Get sides of Cylinder Element

[Anonymous]

Does anyone have ideas on specifying a particular side of a cylinder/element (attached pdf). I need to get the northern/top side in this view.

I know this could be done manually by picking one side or the other on the element, however I am attempting to this with no user input.  

I have attempted using the actual geometry class in hope of being able to cycle through the faces but since it is a cylinder I am only getting mesh objects which I am not entirely sure how to use in this way. Any ideas are much appreciated.

[jeremytammik]

Depending on how the cylinder has been constructed, the two sides you point out may actually belong to the same face. Therefore, there are possibly no two faces there at all. So, you will have to specify more exactly what you actually want to achieve. If you need a point on the north side of the cylinder face, you can calculate it by projecting a point lying further north down onto the cylinder face, for instance.

[Anonymous]

Thanks Jeremy.

Unfortunately, I came to the same realization. Using a point that is just somewhere north of the pipe in the original pdf would work perfectly for that instance but it would not always be the case. I realize now I should have given some deeper context and thought out the question more thoroughly. To elaborate...

In general this is only needed in instances where the pipe is connecting into a elbow (as in the pdf). When it does so I need to get the side of the pipe that is on the corresponding longer radius side of the elbow it is connecting into. In case this is a little confusing I attached another pdf with misc examples. 

I suppose the real question I should have asked is how to get the longer radius side of a elbow fitting.

I have tried a few approaches thus far... first bounding boxes,  then connectors, and now geometry. But haven't yet yielded any consistent results due to the variably of the instances. Apologies for any confusion.

[jeremytammik · Accepted solution]

Thank you for the clarification.

Oh, but that is pretty easy, though.

Of course there are innumerable ways to approach and solve it.

Here is the first that comes to mind:

The elbow has two connectors, and they each have a connection point and a direction pointing out of the elbow, say, `p`, `q`, `v` and `w`. These two points and vectors define two infinite lines. The two lines intersect somewhere, let's say in `r`. The intersection point is the same as the intersection point of the two connected pipes location lines, extended to meet. The outside edges of the two pipes lie on the 'outside' of `r`, where the 'inside' of `r` is defined as the part of the plane spanned by all positive linear combinations of `v` and `w`.

Sorry I have not spent more effort on putting this more concisely, but maybe you get the idea.

If not, say so, and I'll draw a little sketch to clarify what I am blabbering about.

[jeremytammik · Accepted solution]

Here is the sketch, in case it helps:

Please excuse my poor digital drawing skills.

[Revitalizer]

Make better drawings by using Revit 😉

[jeremytammik]

I'm afraid I seem to be sort of allergic to that kind of thing.

Problem is, I seem to be allergic to GUIs in general...

Nice new avatar picture you chose! Found the right question yet?

[Revitalizer]

It's just my age.

Didn't find the answer yet.

By the way, "42" is just the rounded value.

In fact, the right value is "42.195" 🙂

http://www.marathon-kevelaer.de/index.php/en/informationen/faq/134-was-ist-der-sinn-des-lebens

Rudi

[jeremytammik]

I assumed 42 was the answer and the question yet to be determined...

https://en.wikipedia.org/wiki/Phrases_from_The_Hitchhiker%27s_Guide_to_the_Galaxy#Answer_to_the_Ulti...

[Revitalizer]

I read the books many years ago, so I don't remember the details any more...

Getting older...

😞

[Anonymous]

Once again thanks Jeremy!

I don't know how I overlooked the obvious. Tunnel vision I suppose. 

[jeremytammik]

Thank you for your appreciation.

My pleasure entirely.

Shared here for posterity by The Building Coder:

https://thebuildingcoder.typepad.com/blog/2019/09/extensible-storage-external-event-dll-and-pipe-fac...