class	Particle{
	PVector		pos;
	PVector		speed;
	int			col;

	int			circular_nb;
	int			circular_id;		// the id in the circular buffer
	PVector[]	circular_pos;
	boolean		draw_previous;
	float		slow_distance;


	// pour pouvoir faire les trainer il faudrait retenir les position precedente
	// avoir un beffer tournant
	// retenir l'index actuel


	void	init_circular(int nb_previous, boolean previous_drawing){
		draw_previous = previous_drawing;
		circular_nb = nb_previous;
		circular_id = 0;
		circular_pos = new PVector[circular_nb];
		for (int i = 0; i < circular_pos.length; i++){
			circular_pos[i] = new PVector(pos.x, pos.y, 0);
		}
	}

	void	init_particle(){
		pos = new PVector(random(50, 750), random(50, 70));
		speed = new PVector(0, 0, 0);
		col = getColInt(255, 255, 255);
	
		slow_distance = 0.03;
	}

	Particle(){
		init_particle();
		init_circular(1, false);
	}

	Particle(int nb_previous){
		init_particle();
		init_circular(nb_previous, true);
	}

	void	update_position(Attractor[] attractors){
		for	(Attractor att : attractors){
			if (!att.is_active)
				continue;
			PVector d = vecSub(att.pos, pos);
			float	dist = sqrt(d.x * d.x + d.y * d.y);
			float	factor = att.weight * 1.0 / (dist + 10);

			normalize(d);

			speed.x += d.x * factor;
			speed.y += d.y * factor;

			float	cross = cross_product(getNormalized(speed), d);
			// limitation de l'eloignement
			if (cross < 0){
				speed.x *= 1.0 - (slow_distance * abs(cross));
				speed.y *= 1.0 - (slow_distance * abs(cross));
			}

			pos.x += speed.x;
			pos.y += speed.y;

			circular_id = (circular_id + 1) % circular_pos.length;
			circular_pos[circular_id].x = float(int(pos.x));
			circular_pos[circular_id].y = float(int(pos.y));
		}
	}

	void	draw(){
		//println("hello im drowing:", pos);
		if (draw_previous){
			int		id;
			Point[]	previous_pos = new Point[circular_pos.length];
			for (int i = 0; i < circular_pos.length; i++){
				id = (circular_id - i + circular_pos.length) % circular_pos.length;
				previous_pos[i] = new Point(int(circular_pos[id].x), int(circular_pos[id].y), getColInt(0, 255, 0));
			}
			//println("plop");
			laser_frame.add_line(previous_pos);
		}
		else
			laser_frame.add_line(create_point(pos, getColInt(0, 255, 0)));
	}
}

Point[]	create_point(PVector pos, int col){
	Point[]	point = new Point[2];
	
	point[0] = new Point(int(pos.x), int(pos.y), col);
	point[1] = new Point(int(pos.x+1), int(pos.y+1), col);
	return point;
}