Parametric Truss Query

Hi all,

I'm trying to follow this tutorial online but the logic is breaking down when I try it. could anyone point out why this is for me as I cant figure it out.

It breaks down when I change the Expression of D in the Offset component to -d?

Hopefully this is an easy one to solve for you.

I have attached the relevent files from rhino and GH, here is the tutorial URL: http://designreform.net/2009/07/rhino-grasshopper-parametric-truss/

Cheers people,

Dave

Attachments:

Parametric Truss 1.3dm, 29 KB
Parametric Truss question.ghx, 126 KB

Replies to This Discussion

Permalink Reply by Danny Boyes on April 4, 2011 at 4:29am

Hi David,

The recent changes in RhinoCommon for Offset have caused a great deal of grief and I don't know what's being done or even what needs to do (I don't work for McNeel).

What I do know for sure is that the only reliable way to get the results you want from offset is to not use it (at the moment). Numerous work arounds have been suggested including offset on surface (processor hungry) of Offset both sides and then cull the unwanted object. This later one is of cause no use to you as the component is failing when you change direction (for this example).

I would suggest using a scaling component to offset the curve instead. You will need to calculate the distance required as a factor to scale by and you will also need a centroid of the polyline for the centre of scaling.

In order to keep the processing requirements lean I've used the Average component to get both the Centroid and A reference point to measure the offset distance against.

If you need to incorporate a direction for the offset then there is an optional Fx component that will change the factor for scaling instead of having it hard coded into the Scale Component. It does this through a boolean toggle on a Stream Filter Outside = True then the Function of the Fx component is 1+x; False then 1-x.

Permalink Reply by Danny Boyes on April 4, 2011 at 4:32am

forgot to add the GHX

Attachments:

ParametricTrussSolution.ghx, 201 KB

Permalink Reply by david b golding on April 5, 2011 at 5:57pm

Cheers Danny.

Would you have any idea why I cant open the GHX you sent? When I click on it, I am forwarded to what looks like a page of computer code? I have tried to drop and drag it into the GH main screen, but that has no outcome? do you have any problems like this? or know of any solutions?

Thanks again for your help, Ill get onto that now.

Permalink Reply by katieB on April 5, 2011 at 6:16pm

if you right click on the file, and download it and then open properties(pc)/get info(mac) and delete the extension .txt at the end. you can then open it in grasshopper, this happened to me earlier

Permalink Reply by Danny Boyes on April 6, 2011 at 2:14am

It's very hit or miss whether it downloads or goes to an XML page in your browser. If this happens I just Right click save as and then it starts to download. I've never had to go through the hoops that KatieB has suggested but there could always be a first.

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