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

[Steve S.]

First quote below is from another discussion about Multi Extrude

 

On 6/28/2025 at 9:00 AM, cberg said:

VW needs to review all these "quasi-legacy" tools and modernize them.  It feels like they were developed in the 1990s and haven't been thought about again since then.

 

12 hours ago, Snacks said:

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.

 

I’m not sure what the best use for something like Multiple Extrude is.

 

Long term CAD use has led me to conclude that I am not going to cajole a large company to make a product in the manner I would MOST LIKE. I may get them to change a thing here or there, but, Vectorworks is what it is, and that is why I use it - for its architectural tools.

 

And along these lines  — VW is not a ONE & ONLY product for me.

 

Numerous VW CAD folk use rendering products outside of VW. And seems I’ve read how some use Rhino from time to time. Maybe some use Blender. I use an outside product that works well for me in modeling 3D parts

 

So I use VW’s architectural tool set. But when it comes to parts, I will likely use another CAD modeler that is faster with a toolset easier to recall - at least for me.

 

[Steve S.]

On 2/28/2019 at 6:20 AM, RussU said:

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.

 

Any clues please?

 

Though they are on the same plane, they appear to be to the side of one another.

IF THIS IS SO, then try not only having them on the same plane, but also directly over one another instead of side by side, before implementing the Multiple Extrude command.

 

 

[Steve S.]

3 hours ago, Steve S. said:

Long term CAD use has led me to conclude that I am not going to cajole a large company to make a product in the manner I would MOST LIKE.

 

MAYBE BETTER SAID --

Long term CAD use has led me to conclude that I am not going to cajole a large company to GREATLY ALTER THEIR EXISTING PRODUCT INTO SOMETHING  REFLECTING ALL MY CAD NEEDS OR WANTS

 

Edited July 5 by Steve S.

[Pat Stanford]

On 7/4/2025 at 12:59 AM, Claes Lundstrom said:

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

I just tried something and it seems to work. Can you and/or @VIRTUALENVIRONS comment on this?

 

I took a polyline with straight and curved segments and Decomposed it to individual segments. I then Selected 2 segments starting with where I wanted to the "new" first point to be and Composed them. I then selected all of the other segments and Composed them with the 2 segments.

 

When I select the Move: Vertex Only mode in the OIP and click on the circle for the vertex, it chooses the vertex of the 2-segment piece farthest from the composed section. So it appears to me that that sets the first vertex.

 

A pain, especially if you have an object with many segments, but possibly a way to accomplish the needed task.

 

Multiple extrude of 2 pentagons. Top is scaled 50% to the bottom. Left has the top pentagon rotated by 144° (2 edge twist). Right is duplicates of the left, but with the decompose/recompose trick run on the top pentagon.

 

 

[VIRTUALENVIRONS]

One of the things confusing this issue is the comparison to NURBS and the starting point.  I "think" this plays a part, but only a part.  Multiple extrude is looking for objects that it sees as the same.  In my example above of the four curves being used to create two extrudable objects, Multiple Extrude saw them as the same.  If I used one of Snacks curves and mine, the Kludge effect would come into play.

 

@Pat Stanford  Very innovative thinking, but I think you managed to create an object that Vectorworks saw as "the same".  I recreated your method and it worked with a pentagon, but not with the objects in the video below.  Perhaps I am missing something.

 

"Just sayin'", if we could only get this traction going on NURBS modelling, the user base would be much farther ahead.

 

 

 

[line-weight]

On 2/28/2019 at 2:20 PM, RussU said:

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

 

The loft tool gives you a preview of the starting vertex, and the ability to adjust it so as to match vertexes between the two polygons as you wish.

 

 

However...this reminds me of a limitation of the loft tool, which is that even if you choose "ruled" it doesn't create a solid that is made of of triangulated flat faces - you get something like this:

 

And you can see it creates four-sided faces which are not flat.

 

Quite often I don't want that - I want flat faces. I've never really used the multiple extrude tool before. Looks like it can nearly do what I'd want but unfortunately doesn't let you match starting vertices in the same way that the loft tool does.