public void setShadowZFadeLength(float length) {
        if (length == 0) {
            fadeInfo = null;
            fadeLength = 0;
            postshadowMat.clearParam("FadeInfo");
        } else {
            if (zFarOverride == 0) {
                fadeInfo = new Vector2f(0, 0);
            } else {
                fadeInfo = new Vector2f(zFarOverride - length, 1.0f / length);
            }
            fadeLength = length;
            postshadowMat.setVector2("FadeInfo", fadeInfo);
        }
    }
Define the length over which the shadow will fade out when using a
shadowZextend This is useful to make dynamic shadows fade into baked
shadows in the distance.

@param length the fade length in world units
jme3-core/src/main/java/com/jme3/shadow/PssmShadowRenderer.java