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d95794ec8a
As many open source projects have started doing it, we're removing the current year from the copyright notice, so that we don't need to bump it every year. It seems like only the first year of publication is technically relevant for copyright notices, and even that seems to be something that many companies stopped listing altogether (in a version controlled codebase, the commits are a much better source of date of publication than a hardcoded copyright statement). We also now list Godot Engine contributors first as we're collectively the current maintainers of the project, and we clarify that the "exclusive" copyright of the co-founders covers the timespan before opensourcing (their further contributions are included as part of Godot Engine contributors). Also fixed "cf." Frenchism - it's meant as "refer to / see".
103 lines
4.8 KiB
C++
103 lines
4.8 KiB
C++
/**************************************************************************/
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/* main_timer_sync.h */
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/**************************************************************************/
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/* This file is part of: */
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/* GODOT ENGINE */
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/* https://godotengine.org */
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/**************************************************************************/
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/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
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/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur. */
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/* */
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/* Permission is hereby granted, free of charge, to any person obtaining */
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/* a copy of this software and associated documentation files (the */
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/* "Software"), to deal in the Software without restriction, including */
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/* without limitation the rights to use, copy, modify, merge, publish, */
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/* distribute, sublicense, and/or sell copies of the Software, and to */
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/* permit persons to whom the Software is furnished to do so, subject to */
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/* the following conditions: */
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/* */
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/* The above copyright notice and this permission notice shall be */
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/* included in all copies or substantial portions of the Software. */
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/* */
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/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
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/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
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/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
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/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
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/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
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/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
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/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
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/**************************************************************************/
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#ifndef MAIN_TIMER_SYNC_H
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#define MAIN_TIMER_SYNC_H
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#include "core/config/engine.h"
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struct MainFrameTime {
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double process_step; // delta time to advance during process()
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int physics_steps; // number of times to iterate the physics engine
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double interpolation_fraction; // fraction through the current physics tick
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void clamp_process_step(double min_process_step, double max_process_step);
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};
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class MainTimerSync {
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// wall clock time measured on the main thread
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uint64_t last_cpu_ticks_usec = 0;
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uint64_t current_cpu_ticks_usec = 0;
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// logical game time since last physics timestep
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double time_accum = 0;
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// current difference between wall clock time and reported sum of process_steps
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double time_deficit = 0;
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// number of frames back for keeping accumulated physics steps roughly constant.
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// value of 12 chosen because that is what is required to make 144 Hz monitors
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// behave well with 60 Hz physics updates. The only worse commonly available refresh
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// would be 85, requiring CONTROL_STEPS = 17.
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static const int CONTROL_STEPS = 12;
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// sum of physics steps done over the last (i+1) frames
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int accumulated_physics_steps[CONTROL_STEPS];
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// typical value for accumulated_physics_steps[i] is either this or this plus one
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int typical_physics_steps[CONTROL_STEPS];
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int fixed_fps = 0;
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protected:
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// returns the fraction of p_physics_step required for the timer to overshoot
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// before advance_core considers changing the physics_steps return from
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// the typical values as defined by typical_physics_steps
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double get_physics_jitter_fix();
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// gets our best bet for the average number of physics steps per render frame
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// return value: number of frames back this data is consistent
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int get_average_physics_steps(double &p_min, double &p_max);
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// advance physics clock by p_process_step, return appropriate number of steps to simulate
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MainFrameTime advance_core(double p_physics_step, int p_physics_ticks_per_second, double p_process_step);
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// calls advance_core, keeps track of deficit it adds to animaption_step, make sure the deficit sum stays close to zero
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MainFrameTime advance_checked(double p_physics_step, int p_physics_ticks_per_second, double p_process_step);
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// determine wall clock step since last iteration
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double get_cpu_process_step();
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public:
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MainTimerSync();
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// start the clock
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void init(uint64_t p_cpu_ticks_usec);
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// set measured wall clock time
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void set_cpu_ticks_usec(uint64_t p_cpu_ticks_usec);
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//set fixed fps
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void set_fixed_fps(int p_fixed_fps);
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// advance one frame, return timesteps to take
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MainFrameTime advance(double p_physics_step, int p_physics_ticks_per_second);
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};
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#endif // MAIN_TIMER_SYNC_H
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