public void setRange(float range) {
        this.range = range;
    }
Generate a random value to add  to the computed average
@param random the random generator
@param offsetRange
@param coords
@param average
@return A semi-random value within offsetRange
jme3-terrain/src/main/java/com/jme3/terrain/heightmap/MidpointDisplacementHeightMap.java