Scherk's second minimal surface script
 1-17  18-34

Previous
Next
 From:  bemfarmer
6524.18 In reply to 6524.17 
There is source code for SculptGen. I've no idea if it can be modified to make nurbs, or which MoI commands could do
equivalent twisting and bending...

After work I'll try to blend together the Scherk1 script output.

- Brian
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  bemfarmer
6524.19 
The Scherk1 surface can be copied/moved, by PI units in the x direction and also PI units in the y direction, checkerboard fashion.
PI (+/-), is the length of an unwrapped circle of diameter 1 unit.

I read that the Bonnet transformation, with theta = 90 degrees, turns a Scherk1 into a Scherk2 surface. (?How to script?:-)
(Also applies for catenoid/helicoid, and for D, gyroid, P surfaces...)

- Brian
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  TOM (SIRTOM)
6524.20 In reply to 6524.18 
>>I've no idea if it can be modified to make nurbs<<
Very interested in hearing more about
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  TOM (SIRTOM)
6524.21 
Mike;

>>I got an .obj file from MathMod and then made it solid in MeshMixer.<<>>One possibility would be to use retopology tools in 3D Coat or something like Topogun to get a quad polygon layout and then use Max's sub-d to NURBS script to convert that to NURBS.<<

is it opssible in Meshmixer to go form triangle to quads `liKe Michale suggested ?
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  TOM (SIRTOM)
6524.22 In reply to 6524.20 
I have constructed a Sherk tower manually but the blends are not really smooth.

Is there a way to expand the Scherkscript so it will stack up saddles to build a tower ?
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  bemfarmer
6524.23 In reply to 6524.22 
This is the base unit, for Scherk2 tower, resulting from previously described lineweb, blends, trims, etc.
Just Stack and rotate appropriately.
The complete minimal surface goes to infinity at the poles, I think, precluding a simple "complete" script.
- Brian

The 7Z file is about 1/3 the size of the .zip file. The 7zip unzipper is a free program.
Attachments:

  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  TOM (SIRTOM)
6524.24 In reply to 6524.23 
Oh very helpful Brian, thank you very much !
Are you familiar with 3D FX graph ? Is it possible to
get it working with the fomula of a Scherk tower ?




Attachments:

  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  bemfarmer
6524.25 In reply to 6524.24 
Hi Tom,

Let u = r, the radius, which ranges from 0 through 1.
Let v = theta, the angle, ranging from just over 0, to (just under) 2PI ~= 6.2831253.
I tried the script equations with ln, sin, cos, and atan, which mostly reproduced the surface, with some problems with poles v = 0 and v = 2PI.

Using your implicit equation with sin, sinh(x) and sinh(y),
it becomes tedious to enter the equations into the fxgraph3d lines, so I've run out of time...
Best to write the equations in notepad++, as a .js file, and copy them over...then the parenthesis at least can match.
I set u = r and v = theta, as above, which I am not sure is right, but...
set x = u*sin(v)
set y = u*cos(v)

note that sinh(x) = (exp(x) - exp(-x))/2

z = asin((exp(u*sin(v))- exp((-1)*u*sin(v)))/2 * (exp(u*cos(v)) - exp((-1)*u*cos(v)))/2)
Does not work :-(

- Brian

EDITED: 20 Jul 2017 by BEMFARMER

  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  TOM (SIRTOM)
6524.26 In reply to 6524.25 
Thnak you Brian, as I see it is not easy I will see if I succeed !
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  bemfarmer
6524.27 In reply to 6524.26 
For the Scherk2 surface, the equation of a hyperbola in quadrant 1, with vertex at radius of 1 unit, is x*y = 1.
Points (x,y) which produce a z value are contained within the 4 hyperbolic curves.
(In contrast, the Scherk1 surface has a rectangular x,y source, so it was easier to program.)

I think that FXGraph3D could use a numpoints input(?)

EDITED: 20 Jul 2017 by BEMFARMER

  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  TOM (SIRTOM)
6524.28 In reply to 6524.27 
For a mathematician layman what you say is a bit like a Mandarin dialect ;-)
But I am trying to decipher your explanation !
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  bemfarmer
6524.29 In reply to 6524.28 
https://en.wikipedia.org/wiki/Hyperbolic_function

For a hyperbola, angle theta is not used, instead u is used, and is an area.
(For a circle, angle = 2*Area, so either can be used.)

- Brian

http://www.clayton.k12.mo.us/cms/lib/MO01000419/Centricity/Domain/241/ArticleHandout.pdf

EDITED: 20 Jul 2017 by BEMFARMER

  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  bemfarmer
6524.30 
The implicit equation did not work out very well, due to "poles," but here is the classic Weierstrass parameterization, as per Wikipedia.
The surface which results is the same as for the _Scherk2 long .js, .htm script, but lacks symmetry at two ends,
at least partly due to the lack of numpoints parameter in _FXGraph3d (?). So I prefer the long script, after processing, for the Scherk tower approximation.
The FXGraph3d version comes in two halves, due to the exclusion of zero, and replacement with .0001.
The .8 can be increased in value, if U and V count are increased.
The two halves can be networked and joined, offset, edge swept, and joined to a solid, for a super "pringle". A few Fillet tries did not work.

Scherk2WFirstHalf01
_FxGraph3D log((1+u*u+2*u*cos(v)) / (1+u*u-2*u*cos(v))); log((1+u*u-2*u*sin(v)) / (1+u*u+2*u*sin(v))); 2*atan((2*u*u*sin(2*v)) / (u*u*u*u - 1));0;0.8;0.0001;3.141592653589793;21;21;1;;;UV

Scherk2WSecondHalf01
_FxGraph3D log((1+u*u+2*u*cos(v)) / (1+u*u-2*u*cos(v))); log((1+u*u-2*u*sin(v)) / (1+u*u+2*u*sin(v))); 2*atan((2*u*u*sin(2*v)) / (u*u*u*u - 1));0;0.8;0.0001;-3.141592653589793;21;21;1;;;UV

- Brian

EDITED: 24 Jul 2017 by BEMFARMER

  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  TOM (SIRTOM)
6524.31 In reply to 6524.30 
Unbelieeeeeeeeeeeevable !!

How did you manage to out this formula together ... hats off
and thank you very much, Brian !!
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  mkdm
6524.32 In reply to 6524.30 
Thanks a lot Brian!

Very handy formula!!

Mathematics, this almost unknown "savage beast"...for me! (sigh)




Bye!

- Marco (mkdm)
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  bemfarmer
6524.33 In reply to 6524.31 
Thank's Tom and Marco.
The equations, as shown in Wikipedia, https://en.wikipedia.org/wiki/Scherk_surface, are the same as in the Scherk2 script.

The equations are the comprehensible result of some mathematician managing to integrate the nearly
incomprehensible Weierstrass–Enneper parameterization.
https://en.wikipedia.org/wiki/Weierstrass%E2%80%93Enneper_parameterization

For some other minimal surfaces, like Costa and Gyroid (I think), the integration must be done numerically, programmed with some
program like Mathematica. The programs create a triangle mesh, not NURBS.

- Brian

This Half version looks better, and uses zero. It can be Networked.

Scherk2WWalfToRotate01
_FxGraph3D log((1+u*u+2*u*cos(v)) / (1+u*u-2*u*cos(v))); log((1+u*u-2*u*sin(v)) / (1+u*u+2*u*sin(v))); 2*atan((2*u*u*sin(2*v)) / (u*u*u*u - 1));0;0.8;0;3.141592653589793;24;48;1;;;UV

EDITED: 24 Jul 2017 by BEMFARMER

  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
 From:  TOM (SIRTOM)
6524.34 In reply to 6524.33 
"nearly incomprehensible Weierstrass–Enneper parameterization"

From my perspective, what you have posted already looks pretty sophitiscated ;-)

Downloaded the last version- Thank you very much !!
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged
 

Reply to All Reply to All

 

 
 
Show messages:  1-17  18-34