The interpolation modes essentially set the shape of your trail (if shrinking is enabled).
Note that quadraticFlipped( f(x) = - (x-1)*(x-1) + 1) is not in the current source, because it is (too?) similar to the root interpolation (but slightly faster, root is already a really bad approximation). It can also be added or replace root.
![Image](https://www.dropbox.com/s/aokhs76gsiqrnmh/interpolationsLowRez.png?raw=1)
Full rez:https://www.dropbox.com/s/h8kg9c2r3vz1o ... s.png?dl=0
Once this scene node is included in Irrlicht, I will start on doing the rest of the work (extra features like bone attachment, etc), so it is not too much at one time.