Side Walls

   

Let's add some side walls. How about a purple wall on our right …

   

… and a green wall on our left?

   

We can also add a floor and ceiling.

   

In three dimensions, that's all we can do, but in four dimensions we can also add walls in the in and out directions.

   

The wall in the in direction is yellow, the one in the out direction is red.

Just for completeness, let's add one more wall, right behind us, so that we're completely enclosed. We'll have to imagine that one, since we can't see it.

When you're looking at a picture like that within the game, on a full screen and in stereo, it's easy to figure out which lines are which. Here, however, I think the lines are already a little too dense—and soon there are going to be even more of them! So, to keep things simple, let's turn off textures on the floor and ceiling and on the walls in the in and out directions, like so.

   

That's not something you can do within the game, by the way.