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