How to generate a triangular line grid based on a collection of points?

Hi everyone,

I am fairly new to Grasshopper, but I've managed to construct a definition which will subdivide a triangular face of an Icosahedron, with the ultimate goal of building a geodesic dome with varying frequency (subdivision). I've come to the point where I can create a collection of 3D-points, lying on a sphere. These points are the endpoints of line segments, and form a triangular grid. (see attached file)

Now the problem: is there a method, or a VB-script which will connect these points in such a way that a triangular line grid emerges?

Any help or suggestions are welcome!
thanks,

Niels

Attachments:

geodesic_new2.ghx, 437 KB

Replies to This Discussion

Permalink Reply by Danny Boyes on October 18, 2009 at 8:47am

Have you looked into the Delaunay Mesh component or the Delaunay Edges found on the MESH tab in Triangulation.

Permalink Reply by Jon Mirtschin on October 18, 2009 at 10:29am

I could be wrong (I didn't try this), but I don't believe Delaunay would wrap the underside of your dome (assuming you're subdividing an entire dome). 2d Delaunay basically operates on a projected plane.

If a non-grasshopper solution is acceptable, I added code for various geodesic domes into my Structural Drawing Plug-in, http://ssi.wikidot.com . If you need the curves in Grasshopper, they can be assigned to a curve group and scaled/translated as needed. If it's useful but not doing exactly what you need, let me know and I'd try to address it.

Cheers,

Jon http://www.youtube.com/watch?v=bfrljz-l8b0

Permalink Reply by Niels De Temmerman on October 18, 2009 at 3:09pm

Hey Jon,

thanks for the tip. It is nice that you have added quite an extensive functionality for geodesic domes. Did you ever build one? I am researching deployable structures and have a student who will build and analyze deployable domes (cfr. Chuck Hoberman). I would be easier for me to have it all within grasshopper, because I need to add a lot of operations in order to turn an geodesic grid in a double layer scissor stucture.

You are right in saying that Delauney doesn't work for full domes, but there is a repetition in a full dome. there is great symmetry so there are only a few different elements, especially if you use a low frequency.

I tried to use SSI but couldn't get the trial version request command to work. mail wouldn't send.

A suggestion: would you deem it possible that you would create a grasshopper definition for your gesodesic domes, so everyone could use them, or would that be counterproductive...Because now there isn't a good working grasshopper definition that does what I saw SSI does on youtube. just my thoughts.

keep up the good work!

Permalink Reply by Niels De Temmerman on October 18, 2009 at 9:01am

Hi Danny,

Yes I tried that but Grasshopper crashes or hangs when I try that. Could that have anything to do with the fact that there is a strange 'null' value in my point collection? maybe the Null causes the hanging of grasshopper...

Permalink Reply by Danny Boyes on October 18, 2009 at 9:12am

Not sure. The data needs to be flattened in-order for it to be drawn correctly so maybe the lack of enough points in 4 of your 6 branches is causing the melt down. The image above was created by simply adding your E outputs to a flattened delaunay mesh component. Is the image what you expected?

Permalink Reply by Niels De Temmerman on October 18, 2009 at 9:19am

This exactly what I expected. I have tried it before, but it didn't work. But, as you said, flattening is the answer. I flattened it before I connected it and it no longer hangs and it is what I wanted.

Thank you very much!

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