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Diffstat (limited to 'src/crepe/manager/LoopTimerManager.h')
| -rw-r--r-- | src/crepe/manager/LoopTimerManager.h | 163 |
1 files changed, 163 insertions, 0 deletions
diff --git a/src/crepe/manager/LoopTimerManager.h b/src/crepe/manager/LoopTimerManager.h new file mode 100644 index 0000000..84178eb --- /dev/null +++ b/src/crepe/manager/LoopTimerManager.h @@ -0,0 +1,163 @@ +#pragma once + +#include <chrono> + +#include "Manager.h" + +namespace crepe { + +/** + * \brief Manages timing and frame rate for the game loop. + * + * The LoopTimerManager class is responsible for calculating and managing timing functions + * such as delta time, frames per second (FPS), fixed time steps, and time scaling. It ensures + * consistent frame updates and supports game loop operations, such as handling fixed updates + * for physics and other time-sensitive operations. + */ +class LoopTimerManager : public Manager { +public: + LoopTimerManager(Mediator & mediator); + /** + * \brief Get the current delta time for the current frame. + * + * \return Delta time in seconds since the last frame. + */ + double get_delta_time() const; + + /** + * \brief Get the current game time. + * + * \note The current game time may vary from real-world elapsed time. It is the cumulative + * sum of each frame's delta time. + * + * \return Elapsed game time in seconds. + */ + double get_current_time() const; + + /** + * \brief Set the target frames per second (FPS). + * + * \param fps The desired frames rendered per second. + */ + void set_target_fps(int fps); + + /** + * \brief Get the current frames per second (FPS). + * + * \return Current FPS. + */ + int get_fps() const; + + /** + * \brief Get the current time scale. + * + * \return The current time scale, where (0 = pause, < 1 = slow down, 1 = normal speed, > 1 = speed up). + * up the game. + */ + double get_time_scale() const; + + /** + * \brief Set the time scale. + * + * time_scale is a value that changes the delta time that can be retrieved using get_delta_time function. + * + * \param time_scale The desired time scale (0 = pause, < 1 = slow down, 1 = normal speed, > 1 = speed up). + */ + void set_time_scale(double time_scale); + + /** + * \brief Get the scaled fixed delta time om seconds. + * + * The fixed delta time is used for operations that require uniform time steps, + * such as physics calculations, and is scaled by the current time scale. + * + * \return The fixed delta time, scaled by time scale, in seconds. + */ + double get_fixed_loop_interval() const; + + /** + * \brief Get the fixed delta time in seconds without scaling by the time scale. + * + * This value is used in the LoopManager to determine how many times + * the fixed_update should be called within a given interval. + * + * \return The unscaled fixed delta time in seconds. + */ + double get_fixed_delta_time() const; + + /** + * \brief Set the fixed_delta_time in seconds. + * + * \param ms fixed_delta_time in seconds. + * + * The fixed_delta_time value is used to determine how many times per second the fixed_update and process_input functions are called. + */ + void set_fixed_delta_time(int seconds); + +private: + friend class LoopManager; + + /** + * \brief Start the loop timer. + * + * Initializes the timer to begin tracking frame times. + */ + void start(); + /** + * \brief Enforce the frame rate limit. + * + * Ensures that the game loop does not exceed the target FPS by delaying frame updates as + * necessary. + */ + void enforce_frame_rate(); + /** + * \brief Get the accumulated lag in the game loop. + * + * Lag represents the difference between the target frame time and the actual frame time, + * useful for managing fixed update intervals. + * + * \return Accumulated lag in seconds. + */ + double get_lag() const; + + /** + * \brief Update the timer to the current frame. + * + * Calculates and updates the delta time for the current frame and adds it to the cumulative + * game time. + */ + void update(); + + /** + * \brief Advance the game loop by a fixed update interval. + * + * This method progresses the game state by a consistent, fixed time step, allowing for + * stable updates independent of frame rate fluctuations. + */ + void advance_fixed_update(); + +private: + //! Target frames per second + int target_fps = 50; + //! Actual frames per second + int actual_fps = 0; + //! Time scale for speeding up or slowing down the game (0 = pause, < 1 = slow down, 1 = normal speed, > 1 = speed up) + double time_scale = 1; + //! Maximum delta time in seconds to avoid large jumps + std::chrono::duration<double> maximum_delta_time{0.25}; + //! Delta time for the current frame in seconds + std::chrono::duration<double> delta_time{0.0}; + //! Target time per frame in seconds + std::chrono::duration<double> frame_target_time + = std::chrono::duration<double>(1.0) / target_fps; + //! Fixed delta time for fixed updates in seconds + std::chrono::duration<double> fixed_delta_time = std::chrono::duration<double>(1.0) / 50.0; + //! Total elapsed game time in seconds + std::chrono::duration<double> elapsed_time{0.0}; + //! Total elapsed time for fixed updates in seconds + std::chrono::duration<double> elapsed_fixed_time{0.0}; + //! Time of the last frame + std::chrono::steady_clock::time_point last_frame_time; +}; + +} // namespace crepe |