The SE-FIT surface evolver is a free windows program which will also do the Brakke surface evolver .fe files.
It has several export formats. I used the obj (Nwave) export, which produces triangles (and/or quadrilaterals?), and then obj23dm.
I'm not sure which is the best export format, to finally get to some .3dm file. Network did not work with the
triangles. Maybe a polyline to curve step is needed? Export of the whole "cube" is also possible, but the default is a segment.

Very good explanations are here:

http://se-fit.com/downloads

http://www.youtube.com/watch?v=Y_wkVNm3jhU

http://www.youtube.com/watch?v=MUaNAILPztY

http://www.youtube.com/watch?v=8T0fTcfPwWM


In MoI, several mirrors were done with the segment, and one rotation, to get the "cube" Schwarz P surface, with NURBS triangles,
not nice NURBS curves.

(See "batwing" MoI discussion.)


Brian

Hi Brian,

if you are familiar with the original Surface Evolver, you just need to use the "showcube" command, to generate the whole surface. And then save it as .off file and convert in Meshlab etc. to .obj, to bring it in your rendering application. Takes less then 60 seconds. ;-)







Regards
Stefan

This form is not the same than a crossing union of 3 tubes +fillet intersection and keep only surface ?

Thank you Stefan. I need to do some more practice. I wanted to turn the patch into Nurbs curves approximation of the minimal surface.

Hi Pilou:
I do not remember all the details and exceptions of how energy, area, and minimal curvature are related.

Soap bubbles constrained by curved wires have minimal energy and minimal area, but may not be of minimal curvature.

The Schwarz P-surface is of "minimal curvature," with local mean curvature of zero.

A minimal surface may not have minimal area.

I hope that I got the above right :-) - Brian

Edit: I came across this statement:
"As long as the soap film doesn't actually enclose any air, it will try to minimize its area - so it will end up being a minimal surface"

I added edge polylines before mirroring.
One segment can be mirrored 3 times in top view, for 2 cubed = 8 segments.
Two more mirrors in right view yields 2 power 5 = 32 segments.
Rotation copy of two 8 segments yields 48 total segments.
A solid can be created.


One segment consists of two parts separated by a straight line. Doing this trim enables a half
catenoid-like surface, with one square end, to be created.

- Brian