How to create tetrahedron for any given angle in grasshopper?

Replies to This Discussion

Permalink Reply by David Rutten on January 16, 2011 at 12:50pm

You could try using a FacetDome. It limits the solution to a polyhedron that is constrained to a sphere, but it might be enough...

 

 

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David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by Daniel Piker on January 16, 2011 at 1:10pm

Here's a start that at least gives the right topology

 

I'm assuming this is related to this discussion 

http://www.grasshopper3d.com/forum/topics/how-to-create-nodesbone?c...

in which case I guess its mainly the topology you are after.

(it needs the lines to all start at your node - so you might need to flip some of them)

 

There's probably a better option than using the same curve parameter for all lines - some way of weighting them so that it stays centred on the node.

 

Another option would be to intersect all the normal planes

 

Attachments:

• tetrahedron_node.ghx, 185 KB

Permalink Reply by Wiktor Kidziak on January 16, 2011 at 2:45pm

Daniel, thank you very much for your reply!

Yes, it is related to my previous discussion :) 

 

Your definition is exactly what I am looking for, however I would like the direction of  the faces of the tetrahedron to be the same as the direction vectors of the curves around which it is created. Do you think that would be possible?

 

Attachments:

• direction_of_faces2.3dm, 113 KB

Permalink Reply by Daniel Piker on January 16, 2011 at 6:04pm

You could just boolean some boxes from the normal planes to the curves, but you'd end up with some fairly spiky tetrahedra when the angles were irregular.

It might be better to use the outer tetrahedron in the definition above, and truncate it with planes normal to the curves. Splitting along lines from edge midpts to the centre could then give you the quads you need for subdivision and relaxation.

Nodes with 3 legs should be easy, but nodes with 5 or more would be quite a bit trickier.

Permalink Reply by Wiktor Kidziak on January 17, 2011 at 2:21am

Thank you for your suggestions. I will try both methods and see which one works best for unrolling and casting with concrete. I will post my result soon :)

Permalink Reply by Wiktor Kidziak on January 16, 2011 at 4:03pm

Also can I use this logic for 3 and 5 legs?