if(!FastMath.isPowerOfTwo(size)) { throw new JmeException("Size must be (2^N) sized."); }
    public MidPointHeightMap(int size, float roughness) {        if (roughness < 0 || size <= 0) {            throw new JmeException("size and roughness must be " +            	"greater than 0");        }        this.roughness = roughness;        this.size = size;                load();    }