How to select sketch objects within a computed outline

[mikLamming]

I want to extrude a set of outlines using an in-sketch outline.

I have reduced my challenge to the simplest example I could devise.

The <PolyCountN> polygonal outlines shown are generated by a circular pattern.  Subsequently, all bar one polygonal outlines are to be automatically selected for extrusion.  They are specified using the also computed pie-shaped outline (the construction outline in the sketch) .

The number of polygons is a parameter, in this case 5.  For simplicity the pie-shaped selection is computed from the <PolyCountN> parameter.

In this case I did the job by choosing the polygoes with the mouse.

If I change the the parameter<PolyCountN => 12> I want the selection to be recomputed using the new pie-shape, and a different set of polygons extruded, e.g. eleven polygons, like this.

Can this even be done without my writing code?

Mik

[jhackney1972 · Accepted solution]

If you use a parameter to pattern the sketch, you will always have to select the sketches create the bodies.  If you change you process and pattern the original body, you will get what you desire.  Video will show this.

[davebYYPCU · Accepted solution]

Sketch Patterns are not recommended.

You can get there with a changed workflow.

Extrude the first shape.

Circular Pattern the body as you wish, your parameter can drive the count.

To leave the hole in the pie shape, you drive the appropriate pattern angle.

Might help....

[mikLamming]

Thank you John and Dave,

Thanks.  It's all so obvious when you see it.  

[davebYYPCU]

Updated file for parameter driven pattern. (Will overwrite the previous one.)

[mikLamming]

John and Dave,

I notice your solution works well if the collection of polygons are to be "unioned" to the design. If they are to be "subtracted" from a parent object, then there doesn't seem a way to dynamically select them.

I tried making selection sets using "Select by boundary" and so forth, but then the selection set feeding the "Combine bodies" command can't be programatically updated, or fed into the combine command

Is there another workflow fix this old geezer is missing?

Try changing the <PolyCountN> parameter to a higher number to see the issue.

Mik

[davebYYPCU]

Common problem, again another workflow thing, you sound like you will understand this as well.

Edit: Wasn't sure why you are using Combine, but realised after posting, 

Check out the second file.

Might help......

[mikLamming · Accepted solution]

Gentlemen, thank you for indulging me.  I have just been introduced to a word that somehow I had managed to avoid understanding - "feature".  How in a lifetime of using computers did I manage to snatch ignorance from the jaws of knowledge?

I'm not quite sure how to define the concept: feature. I'll come to it in a moment, after explaining the solution to my dumb question.

So my understanding is this:

If you want to create the usual pattern of bodies then the familiar and simple dialog goes like this.

And of course, you get this:

If you want to make a pattern of holes, then you select Features instead of Bodies and attempt to indicate the hole shape to be patterned by pointing to one of it's faces... comme ça.

and you get this:

YAY!

But here's my particular major learning event.  I think I discovered what a feature is - something I should have learned a year ago.  It is: the effect of exactly one icon on the timeline.  (How did I manage not to associate this word for that concept?  - I must be a genius. )

So it turns out that in both of the above cases I can select the "Features" mode and simply select the icon of an earlier feature in the timeline with which I want to pattern.   Amusingly enough a little advisory text pops up to tell me this gem of knowledge, but again, I managed to esacpe seeing it.

So now I have some intuition what a feature is, as well as how to pattern holes. 

I did try to find the definition of "feature" to see if there was more to be learned, but so far it's either too obvious, or too subtle 🤔

[davebYYPCU · Accepted solution]

Be careful - you do have a pattern option to select "Faces" as an option, (in the window on the model)

So, stick to selecting Features off the Timeline.

Can't believe you didn't know - Edit Feature - in another context.

[mikLamming]

Dave, Thanks for your herlp and the warning is noted.