antistellate polygons

In Openscad, there’s this site:

http://kitwallace.co.uk/3d/solid-index.xq

through which “anti-stellations” in this case
an anti-stellated dodecahedron can be created.


It is what it’s name suggests, the opposite
of stellate. Rather than points expanding outward,
in this case it’s points expanding inward.

On any polygon it would be possible to Alt-P (in Edit mode)
to create a collection of points converging in the center of
a face. Is there a way using, I don’t know, inset, extrude, or
the G command in conjuction with other settings to select
similar faces and pull them inward rather than outward to
create such an anti-stellation in Blender comparable to what’s
shown?

I know it can be done in Openscad. How do you do the
same in Blender? Or can you?

Just curious.

  1. Create a dodecahedron. For example, using the Add Mesh: Extra Objects add-on: Add -> Mesh -> Math Functions -> Solid, select Dodecahedron as Source in operator options. Go to edit mode, switch to edge selection, select an edge inside a pentagon (the one that separates a quad and a triangle), Select -> Select Similar -> Face Angles. This will select all such edges. Now from the delete menu choose “Dissolve Edges”. This will leave you with a dodecahedron made out of five-sided ngons.

  2. Select all, activate Inset Faces tool (default hotkey I). Escape out of it, open operator options, check “Individual” and adjust the Thickness to your liking.

  3. With smaller pentagons still selected, poke them (Alt+P).

  4. Switch to vertex mode, shrink selection (Select -> Less).

This should leave you with only the “poked” vertices selected, which you can now scale inwards or outwards.

http://www.pasteall.org/pic/show.php?id=88883

Yes we do.
Alt-s and Extra Objects are the keywords.

I think I figured out Stan’s directions.

Eppo, playing with Alt-S, I get some really
unusual and interesting results but, nothing
that mirrors your example.

File attached.

now_what_blend.blend (420 KB)

Question:

Dodecahedron
Edit Mode
Select All -
Del - Limited Dissolve
Alt P
A - Unselect all
Vertex Select - Select Center Vertex
Select Similar -
Amount of Adjacent Faces

S - Scale

Same thing? Or no?

Also noticed that, applying Alt - S it gets me to Stellation
too, which is kind of cool.

You should give Topmod a try, it’s only a two step operation, just remesh and extrude.


Got TopMod.

Thanx for that.

Will keep in mind.

Modified Corner Cutting (Remesh)

Also, hard to tell from the image, it’s “Stellated Extrusion”

There’s a LOT of Extrusion options.

Yes select similar faces then top left corner ‘stellate extrusion’ -1.00.

Tried your method on a rhombic triacontahedron (also in Math Functions / Solids / Custom).

Same settings.


Safe to say, the settings require some tinkering from one polygon
to the next?

(Fixed in Blender by using Solidify Modifier)

eppo, figured it out.

Inset was the key.

(Misunderstood your step 2, Stan)


So, here’s what I did based on Stan’s and eppo’s input:

  1. Create a Polyhedron using Mesh, Math Functions, Solids Regular or Custom
  2. Edit Mode - Delete, Limited Dissolve
  3. Inset the faces - I - I (Individual)
  4. Poke the Faces - Alt-P
  5. Unselect All - A
  6. Switch to Vertex Select
  7. Select any vertex
  8. Select Similar - Amount of Adjacent Faces
    (You may need to select - Less in some cases)
  9. Scale down - S
    (I found you might also try the Smooth Modifier, after
    the fact, to adjust the edges)

An antistellate Rhombicosidodecahedron (RID for short)
done using these methods.


<font size=“1”>Ouch, these time zones… I saw once a proposal for returning to something Flat on Three Whales or Elephants (not both species for the simplicity and Cost Estimate) for the Blender’s users.</font>

Just briefly- instead of using Inset on faces i started from Ctrl-B bevel on edges. Alt-s or s likely doesn’t matter here - in the default state (3d cursor at Origin) scaled verts will go center anyways.

Proof once again, with Blender, surprise!

There’s more than one way to get things
done.

Didn’t think to try Bevel. I was keying in
on Stan’s tutorial.

Tried Bevel with a dodecahedron. And Alt-P
after that. Couldn’t then figure out how to
“Select - Similar” the center vertex.

Not so troublesome when working with a dodecahedron
or something with few sides. The more complex the
polygon though, the more work that’s involved in that
case (unless, once again, there’s a shortcut I missed -
NOT out of the realm of possibility).

Thanx

Not sure if it makes a difference.

My Inset settings when I use it are:

Transform Orientation: Normal
Pivot Point: Individual Origins

and

Inset: Individual (Checked)

Indeed, many ways to skin a cat.

http://www.pasteall.org/pic/show.php?id=88902

Bevel, face mode, invert selection, poke, hide unselected, vertex mode, select less.

Or:

Bevel, face mode, invert selection, delete faces, edge mode, select non-manifold, pivot to individual origins, extrude, scale 0, vertex mode, remove doubles, pivot back to median point :slight_smile:

Inset Individual = hit I twice.

ramboblender, tried your method on several different polygons.

It seems to hold up.

Just wanted to put that out there.

Not sure what my problem was.

Perhaps the application of Doo Sabin.

Although, while your method is easier, it seems easier in
Blender to adjust the edge width while maintaining overall
object integrity.

Course once that’s done in Blender, it’s always possible to
export to OBJ and finish it up in Top Mod (or vice versa).

I see you like these math shapes hence I suggested topmod , not because it’s easy to make it there.
In topmod you can create some cool abstract models .

Now I give you a challenge to make this voronoi twisted torus :), are you up for it ?.


eppo, updated my process to include this:

“Inset Individual = hit I twice.”

Thanx