Flatland

In Edwin Abbott’s 1884 story, a Square lives in a world with only two dimensions. When a Sphere passes through, the Square sees a circle appear from nowhere, grow, shrink and vanish.

Every visitor here is a solid from the third dimension, but Flatlanders can only ever see its slice: the place where it crosses their plane. Push a solid through the page and watch the slice change, then unlock the view to see the whole thing.

Select a Flatlander and look through its eye. In Flatland everything is seen edge-on, as a single line, and distance shows only as fog.

• Drag a shape from the palette onto the page.
• Drag a Flatlander to lift it out of its world. Its neighbours can’t see where it went.
• Drag a slice to move its solid. Drag the side view to push it up or down.
• Unlock the view, then drag to look around and scroll to zoom.