Stepper.h

class Stepper
{
public:
	void setFps(float fps) { step_time_ = 1/fps; }
	void play() { is_playing_ = true; }
	void step() { time_counter_+=step_time_; }
	void stop() { is_playing_=false; time_counter_=0; }
	void update(float elapsed_time) {
		steps_past_ = 0;
		if(isPlaying()) {
			time_counter_ += elapsed_time;
		}
		while(time_counter_ >= step_time_) {
			time_counter_ -= step_time_;
			++steps_past_;
		}
	}
	int getNumPastSteps() const { return steps_past_; }
	bool isPlaying() const { return is_playing_; }
private:
	bool is_playing_=false;
	int steps_past_=0;
	float step_time_=1/30.;
	float time_counter_=0;
};