@Override
    public void write(JmeExporter ex) throws IOException {
        super.write(ex);
        OutputCapsule oc = ex.getCapsule(this);
        oc.write(normalVelocity, "normalVelocity", 0.0f);
        oc.write(surfaceTangentFactor, "surfaceTangentFactor", 0.0f);
        oc.write(surfaceTangentRotation, "surfaceTangentRotation", 0.0f);
    }
This method returns the surface tangent rotation factor.
@return the surface tangent rotation factor
jme3-core/src/main/java/com/jme3/effect/influencers/NewtonianParticleInfluencer.java