HN Explorer

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mkl
This is great! I think it really needs an undo button in the operations mode.
lifthrasiir
Also shapes can be made arbitrary smaller. For example, tetrahedron -> rectify -> rectify -> contract will result in a smaller tetrahedron.
fjfaase
Looks like you can use the back button of the browser for this. And a redo can be done by using the forward button of the browser.
aj7
Unless someone can show me how to generate a corner cube prism (one of the most technologically important prisms, and quite simple), this is coloring. I tried for a while.
gilleain
Is that a regular faced polyhedra? From a google search it seems like this is a class of shape that combines flat faces and curved ones.
aj7
It’s a cube truncated to preserve three adjacent faces. Both the solid prism and hollow (just mirror surfaces) work as practical retroreflectors. You can’t build machine tools, semiconductor processing tools, or accurately tighten the bolts that hold on a 777’s wing without them. If you have an array of them on the moon, you can measure the distance to the moon, at one instant, to an accuracy of a millimeter.
knolan
That isn’t a convex polyhedron, A retroreflective surface would actually be the interface between tessellated cubes.
Waterluvian
I love this website. Wow. I think it accumulates a bit too much browser history but not a big deal.

As a complete novice to geometry and topology, I find the classification of all kinds of types of polygons to be equal parts maddening and beautiful. It’s wild to me that we can classify what we do to any kind of geometry to get these subsets.

unclesaamm
I love this! Relatedly, here is a plug of an interactive unfolding of 4d polytopes into their 3d faces that I made recently: https://sam.zhang.fyi/html/unfolding/index.html
dabed
"Beautifully, all unfoldings of the 4-cube, 4-simplex, and 4-orthoplex are nets." why? is it a theorem or is it obvious?