public void setFacingVelocity(boolean followVelocity) {
        this.facingVelocity = followVelocity;
    }
Set to true if particles spawned should face
their velocity (or direction to which they are moving towards).

<p>This is typically used for e.g. spark effects.

@param followVelocity True if particles spawned should face their velocity.
jme3-core/src/main/java/com/jme3/effect/ParticleEmitter.java