Message Boards Message Boards

[GIF] Cube Life (Stereographic projection of rotating cube vertices)

Stereographic projection of rotating cube vertices

Cube Life

The basic idea is simple: I'm rotating the cube around the axis $(1,1,0)$ and stereographically projecting the vertices to the plane. Or rather, I'm thinking of the vertices of this rotating cube as the centers of spherical circles of radius $0.2$, and then stereographically projecting those circles to the plane, resulting in circles of different radii.

This stereographic projection of circles is accomplished using the ProjectedSphericalCircle function, the (gross) definition of which you can see on the post for Small Changes.

As is so often the case, I'm using the smootheststep function for easing:

smootheststep[t_] := -20 t^7 + 70 t^6 - 84 t^5 + 35 t^4;

Here's the code. The piecewise definition of $\theta$ (for some reason I used Which rather than Piecewise) is due to the fact that we need to rotate the cube by slightly different amounts between each of the pauses.

DynamicModule[{poly = "Cube", p, e, rp, ?,
  cols = RGBColor /@ {"#008cbc", "#007500", "#e6c700", "#db2f27", "#f7f7f7"}},
 p = Normalize /@ PolyhedronData[poly, "VertexCoordinates"];
 e = PolyhedronData[poly, "EdgeIndices"];
 Manipulate[
  Which[
   0 <= Mod[t, 4] < 1, ? = smootheststep[t - Floor[t]] ArcCos[1/Sqrt[3]],
   1 <= Mod[t, 4] < 2, ? = ArcCos[1/Sqrt[3]] + 
     smootheststep[t - Floor[t]] (?/2 - ArcCos[1/Sqrt[3]]),
   2 <= Mod[t, 4] < 3, ? = ?/2 + 
     smootheststep[t - Floor[t]] (?/2 - ArcCos[1/Sqrt[3]]),
   3 <= Mod[t, 4] < 4, ? = ? - 
     smootheststep[1 + Floor[t] - t] ArcCos[1/Sqrt[3]]];
  rp = p.RotationMatrix[-?, {1, 1, 0}].RotationMatrix[
     4.5 ?/12 (Floor[t] + smootheststep[Mod[t, 1]]), {0, 0, 1}];
  Graphics[
   {Blend[
     Append[cols[[;; -2]], cols[[1]]], (Floor[t] + smootheststep[Mod[t, 1]])/16],
    ProjectedSphericalCircle[#, .2] & /@ rp},
   PlotRange -> 3.52968, ImageSize -> 540, Background -> cols[[-1]]],
  {t, 0., 16}]
 ]

enter image description here - Congratulations! This post is now featured in our Staff Pick column as distinguished by a badge on your profile of a Featured Contributor! Thank you, keep it coming!

POSTED BY: EDITORIAL BOARD
Reply to this discussion
Community posts can be styled and formatted using the Markdown syntax.
Reply Preview
Attachments
Remove
or Discard

Group Abstract Group Abstract