int grassLimit = height*width/2;
        int grassCount = 0;
        while (grassCount<grassLimit){
            int i = ThreadLocalRandom.current().nextInt(0,height);
            int j = ThreadLocalRandom.current().nextInt(0,width);
            if(matrix[i][j].getGroundType()!= MapTile.GroundType.WATER && matrix[i][j].getGroundType()!= MapTile.GroundType.WATER_DEEP){
                matrix[i][j].getContent().add(new Grass());
                grassCount++;
            }
        }