public void AddedEntityAmongOtherEntitiesWillBeFoundByPosition()
        {
            Entity entityInPosition;
            int    id = 1;

            WorldGrid worldGrid = new WorldGrid();
            Vector3   position  = new Vector3(0.0f, 0.0f, 0.0f);

            worldGrid.AddEntity(new Sphere(id, position, Color.Black));

            worldGrid.AddEntity(new Sphere(id + 1, new Vector3(1.0f, 0.0f, 0.0f), Color.Black));
            worldGrid.AddEntity(new Sphere(id + 2, new Vector3(0.0f, 1.0f, 0.0f), Color.Black));
            worldGrid.AddEntity(new Sphere(id + 3, new Vector3(0.0f, 0.0f, 1.0f), Color.Black));

            entityInPosition = worldGrid.GetEntityByVoxelPosition((IntVector)position);

            Assert.IsNotNull(entityInPosition, "No entity was found at the position");
            Assert.AreEqual <Vector3>(position, entityInPosition.GetPosition(), "The added and the found entity did not have the same position.");
            Assert.AreEqual <int>(id, entityInPosition.GetIndex(), "The added and the found entity did not have the same index.");
        }
        public void AddedEntityAmongNoOtherEntitiesWillNotBeFoundByWrongPosition()
        {
            Entity entityInPosition;
            int    id = 1;

            WorldGrid worldGrid = new WorldGrid();
            Vector3   position  = new Vector3(0.0f, 0.0f, 0.0f);

            worldGrid.AddEntity(new Sphere(id, position, Color.Black));

            entityInPosition = worldGrid.GetEntityByVoxelPosition(new IntVector(1, 0, 0));

            Assert.IsNull(entityInPosition);
        }