problem with creating a single surface from multiple surfaces - URGENT

Hi,

I have a feeling the solution to this question may be simple but for some reason i cannot seem to get it to work on my own. my problem has been mostly that i cannot figure out which component to use/ and when i do try with a component using multiple curves it seems to get an error which I do not understand - which is why i have attached the ghx and rhino files for you to take a look at as well as a pdf diagram to hopefully explain the situation better.

ok, so i have multiple individual lofted surfaces which overlap. i would like to find a way to create a single surface that only contains the external faces of all of these lofts (ie no overlapping - the interior would be hollow (or solid fill if its a brep....? i think - sorry terminology not my strong point).

although i have modelled these in my definition as breps i am not really concerned with the surface type - i have no real idea what the difference between surfaces, breps and meshes are and ultimately i plan on exporting a single surface as an OBJ file. what i mean is - do whatever you have to do to create the surface.

the pdf show images of what i am trying to achieve.

i have one request - if someone does figure this out please please post an image of the definition with the names of the components (or better yet the ghx file) not just the symbols since it is quite difficult for me to figure out what is going on.

thank you so much for taking a look

Ken

Attachments:

send off.pdf, 1.5 MB
the_scenario model.3dm, 75 KB
Iteration_1_with_circle_gotten_rid_of.ghx, 2.1 MB

Replies to This Discussion

Permalink Reply by Fred Becquelin on February 17, 2013 at 9:44am

Terminology is crucial when talking to a computer. I think this is why your definition is so complicated.

1 The error in the red "TOP OF DOMAIN SURFACE" component, as it shows when you hover the mouse over the bubble, is that you try to input a Point to a Surface variable. No can do. The point comes from the scale component above where you plugged a surface and a point. But this error is harmless actually, although it costs a few milliseconds to handle it.

2 There is n such thing as a "solid fill" in rhino. A brep is mostly a polysurface. It may be closed. If it is closed then you can make boolean operations with it (solid union, difference, intersection)

So first you need to close each cone, which you apparently tried to do. The best way of doing so

I think is to create a capped closed loft in one go with polylines, and not two lofts of lines + a planar circle. The circle wouldn't join the lofted cone anyway, lofts don't make circles. (Oh yes, a circle is a subcategory of nurbs curve, they have weights on control points)

Since you want meshes in the end I'd mesh these closed polysurfaces (ie closed breps) before making the union (mesh union this time) since operations on meshes are usually faster and safer. Plus you can use weaverbird to smooth or thicken it easily if you want.

see attached.

Attachments:

Untitled.3dm, 69 KB
unnamed.gh, 7 KB

Permalink Reply by Hannes Löschke on February 17, 2013 at 9:58am

Once again a case of "How would you model it in Rhino". You probably know the answer: create solids for each cone and boolean union all cones. Well, that's exactly how it works in GH.

You got one problem with this: the way you create your surfaces doesn't allow rhino to join the top to cones 1 and 7 within the current tolerance. That's not a GH or Rhino problem, it's "bad" geometry, you created. Anyway... here's a quick sketch of how the union would work, if the cones and top could join.

Attachments:

Iteration_1_with_circle_gotten_rid_of_solid_Union.ghx, 2.2 MB

Permalink Reply by Kenneth Allan on February 18, 2013 at 4:37am

WOW i have just taken a look at what you you sent back - really goodd work - much better logic in the model than what I was trying to achieve.

thanks a lot guys!

Ken

Permalink Reply by Kenneth Allan on February 20, 2013 at 9:30am

hey guys after looking at the thing again I still have the problem that i cannot select the external surface only but instead i have a mesh of the whole thing. i effectively need the surface only and it be hollow on the inside. i cant see to figure out how to do this.

Permalink Reply by Hannes Löschke on February 20, 2013 at 9:45am

You could test mesh faces for proximity to top and bottom surfaces and cull those that are coincident (within a tolerance). Or since your top and bottom are close to flat, you could use the angle between face normals and Z to separate roof and facade.

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