godot/main/main_timer_sync.h
Hugo Locurcio 937c1a716c
Rename iterations_per_second to physics_ticks_per_second
This makes it clearer that this property is only about physics FPS,
not rendering FPS.

The `physics_fps` project setting was also renamed to
`physics_ticks_per_second` for consistency.
2021-08-11 02:37:02 +02:00

103 lines
4.8 KiB
C++

/*************************************************************************/
/* main_timer_sync.h */
/*************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
/*************************************************************************/
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/* Copyright (c) 2014-2021 Godot Engine contributors (cf. AUTHORS.md). */
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/*************************************************************************/
#ifndef MAIN_TIMER_SYNC_H
#define MAIN_TIMER_SYNC_H
#include "core/config/engine.h"
struct MainFrameTime {
double process_step; // delta time to advance during process()
int physics_steps; // number of times to iterate the physics engine
double interpolation_fraction; // fraction through the current physics tick
void clamp_process_step(double min_process_step, double max_process_step);
};
class MainTimerSync {
// wall clock time measured on the main thread
uint64_t last_cpu_ticks_usec = 0;
uint64_t current_cpu_ticks_usec = 0;
// logical game time since last physics timestep
double time_accum = 0;
// current difference between wall clock time and reported sum of process_steps
double time_deficit = 0;
// 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 = 0;
protected:
// returns the fraction of p_physics_step 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
double 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(double &p_min, double &p_max);
// advance physics clock by p_process_step, return appropriate number of steps to simulate
MainFrameTime advance_core(double p_physics_step, int p_physics_ticks_per_second, double p_process_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(double p_physics_step, int p_physics_ticks_per_second, double p_process_step);
// determine wall clock step since last iteration
double get_cpu_process_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(double p_physics_step, int p_physics_ticks_per_second);
};
#endif // MAIN_TIMER_SYNC_H