Hello,
I am quite noob in 3D simulation and I am trying to build a simple train moving along a curved track. In a simple scenario, I am receiving two lines, defined by starting point, bend point(s) and a ending point. What I would like to do is to compute a bezier curve using the mentioned points and use them to build a spline.
Then, I would like to use the spline for a curved geometry and a motion path following that curve. Can you give me some hints on how to do this?
Many thanks! 
Bezier Curve interpolation doesn’t work properly with motion path. it’s a bug yet to fix.
You should use catmull-rom interpolation it works fine and easier to control, because unlike bezier, catmul-rom spline go through all their control points.
resources are https://code.google.com/p/jmonkeyengine/source/browse/trunk/engine/src/test/jme3test/animation/TestMotionPath.java
and https://code.google.com/p/jmonkeyengine/source/browse/trunk/engine/src/test/jme3test/animation/TestCameraMotionPath.java