Twisted multiple extrude

[RussU]

Hi all,

 

I'm scratching my head on this one... Two simple polylines to multiple extrude.

 

I want to go from bottom one to top one, smoothly. So Multiple extrude is the way forward.

 

So I put them on the same plane and execute the command. I get a twist.

 

The vertex count is the same in both profiles, and the direction of draw is the same, but it does seem like that the "start" vertext is in a differenct place. In other packages you'd choose the vertext and then "make first" on both profiles, to get the right ones to line up. But I can't work out how to in VW.

 

Have tried a convert to nurbs and do a no-rail loft, and I get the same result.

Any clues please?

 

 

 

Edited February 28, 2019 by RussU

[cberg]

Why wouldn't you convert to NURBS and loft the curves?

 

 

[RussU]

10 minutes ago, RussU said:

Have tried a convert to nurbs and do a no-rail loft, and I get the same result.

Thanks @cberg but I tried that, and it gave me the same result....

 

[cberg]

when you loft the curves do you generally select from the same area? 

[RussU]

Have made thesame in a subdivision surface, but still curious about the multiple extrude problem...

[RussU]

1 minute ago, cberg said:

when you loft the curves do you generally select from the same area? 

Yes, I do... so I get the red preview line going between corresponding vertices so I'm not getting expected results

 

 

[markdd]

Hi Russ

 

Loft tool should work. Its just about the alignment of the points

 

[Snacks]

I can't help but notice that no one ever answered this question. Is this just something you can't do in Vectorworks?

I'm trying to do something similar with two polylines that look like arcs (2 semicircular arcs made into a polyline), and I have redrawn them multiple times, beginning with the same point on both shapes, and nothing I do will make the multiple extrude command work.

So, my question is the same as OP: Is there a way to select "start vertex", or to align poly lines with identical numbers of vertices such that they don't become twisted messes, when multiple extrude is performed?

 

Thank you!

 

Casey

[VIRTUALENVIRONS]

@markdd  Answered this question.  But, post the file.  Someone will answer.  I can look at it tomorrow.

 

 

[Snacks]

Hi @VIRTUALENVIRONS,

Thanks for offering to take a look. I've attached the file, here.

 

You're mistaken. No one ever answered this question on this thread. I'll reiterate the question, to allay any confusion. The question is this: How can I create a multiple extrusion that isn't a twisted mess using two polylines that have the same number of vertices? The sub-questions are, is there a way to align polylines so the vertices are correctly lined up in a multiple extrude? Is it not possible to perform this extrusion as a multiple extrusion in Vectorworks? Can I select a "start" vertex to make sure the top and bottom polylines are extruding to each other properly?

There are answers to none of these questions on this thread, though I will admit, I do not know if perhaps these questions have been answered elsewhere.

If I have made a mistake and just missed the answers, please let me know. I did read through the thread again, just now, after you told me my question had been answered, and I couldn't find an answer anywhere.

In the attached file I have four sets of shapes to look at. They are steps of the same attempted extrusion. Polyline pair, failed multiple extruded polylines, polyline pair converted to NURBS, and lofted surface from NURBS curves. The multiple extrusion is a twisted mess. Obviously a loft surface from NURBS curves is a terrible way to create a multiple extrusion, because it has no geometric edit capability, but as far as I can tell, this is the only solution provided in response to the original question. Since it is not an answer to the original question, the question remains.

 

Thanks for any wisdom you may have to share about how to get multiple extrude to work properly.

 

Casey

Multiple Extrude Failure.vwx

[VIRTUALENVIRONS]

HI @Snacks  Interesting handle.    You are correct, I am mistaken, this answer remains un-explained......my apologies.

 

First of all though, I would like to try and dial in to what you're trying to accomplish.  Please view the short video below and tell me if this is what you want to do.

 

It is done with Multiple Extrude.  I only. extruded 5 units to keep it on screen

 

 

[VIRTUALENVIRONS]

Try the polylines in the enclosed file.  They are your curves.  I exported them back to 2024.  Let me know if they work and I will explain.

 

ME_1_FORUM_v2024.vwx

[Snacks]

@Virtualenirons, Thank you for digging into this. I had a boss once who gave me the nickname and for about seven years it stuck. Now there's basically no one who calls me that, but the handle was already there. 😃

What you're showing in the video is almost exactly what I'm trying to do. I am trying to multiple extrude 0.3cm, which is not quite as tall.

When I load your 2024 file and run Multiple Extrude, there is less distortion than before, but still some (image attached). Is there a step I'm missing to get this smooth? Why would 2024 polylines behave differently than 2025 ones?

 

Thanks for your time and effort in explaining this to me. I really appreciate it. 

 

Casey

[VIRTUALENVIRONS]

Hi Casey.  If I can give you a tip, try to avoid poly lines for 3D work.  

 

Multiple Extrude looks for planar objects that are the same....or come from the same object.  Your poly lines must have been derived from two different objects. 

 

What I did.  I took your outside poly line and scaled it down to match the smaller one....but that also reduced its thickness marginally.  Then I manually moved the two end points and middle point back to the original thickness.   So, Multiple Extrude saw two objects that were the same even though different.

 

Try this.  Use the reshape tool to physically move some points around and it will still Extrude.

 

If I am not clear, I can do a short tutorial.

 

 

 

 

 

[Snacks]

That makes sense. So, instead of drawing two separate polylines, I should draw one, then copy it, then scale it, then correct width. And if I do that, multiple extrude should work properly? Here's an image of what happens when I follow those instructions. It does work, if I just scale the copy and don't modify any of the vertices, so maybe that's the closest I can get. I'll poke around with these guidelines and see if I can get a clean extrude.

 

Thank you very much for taking the time to explain the pitfalls of multiple extruding more complex planar shapes. 

[VIRTUALENVIRONS]

More to come tomorrow.  Play with this a bit.

[Steve S.]

@Snacks

 

[Steve S.]

Using polyline, I drew the S shape once and then copied and pasted it.

Scaled one of the S's along the X

Using polyline, drew the straight line segments

Composed

Then did Multiple Extrude

 

Edited June 28 by Steve S.

[VIRTUALENVIRONS]

@Snacks  Multiple Extrude is highly under used.  Mostly because other tools have pushed it to the background.   In the early years of Vectorworks (MiniCad) I used this function extensively.  

 

As not to confuse this thread anymore, I am starting a new thread called "Multiple Extrude - "beyond the basics" I think you will find it interesting.

 

 

[bcd]

2 hours ago, VIRTUALENVIRONS said:

Multiple Extrude is highly under used

How can you proclaim this? Do you have access to VW tool tracking?

[VIRTUALENVIRONS]

Multiple Extrude (ME) can create 3D geometry that falls into its "wheel house" very quickly.  The cone below was made with a single ME application.

 

 

[Snacks]

@Steve S. I've never used Shell Solid before, but that's *exactly* what I was trying to do! I'm still amazed that after 22 years drawing in Vectorworks, I still have so many features I haven't learned about, yet.

 

Thank you, very much for the tutorial.

[VIRTUALENVIRONS]

HI Snacks.  I tend to answer questions based on the users specific needs.  As I stated earlier the Polyline tool is to be avoided at all cost if working in 3D, but that was the tool you were using, so answered based on that.

There are over 20 ways you could make this shape between standard tools, NURBS tools and Surface tools.  You could even make it with the terrain modeller.....I think.

 

But, there are differences between Shell and Multiple Extrude that come to play with architectural  elements.  The shell tool adds a thickness in a direction based on many factors, where ME is always perpendicular to the working plane. 

 

See below.

 

[Claes Lundstrom]

The problem with Multiple Extrude is that you lack control of where the starting points are located.

 

You can flip / reverse the direction of a polygon or curve. That's good. 

 

You can step through the individual control points and edit the location of it. That's also good.

 

What you CAN NOT do is to move the starting point. That's the problem.

 

Let's say that an extra option would be added in the Move popup, reading "Move Starting Point", and then do the editing with the arrows below. That would make Multiple Extrude way more usable and predictable. I have had it in my TouchCAD for years, and trust me, I use it a lot.

 

As it is now, the best way to avoid problems is to avoid using individually drawn objects. Instead make a copy of one of the parts and edit that to the new shape. In that way, you at least work with objects having the same basic DNA, and therefore avoid all sorts of problems.

 

 

[Snacks]

@VIRTUALENVIRONS, Thank you for your continued efforts in educating me. The number of times you have returned here with new pointers to share is amazing. I really appreciate your expertise, and the clarity you bring to the subject.

I understand that you were answering not only the question I asked, but doing so within the context I asked it. I had figured out a few ways to make the shape, but had been frustrated by the inability to further edit the underlying 2D shapes for a few of those methods. That's why I got stuck on multiple extrude. I knew if I could make multiple extrude work, then I could go into the solid and change the underlying geometry, if needed. Now, I know a few more ways to accomplish the same solid, and that feels great.

I learned a lot here, from you and others. I still have some frustration with the reality that @Claes Lundstrom describes so well above, but there are hundreds of things we all wish were a little different about Vectorworks. Most of them, we just learn how to compensate for them and then we eventually are less bothered, I think. This one just happened to be a real stumbling block for me on this project.

Again, thank you @VIRTUALENVIRONS, @Steve S., and even @RussU, @cberg, and @markdd for the tips and tricks I've learned from all of you here.

 

I'm grateful I can come here and there is always someone who knows more than I do who is generously willing to spend their time and effort to help me become a more effective modeler/draftsperson/CAD artist.

 

Casey

[VIRTUALENVIRONS]

@Snacks  Thank you for your kind words to all of us.   It is appreciated when someone takes the time to do this.  Makes my day anyway.

 

So, I have something for you or anyone else that wants it.  There is a file enclosed that are a set of matched planar curves/geometry.  No matter how much you distort these curves, they will always extrude to a "0" start point.  The short video below explains.

 

SQUARE TO CIRCLE_FORUM.vwx