private Vector3f getTranslationForFrame(int keyFrameIndex) {
        if (keyFrameIndex < 0 || keyFrameIndex > totalFrames) {
            throw new ArrayIndexOutOfBoundsException("keyFrameIndex must be between 0 and " + totalFrames + " (received " + keyFrameIndex + ")");
        }
        Vector3f v = keyFramesTranslation[keyFrameIndex];
        if (v == null) {
            v = new Vector3f();
            keyFramesTranslation[keyFrameIndex] = v;
        }
        return v;
    }
returns the translation for a given frame index
creates the translation if it doesn't exist
@param keyFrameIndex index
@return the translation
jme3-core/src/main/java/com/jme3/animation/AnimationFactory.java