Simple FPS Counter

FPS.h

#ifndef __FPS_H__
#define __FPS_H__

// FPS Counter class
// Keep an instance in the main app context, and call update every frame
// Use the () operator to get the current FPS

class FPSCounter {
private:
	unsigned long _frames = 0;
	float _dt = 0.0f;
	float _fps = 0.0f;

public:
	// dt: time passed since last frame
	// rate: how many times to update FPS per second
	void update(double dt, float rate = 5.0f) {
		++_frames;
		_dt += (float)dt * 0.001f;
		if (_dt > 1.0f / rate) {
			_fps = _frames / _dt;
			_dt -= 1.0f / rate;
			_frames = 0;
		}
	}

	float operator()() const { return _fps; }
};

#endif