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#pragma once
#include "StarList.hpp"
namespace Star {
// Monitors the rate at which 'tick()' is called in wall-clock seconds.
class TickRateMonitor {
public:
// 'window' controls the dropoff at which 'rate' will approach zero if tick
// is not called, measured in seconds.
TickRateMonitor(double window);
double window() const;
// Resets to a zero tick-rate state
void reset();
// Ticks the given number of times, returns the current rate.
double tick(unsigned count = 1);
// Returns the rate as of the *current* time, not the time of the last tick.
double rate() const;
private:
void dropOff(double currentTime);
double m_window;
double m_lastTick;
double m_ticks;
};
// Helps tick at as close as possible to a given tick rate
class TickRateApproacher {
public:
TickRateApproacher(double targetTickRate, double window);
// The TickRateMonitor window influences how long the TickRateApproacher will
// try and speed up or slow down the tick rate to match the target tick rate.
// It should be chosen so that it is not so short that the actual target rate
// drifts, but not too long so that the rate returns to normal quickly enough
// with outliers.
double window() const;
// Setting the window to a new value will reset the TickRateApproacher
void setWindow(double window);
double targetTickRate() const;
void setTargetTickRate(double targetTickRate);
// Resets such that the current tick rate is assumed to be perfectly at the
// target.
void reset();
double tick(unsigned count = 1);
double rate() const;
// How many ticks we currently should perform, so that if each tick happened
// instantly, we would be as close to the target tick rate as possible. If
// we are ahead, may be negative.
double ticksBehind();
// The negative of ticksBehind, is positive for how many ticks ahead we
// currently are.
double ticksAhead();
// How much spare time we have until the tick rate will begin to be behind
// the target tick rate.
double spareTime();
private:
TickRateMonitor m_tickRateMonitor;
double m_targetTickRate;
};
};
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