When comes the UnrollSrf ?!?!?!?!

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Permalink Reply by oliver von Malm on September 16, 2009 at 2:11pm

No idea but I just wrote one to unroll planar surfaces using "orient srf". that works very well.

greetings, oli

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Permalink Reply by Jesse Pietilä on September 17, 2009 at 2:53am

Ok Oliver !

not to confuse any of us but I think that planar srf does not need to be unrolled...

do You mean developable instead of planar....?

please explain a bit more ; )


Let me see the link or so !


gretings jesse

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Permalink Reply by oliver von Malm on September 17, 2009 at 7:34am

Hi Jesse,

No, I was talking about planar surfaces or polygonal polysurfaces. This is just very useful if you have for example 100 polygonal objects i.e. houses and you want the facade and roof surfaces to arrange on a 2d sheet for lasercutting or cnc milling.

on the left side you see what it does. I marked the containers you need to, lets call it move and rotate, those surfaces to the c-plane.

Attachments:

• unroll_planar_srf.png, 405 KB

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Permalink Reply by Marc Hoppermann on September 18, 2009 at 2:56am

Hey Jesse,
As far as I know there is no unroll component yet.
You will have to utilize the Rhino command for it using app.runScript()
I've attached a ghx file that does just that.
As an input it takes the IDs of the surfaces. The output are the unrolled Surfaces which you can then number and distribute using grasshopper components.

Marc

www.21cd.org

Attachments:

• VB_UnrollSrf.ghx, 152 KB

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Permalink Reply by Marc Hoppermann on September 25, 2009 at 7:17am

Hey Jesse...

did it actually work out for you with the definition I uploaded? Just curious as I have only tested it on one pretty simple case so far..
Marc

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Permalink Reply by Jesse Pietilä on September 25, 2009 at 7:53am

Hey Marc,


I will test it soon ! ...


Best,

Jesse

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Permalink Reply by Arthur Mani on July 10, 2011 at 9:17am

Thanks Marc,

 

To get the ID of a BREP generated on GH do you need to bake it first?

 

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Permalink Reply by Mårten Nettelbladt on September 25, 2009 at 3:23pm

Hi Marc.
Thanks for sharing your unroll-script.
I'm trying it, but there is an error:

Can you see what I'm doing wrong?

Also, is it possible to have (unbaked) Grasshopper geometry as input surfaces?

Thanks
M&rten

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Permalink Reply by leon on August 13, 2010 at 3:24am

Hi Marc,

I know this is an old thread but i'm really keen to use your vb component to unroll surfaces using a line or point as a method of relocating the developed and curved geometries together again - as it is possible to do in the rhino command.

I have tried adding this into your component with no success and would assume it involves collecting the the input curves on the surface and selecting them as oncurve objects and assigning them as strings following the selection of the surfaces. Is it possible or am I way off target?

many thanks

Leon

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Permalink Reply by Shawn Fernandez on August 13, 2010 at 12:35pm

We were discussing unrolling curved surfaces HERE


Try the definition at this ... LINK Just be sure that your input is actually a developable surface. You can tell by cranking up the number of segments and watching the accuracy difference. If it's over 1% then your surface probably isn't developable to start with.

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Permalink Reply by leon on August 16, 2010 at 3:03am

Hi Shawn,

Thanks for your reply.

I have seen this link before and found it interesting. Strangely enough I studied with Urban Future Organisation and although this method is interesting it still has the same problem.

What I am particularly interested in is Marc's system of using a vb script to call in the rhino command which has a more stable and accurate output. The only drawback with this is the inability to reference a point or curve to align the developed and curved surfaces together.

Ultimately I want to modify Marc's vb script to utilise the full rhino command including the 'select curves on surface to unroll' part which would solve my issue. If I can do this then the entire process (of which this is a small part) can be completed in grasshopper without the need to switch out to rhino. The problem is not the unrolling it is locating the 2 geometries around a common point.

Thanks
Leon

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Permalink Reply by Shawn Fernandez on August 16, 2010 at 8:34am

The problem with the accuracy in the link I gave is based on two things. First is that the surfaces being unrolled are often NOT developable to begin with, (without meaning offense, the authors of the link I gave did not appear to know the difference between developable and ruled surfaces) and the second is the number of elements used in the approximation.

Do you happen to know if the rhino command is a mathematical transformation mapping the equations of the surfaces to 2-Space? If so then it wouldn't be an approximation at all, but an exact derived transform, something that I have been seeking after for a bit as well.

I think the unroll script was not intended to produce developable surfaces that crease or fold over as if generated from a single developable sheet, but rather allow for the creation of segmented forms that could not be created from a single sheet, but where each face was a separately developable surface that would be stitched together. While that does give some added functionality to the command to create shapes that otherwise could not be made, it doesn't really help those of us desiring to use a single developable surface.

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