/// <summary>
        /// start test world
        /// </summary>
        public void initializeSphereTest(UnityLevelController levelController)
        {
            players[0] = new Player();
            Coordinate chunkBounds = (10, 10, 10);
            Coordinate spawn       = (
                chunkBounds.x * Chunk.Diameter / 2,
                5,
                chunkBounds.x *Chunk.Diameter / 2
                );

            activeLevel = new ColumnLoadedLevel <VoxelDictionary>(
                chunkBounds,
                new SphereSource(50, spawn),
                new MarchGenerator()
                );

            levelController.level = activeLevel;
            levelController.initialize();
            listeningObservers.Add(levelController);
            activeLevel.initializeAround(spawn / Chunk.Diameter);
        }
        /// <summary>
        /// start test world
        /// </summary>
        public void initializeTestWorld(UnityLevelController levelController, IVoxelSource terrainSource)
        {
            players[0] = new Player();
            Coordinate chunkBounds = (1000, 20, 1000);

            activeLevel = new ColumnLoadedLevel <VoxelDictionary>(
                chunkBounds,
                terrainSource,
                new MarchGenerator()
                );

            Coordinate spawn = (
                chunkBounds.x * Chunk.Diameter / 2,
                chunkBounds.y *Chunk.Diameter / 2,
                chunkBounds.z *Chunk.Diameter / 2
                );

            levelController.level = activeLevel;
            levelController.initialize();
            listeningObservers.Add(levelController);
            activeLevel.initializeAround(spawn / Chunk.Diameter);
        }