#ifndef MAIN_TIMER_SYNC_H #define MAIN_TIMER_SYNC_H /* main_timer_sync.h */ /* This file is part of: */ /* PANDEMONIUM ENGINE */ /* https://godotengine.org */ /* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur. */ /* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md). */ /* */ /* Permission is hereby granted, free of charge, to any person obtaining */ /* a copy of this software and associated documentation files (the */ /* "Software"), to deal in the Software without restriction, including */ /* without limitation the rights to use, copy, modify, merge, publish, */ /* distribute, sublicense, and/or sell copies of the Software, and to */ /* permit persons to whom the Software is furnished to do so, subject to */ /* the following conditions: */ /* */ /* The above copyright notice and this permission notice shall be */ /* included in all copies or substantial portions of the Software. */ /* */ /* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */ /* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */ /* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/ /* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */ /* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */ /* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */ /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ #include "core/config/engine.h" // define these to get more debugging logs for the delta smoothing //#define PANDEMONIUM_DEBUG_DELTA_SMOOTHER struct MainFrameTime { float idle_step; // time to advance idles for (argument to process()) int physics_steps; // number of times to iterate the physics engine float interpolation_fraction; // fraction through the current physics tick void clamp_idle(float min_idle_step, float max_idle_step); }; class MainTimerSync { class DeltaSmoother { public: // pass the recorded delta, returns a smoothed delta int64_t smooth_delta(int64_t p_delta); private: void update_refresh_rate_estimator(int64_t p_delta); bool fps_allows_smoothing(int64_t p_delta); // estimated vsync delta (monitor refresh rate) int64_t _vsync_delta = 16666; // keep track of accumulated time so we know how many vsyncs to advance by int64_t _leftover_time = 0; // keep a rough measurement of the FPS as we run. // If this drifts a long way below or above the refresh rate, the machine // is struggling to keep up, and we can switch off smoothing. This // also deals with the case that the user has overridden the vsync in the GPU settings, // in which case we don't want to try smoothing. static const int MEASURE_FPS_OVER_NUM_FRAMES = 64; int64_t _measurement_time = 0; int64_t _measurement_frame_count = 0; int64_t _measurement_end_frame = MEASURE_FPS_OVER_NUM_FRAMES; int64_t _measurement_start_time = 0; bool _measurement_allows_smoothing = true; // we can estimate the fps by growing it on condition // that a large proportion of frames are higher than the current estimate. int32_t _estimated_fps = 0; int32_t _hits_at_estimated = 0; int32_t _hits_above_estimated = 0; int32_t _hits_below_estimated = 0; int32_t _hits_one_above_estimated = 0; int32_t _hits_one_below_estimated = 0; bool _estimate_complete = false; bool _estimate_locked = false; // data for averaging the delta over a second or so // to prevent spurious values int64_t _estimator_total_delta = 0; int32_t _estimator_delta_readings = 0; void made_new_estimate() { _hits_above_estimated = 0; _hits_at_estimated = 0; _hits_below_estimated = 0; _hits_one_above_estimated = 0; _hits_one_below_estimated = 0; _estimate_complete = false; #ifdef PANDEMONIUM_DEBUG_DELTA_SMOOTHER print_line("estimated fps " + itos(_estimated_fps)); #endif } } _delta_smoother; // wall clock time measured on the main thread uint64_t last_cpu_ticks_usec; uint64_t current_cpu_ticks_usec; // logical game time since last physics timestep float time_accum; // current difference between wall clock time and reported sum of idle_steps float time_deficit; // number of frames back for keeping accumulated physics steps roughly constant. // value of 12 chosen because that is what is required to make 144 Hz monitors // behave well with 60 Hz physics updates. The only worse commonly available refresh // would be 85, requiring CONTROL_STEPS = 17. static const int CONTROL_STEPS = 12; // sum of physics steps done over the last (i+1) frames int accumulated_physics_steps[CONTROL_STEPS]; // typical value for accumulated_physics_steps[i] is either this or this plus one int typical_physics_steps[CONTROL_STEPS]; int fixed_fps; protected: // returns the fraction of p_frame_slice required for the timer to overshoot // before advance_core considers changing the physics_steps return from // the typical values as defined by typical_physics_steps float get_physics_jitter_fix(); // gets our best bet for the average number of physics steps per render frame // return value: number of frames back this data is consistent int get_average_physics_steps(float &p_min, float &p_max); // advance physics clock by p_idle_step, return appropriate number of steps to simulate MainFrameTime advance_core(float p_frame_slice, int p_physics_ticks_per_second, float p_idle_step); // calls advance_core, keeps track of deficit it adds to animaption_step, make sure the deficit sum stays close to zero MainFrameTime advance_checked(float p_frame_slice, int p_physics_ticks_per_second, float p_idle_step); // determine wall clock step since last iteration float get_cpu_idle_step(); public: MainTimerSync(); // start the clock void init(uint64_t p_cpu_ticks_usec); // set measured wall clock time void set_cpu_ticks_usec(uint64_t p_cpu_ticks_usec); //set fixed fps void set_fixed_fps(int p_fixed_fps); // advance one frame, return timesteps to take MainFrameTime advance(float p_frame_slice, int p_physics_ticks_per_second); }; #endif // MAIN_TIMER_SYNC_H