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# Thread: Easy Parametric Polygons

1. ## Easy Parametric Polygons

Has anyone figured out how to make a 5,6,8 etc. sided polygon easily parametric? You would think since on creation it is defined by a radius that you could "keep it grouped" or something so you could use one parameter, but I have to make multiple ref planes to make it work.

any ideas?

2. Conceptual modeling tools: use a ref line circle and place points on the circle. Use the Measurement Type parameter for the point, set it to angle, and specifiy the appropriate angle for that point whether its a 5,6,8 etc sided poly. The connect the points 2 at a time using spline through points.

3. Tried it for a detail component, started with one polygon segment, constructed by a connenction between the intersection of circle reference line with parametric radius and refencre line from circle origin to circle with parametric angle. See image. As you said, didn't work.

I have more faith in constructing the segment from the hypothenusa, using the formula's by Munkholm for arc length. http://www.revitforum.org/tutorials-...day-usage.html

load into another family, link parameters and make a parametric circular array. Will probably work for model families as well, not so sure about profiles.

4. You guys are overthinking it... You just need a set of points which you can align and lock the lines to. See attached...

I attached a detail component family. Inside is a nested DC which is arrayed in a circular array 6 times. The nested component simply is a corner of two line pieces on the default refplane. I tried using the circular refline's center first, but that doesn't work (you can delete it). Made the lines not visible so they won't bother you in the parent family.

In the parent I drew some lines from endpoint to endpoint and constrained them. That's a bit of a hassle since you need to constrain the endpoint of the lines. Lot's of tabbing (hint: use shift+tab cause the option to constrain the endpoints is the third from the end) but it get's the job done nicely. And presto: it's done: the radius is now parametric.

As for the amount of corners in the polygonic form: that would probably be doable too, but I'm guessing you'll need some major trig and another level of nesting. When you make the child family's marker lines visible again you can see that these lines rotate too. So if you were to nest the child into a second family, and calculate angle and length of the line there (based off course on the radius) you would probably be able to construct the entire polygon based on a circular array of the second family... If you get my drift here.

If not: I feel a blog post coming on...

5. Simple is always clever (or should it be cleverer?)
Nicely done MdR.
(Not sure where it's broken but all the internal angles are not the same)

6. This is a parametric circumscribed polygon, of any radius and any number of sides. Well, from 3 sides to... how many can you specify until Revit complains?

7. Elegant Alf. Kudos

8. Originally Posted by Alfredo Medina
This is a parametric circumscribed polygon, of any radius and any number of sides. Well, from 3 sides to... how many can you specify until Revit complains?
nice ! very very nice !

9. nice. forgot that a polygon by defenition goes all the way round, AND that the radius for a cicular array can be labeled. oh well, we live and learn.
seems that to rotate the entire thing it needs to be nested again though.

10. Now why couldn't revit have just coded them to keep the value in the first place.

Beautiful work by the way.

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