Reaction to Mouse Down Events

procedure mouseButtonDown (x, y : integer);
var
	bptr : Ball;
begin
		(* give the cue ball some energy *)
	CueBall.energy := 20.0;
		(* and a direction *)
	CueBall.setDirection(hitAngle (cueBall.x - x, cueBall.y - y));
		(* then update as long as any ball moves *)
	ballMoved := true;
	while ballMoved do begin
		ballMoved := false;
		bptr := listOfBalls;
		while bptr <> nil do begin
			bptr.update;
			bptr := bptr.link;
		end;
	end;
end;

Intro OOP, Chapter 6, Slide 9