Parametric Truss Problem

Grasshopper beginner here,

I recently followed this tutorial to achieve a parametric truss effect

http://designreform.net/2009/07/20/rhino-grasshopper-parametric-truss/

The only difference is my surface was not lofted, like in the tutorial, but belonged to a network of surfaces which once formed a solid. In other words, to create this surface, I 'exploded' the solid and additionally split the surface. The end result after trying to apply the parametric truss to the surface was unsuccessful because for some reason it follows the original surface, not the one that was split.

I've tried 'rebuilding' the surface with no luck
'MakeUniform' didn't work either and neither did a 'reparameterize'.

Is there a command in Rhino that separates the surface from its original 'placeholder' or whatever is keeping me from using the specific surface?

Similar to the tutorial, I'd like to create the parametric truss effect contained only by the surface.

Any help is appreciated
thanks in advance.

Replies to This Discussion

Permalink Reply by Shaun Delautour on July 27, 2009 at 1:42am

May have found the problem, The surface has 5 points instead of 4...
My question is 'How do I go about using a 5 point surface to create this pattern?'

Permalink Reply by Vicente Soler on July 27, 2009 at 9:39am

Your surface probably has a trim that hides the part of the original surface, but its still there. I think that the tutorial uses the subsurface component which ignores the trim, so it will panel the surface in its untrimmed form. The best you can do is recreate the surface to make it smaller. Try the commands "ShrinkTrimmedSrf". It's tricky (although possible) to make a 5 corner surface without involving a trim. If you post the file i could try to make it a single untrimmed surface.

Permalink Reply by Shaun Delautour on July 28, 2009 at 3:22am

The attached files are the 5 sided surface and parametric truss ghx. file.
Thanks for the interest

Attachments:

5 Sided Srf.3dm, 127 KB
Parametric Truss.ghx, 200 KB

Permalink Reply by Vicente Soler on July 28, 2009 at 11:08am

The problem with that surface is that one of its sides is much thinner than the other, since the subdivs are the same on all of the surface, the truesses become much smaller and denser in the thinner side, using an untrimmed surface. I think it would be better to keep a more rectangular shaped surface with an added trim and then filter out the trusses you dont want. Nevertheless, i attached the untrimmed surface, so try it out. Remember that surface subdivisons vary depending on how the nurbs surface was created. There can be different subdivision results for surfaces that geometrically appear to be the same.

Attachments:

5sidedsrf_notrim.3dm, 135 KB

Permalink Reply by Shaun Delautour on July 28, 2009 at 10:05pm

Thanks, that works quite well. However, how did you untrim the surface? I tried using ShrinkTrimmedSrf but that alone doesn't achieve much. Is there a way in Rhino to redefine the subdivisions? I'd like the surface to be divided horizontally if you know what I mean, in fact heres an example of what kind of effect I'm trying to achieve:

Attachments: