How do I make it so that with your mouse it is possible to direct an airplane like so: Steambirds (http://www.steambirds.com/)? How do I compute and draw the black line that you make to move the airplane?
What you’ll want is a spline, probably a bezier curve as they are fairly easy to implement, if I get some time I’ll dig up my code on it.
Anyway here’s some stuff to get you started.
http://mathworld.wolfram.com/BezierCurve.html
You should be able to achieve what you want with only three points.