At x = 178 we are immediately before of the block at 12 h. Its red side fills our Janus circle because all light from objects in our front comes from here.
The jagged border of the checkered pattern is an artifact of the limited precision of our simple simulation.
We pass the front side in the next step.
After we have passed the red side of the block at 12 h, it is behind us and fills completely the picture outside our Janus circle because this red side covers everything which is behind us.
Ahead of us within our Janus circle lies the interior of the block at 12 h with its the green sides, the yellow back and the reddish brown top and bottom faces.
