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Fairfax

Creating shelves from a lofted surface

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Hello,

I am trying to create a series of shelves, or "ribs" where the front profile is defined by a lofted surface. i.e., the profile of the shelves will vary by elevation, and their profile will be defined by this lofted surface. I want to do this in Marionette, but, to start, how does one do this manually?

I've created a sample file with two versions, one with the profile curve as a generic solid, one as a NURBS curve. The shelf section is 1" thick, a NURBS curve in both cases. It seems like the "Project" tool in "Add" mode should do what I want, but I can't get anything to work. I've also tried this with two solids in Add, Subtract, Intersect, etc. Any help would be appreciated!

Thanks,

Graham

Here's an image of what happens with "Intersect Solids" which leaves me with the front edge of the shelf, before and after "Intersect." While this is the correct front profile, I need the rest of the shelf behind it.

Thanks,

Graham

Edited by Fairfax

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Not sure of geometry here, but I am imagining shelves in a boat where front and back of shelf is concentric with shape of hull. So, assuming that is somewhat correct, take a look at Model>Intersect Solids. The loft is the cutting surface.

Post back with images or more detail.

-B

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I tried that, but it doesn't work since it just gives me a sliver of the front profile of the rib, not the entire rib. Here's the type of operation I would like to perform, with the half sphere replaced by the lofted surface in the VW file I uploaded in the original post: http://app-help.vectorworks.net/2016/eng/index.htm#t=VW2016_Guide%2FShapes2%2FCreating_a_Rib.htm%23XREF_76751_Creating_a_Rib

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The Project tool is not behaving as described in Help. The rib creation only works for me if the shelf profile is smaller than the surface. It is not able to trim a profile (as indicated in Help)that extends beyond the projection of the surface. Not sure why.

So, in Right view, reduce the length of the shelf "rectangle" at both ends so that it lies entirely inside the extents of the NURBS surface. Trimming surfaces to cut the profile at each shelf height could be created from the left and right edges of the NURBS surface.

I will try to post a screen shot later. Other duties call.

-B

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Thanks for that! I got it working as you did. Unfortunately, I don't think it works in Marionette at all. Any thoughts? Any thoughts on another method to achieve the same effect?

Thanks,

Graham

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I'm mostly uneducated in Marionette. But others here may be able to fill in. I'm thinking that Marionette for this is a super exploration, but for a one-off might take more time than just trimming and projecting. If there is need to examine 100s of shelf locations and different cutting surfaces then the Marionette would be a huge time saver.

Also, the Project tool refusal to trim during rib creation may be a bug. At least it should work as described in Help.

-B

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I am having to iterate various designs of the shelves. This, plus curiosity, is why Marionette is in the picture. I just heard back from a VW Marionette expert (thanks Sarah!) to try the "Contour" function, which also has a node in Marionette. This is a bit cumbersome because it creates NURBS curves which then need to be converted to polygons to "trim surface" the shelf polygons, which are then extruded, unless there's a more streamlined approach. Thanks!

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Hi,

Not sure if this is what you are after. I have used the 3d contour to slice your 3d object up then converted each splice to a 2d poly then extruded them.

The process is relatively quick.

HTH

Edited by Alan Woodwell

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Contours tool could work unless vision requires the "back" shelf face to be coincident with the NURBS. Then more work would be needed for each shelf.

Two consecutive contours, spaced at shelf thickness would define the back face of the shelf, tilting and twisting for continuous contact with the cutting surface. These contours would need to be spaced at shelf thickness. Then the front face of the shelf could be formed with 2 straight NURBS curves. Then loft the 4 curves as a ruled solid. Recontour required for each shelf to get the shelf spacing.

I had that same disappearing section of the NURBS surface during Stitch and Trim. Not sure why. The surface stayed intact if I selected the 21 NURBS surfaces >Add Solid (successful!), then Convert to Generic Solid for future operations.

Anyway, here is my take on trying to make ribs with the Project Tool. Still can't figure out why the NURBS curves representing front face of shelf is not trimmed by the Project Tool.

-B

ubbthreads.php?ubb=download&Number=14886&filename=Ribs.png

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Alan,

Great! Could you explain this in more detail? i.e. You take the NURBS curve and do contours with a horizontal line as the guide? I need to do this because I need the shelves evenly spaced and that even spacing is not an integer multiple of the shelf thickness.

Assuming this is the correct approach, I end up with NURBS curves that are just the front profile of the shelves. How do I extrude them into what you have shown?

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Benson,

Thanks for this. I think I'm understanding your process. I don't know that this is a wrinkle, but the shelf spacing needs to be uniform (i.e. the height of the solid divided by rounded-down integer value of the height of the solid divided by a minimum shelf spacing.) The shelf spacing is not an even multiple of this value. My understanding of the contour tool is that it only takes one delta value.

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Benson,

I get where you're coming from, thank you! It is actually the front of the shelves that twist and turn. I'm an architect seeking to make things complicated! ;-)

Speaking of complication, it seems like this operation would be rather time-consuming, since I need to create 8 shelves in each design iteration, and anticipate it will take numerous iterations to make this thing look "right." This was my original impetus to use Marionette, which automates operations, but adds a whole other layer of complexity and uncertainty to this effort. Note to self - "Be careful what you wish for, 'lest you get it!"

As I feared, once the most obvious approach (projecting) fails to work, the workarounds are much more challenging.

I'll keep at this!

Regards,

Graham

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Hi,

Refer to my short video so you can understand how to do it.

HTH

Edited by Alan Woodwell

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In case the rib creation is still in play, I got it to work. The trim component shown in Help only works if the curve to project is enclosed by the target surface (not a great limitation).

Start with a duplcate of the original surface for this one. Select the dupe original surface and those two guide object "wings" from pervious post, then Modify>Add Solids. The Project Tool doesn't project to a Solid Addition (why not?), so Modify>Convert> Convert to Generic Solid.

Project Tool, Add mode creates the shelves/ribs and trims to the wings.

-B

ubbthreads.php?ubb=download&Number=14893&filename=Ribs%202.png

Edited by Benson Shaw

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Benson, Hi you always have such good and well described solutions, You should create short videos which conveys the process easier.

If you have powerpoint on your computer click insert and video and you have the choice to create a screen recording with options to select screen area, record voice and mouse.

Look forward to seeing some.

Regards

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I see compliments about my posts lately. Many thanks for the confidence and the kind words! This forum is full of amazing talent and energy. I'm inspired by it every day! Glad to help when I can.

Re videos - Yes, I will try to post a few. I have screen capture, although never tried the ppt method.

Video is great, and Alan you are a master. Consecutive steps displayed in some of my "still" screen shots are admittedly not as nuanced or complete as click by click video. But they can show at a glance the progression to solution in a graphic shorthand. It's all good.

Another video hurdle for me is that about the time I get something figured out, others in the house are trying to sleep and don't want to hear me nattering on about issues with TAPs and DTMs. Or why a bi-rail sweep is rescaling the profile. Or, like this shelf one, why somehow along the way I managed to turn someone's innocent and nicely formed NURBS Surface into a twisted Tie Fighter. I need better planning of my video production schedule!

-B

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Benson,

You express the exact sentiments I have about making videos. It's hard to find the right time and place to create demonstrations of things, as well as making sure that you can represent your work in an understandable fashion. (I also, as many others, fear hearing my own voice in playback.)

Hopefully you, I, and all others with talent/things to share can get on top of it and start sharing our demos, greatly enhancing Vectorworks' user community.

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LOL, I know what you mean, I am fortunate that I have a small study so I can lock myself away from the kids and all and chat away.

Generally I don't really fuss about if it looks unprofessional its the content and if it gets the message across that's the main thing.

Sometimes it just a 5 min one to answer a question.

Anyways this is a great learning forum with fantastic and talented people willing to share and I thank you all for being around.

:) :)

Edited by Alan Woodwell

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