {
public:
    // ...

    std::chrono::milliseconds getElapsedTime() const {
        auto current_time = Clock::now();
        return std::chrono::duration_cast<std::chrono::milliseconds>(current_time - start_time_);
    }

private:
    // ...
};

The getElapsedTime function subtracts the start time from the current time and converts the duration to milliseconds using std::chrono::duration_cast.

Pausing and resuming the timer

In games and animations, it is often necessary to pause and resume timers. We can add member functions to pause and resume our timer:

class Timer {
public:
    // ...

    void pause() {
        paused_ = true;
        pause_time_ = Clock::now();
    }

    void resume() {
        if (paused_) {
            auto resume_time = Clock::now();
            start_time_ += (resume_time - pause_time_);
            paused_ = false;
        }
    }

private:
    // ...
};

The pause function sets the paused_ flag to true and saves the current time in pause_time_. The resume function checks if the timer is paused and adjusts the start time accordingly.

Conclusion

By utilizing the std::chrono library in C++, we can easily create timers for games and animations. The high-resolution clock provides accurate timing, and the various functionalities allow control over pausing and resuming the timers as needed.

Remember to check the official documentation for more details on std::chrono and its available features.

#gamedevelopment #animation