Fader.hpp

#ifndef MP_FADER_HPP
#define MP_FADER_HPP

#include <stdint.h>
#include <boost/atomic.hpp>

struct PlayerObject;

class Fader {
private:
	boost::atomic<uint16_t> cur;
	boost::atomic<uint16_t> limit;
	boost::atomic<int8_t> inc; // -1 or 1 or 0
public:
	Fader();

	// If samplerate differs, it resets.
	void change(int8_t inc /* 1 for fading in, -1 for fading out */, int Samplerate);

	void finish();
	void wait(PlayerObject* player);

	double sampleFactor() const {
		if(limit == 0) return 1;
		return double(cur) / limit;
	}

	bool finished() const {
		int8_t incCpy(inc);
		if(incCpy == 0) return true;
		if(incCpy > 0) return cur >= limit;
		if(incCpy < 0) return cur == 0;
		assert(false); return false;
	}

	struct Scope {
		Fader& fader;
		uint16_t cur, limit;
		int8_t inc;
		Scope(Fader& _fader) : fader(_fader) {
			cur = fader.cur;
			limit = fader.limit;
			inc = fader.inc;
		}
		~Scope() {
			if(inc == 0) return; // no change
			if(inc != fader.inc) return; // changed meanwhile
			if(limit != fader.limit) return; // changed meanwhile
			fader.cur = cur;
		}
		double sampleFactor() const {
			if(limit == 0) return 1;
			return double(cur) / limit;
		}
		void frameTick() {
			if(finished()) return;
			cur += inc;
		}
		bool finished() {
			if(inc == 0) return true;
			if(inc > 0) return cur >= limit;
			if(inc < 0) return cur == 0;
			assert(false); return false;
		}
	};

};


#endif // FADER_HPP