SubD and Mesh edge duplication and extrusion confusion

Hi RMA team,

I just made a quick video trying to show how something as simple as extruding a Sub open boundary, or a mesh open boundary, in an angle, and then tapered all around, and it seems perplexingly complex.

Making this simple video the extrude ball in the gumball just stop showing up, so I could not show you that. And the mesh edge duplication is doing nothing, and I crashed along the way mid video.

Also trying it before the video: extracting a control polygon of this open SubD gave me a closed mesh!

What am I missing? Why is this all so bad and wonky?


it’s very simple.angle

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You are completely missing the point of effective modeling. The line was drawn there ONLY to show direction in the video. Imagine how silly would be that you would actually have to draw that line every time you want to extrude with taper?

How is that simple compared to ‘ExtrudeCurveTampered’?

Also did you miss the fact that the extrusion ball was not even showing up in my video?


It’s not stupid, it’s stupid when you can’t push it out at the right coordinates. If you want to squeeze out exactly, you need a point or a line, or any landmark.
If you want to squeeze into space, then you don’t need anything.
And about the gumball ball I think I did not write to you, and was not going to write, or show. As you can see in the plot this gumball ball is present, it has not disappeared.

hi RMA team,

I made a video explain all the crazy steps I need to do vs. what it should be done.

Right now I require 16 very well coordinate (and requiring knowing all these tools) steps to just extrude tapered a SubD boundary if I want precise angle control:

  1. _ExtractControlPolygon from SubD (output stays selected, that’s good)
  2. _DupMeshEdge
  3. option BreakAngle=0
  4. option All (output stays selected, that’s good)
  5. ExtrudeCvdTapered
  6. option DraftAngle (input stays selected, noyt output, why???)
  7. SelLast
  8. Explode (its a polysurface and you cannot extract control poly of polysurfaces, for no good reason) (output stays selected, that’s good)
  9. _ExtractControlPolygon (output stays selected, that’s good)
  10. _join (because separate surfaces extract separate meshes, why we need polysurface support for ExtractControlPolygon)
  11. Shift-Select original Extracted control polygon
  12. Join
  13. ToSubD
  14. Unselect output
  15. go hunt for and select 1 SubD, 1 curve, 5 surfaces, 1 mesh that was left behind as construction steps (your hunting my vary depending on how often you manage to tell Rhino to delete input in your steps creation)
  16. Delete

We need to have a way to do _ExtrudeSubD with a proper direction, that is not just Free/X/Y/Z:
Here we need to add a _direction (where we can pick start and end of the direction vector) and a taper amount if we want to taper by angle, instead of liner extrusion in a single direction)

We should also have this Gumball option for angle input:

extruding_tapered_a SubD_adventures_gf_200806.3dm (202.0 KB)

Please let me know what you think,


I never said stupid, rather silly. In English they have very different meaning and impact. I might use stupid when something is aggravating and purposefully neglected. Here’s this is just not paying enough attention to polish tools as usual by McNeel’s early development process. And I’m here to help on that front. What are you here for?

I know the McNeel team will trust me and give me some credit on my honesty, skill and cognitive ability to claim that a tool was not working reliably right before doing so in a video. This is useful in case they hear others claiming such thing and they can start establishing a pattern for a fix. I would not say such claims lightly, I know the burden such claims can put on developers, their work, their stress level, their responsibility and their allocation of resources. It doesn’t matter what you think about it, you are borderline trolling now, stop it please.


I will leave unanswered, or I will again get the troll label. :wink:

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so add an angle option to the existing extrude command?

you could have saved a lot of typing… :wink:

the workaround for now would be-

i’m wondering if you have two identical subd’s stitched together and that is why is said it was s closed mesh… the extrude ball dissapears on internal edges, which leads me to believe you have two objects on top of each other and your edge is actually not an open edge. The behavior I’m seeing indicates something wrong with your mesh not necessarily the tools.

fwiw, drag + ctrl lets you drag the cplane icon in any direction you choose, but not at a specified value.
you could use gumball and osnap to extrude precisely to a guild curve, but I agree that is a bit of a pain. workaround2

I will write up the add for angled extrusions.

Thanks Kyle, do you mean I could have asked the wish and post? just like that? no showing receipts? not showing my homework? not even my 16 steps of itemized deductions?

I like this new approach!

Please keep in mind that I’m asking for 2 things:

  1. Extruding all at a specific direction (that would be adding a Dir option to ExtrudeSuD that allows us to pic a user-defined direction, not just the X, Y or Z vectors, same as the _ExtrudeCrv command.

This is what _ExtrudeSubD lets us do:


This is what _ExtrudeCrv lets us do:

D Enter:

  1. Extuding SubD with Taper

Regarding these workarounds:

I played with that and I can get them to do even more, but the scale handles not being fixed to the bounding box of my selection do not allow me to have precise snapping. Any ideas why this is happening?

Even if this gets fixed, of course this would only works with rectangles that are orthogonality placed in world XYZ, so it’s not very useful for real production work, but it might come handing for very simple work.



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yep- totally agree with your notes above.

to be clear, the benchmark for v7 was to have stable, functional, usable SubD. I believe we are there now. As v7 moves forward, I’d expect each service release to have incremental changes and improvements. SubD is now a 1st class citizen of the rhinoshpere and as such will continue to grow and develop as time marches forward.

So Will this get added for the v7 release? maybe. but likely not.

will it get added at some point, very likely yes.

as for the comments about scale handles and orthogonal alignment… remember you can ctrl+click modify any part of the gumball (scale handle length, gumball location, gumball rotation) to set it on any trajectory you want…

a possible workflow for your needs: (admitting this is too basic for many circumstances, but little wins are little wins)

click a face, ctrl+click a rotation handle to add a specific angle, then extrude by dragging then holding ctrl.

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The exact binding the handle scaling is included in the - Points ON mode. Without point mode, fix the positions of the handle scaling through Ctrl, I’ve shown you before in the gif.
Through Shift pull at two coordinates at once.

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Thank you Kyle and Inju for the feedback on Gumball Ninja work.

Kyle, I think it wold be great to have a new video of Gumball functionality, including how to edit it, and what kind of numeric inputs understands. But probably that should happen after @pascal’s idea of checkbox to enable/disable scale/rotate/move sub-handles is implemented. I think this is scheduled for the week after next’s build, correct?

Sound good to me, I say you ship V7 next week and Jackie can upgrade all our licenses. We are in Rhino Subscription at an emotional level. And we have been using V7 exclusively for a few years now.



I think Brian James Classic “hello Gumball” is due for an update!

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ctrl + click lets you rotate the C-Plane numerically

And the scale handle can already be turned off by entering size 0 in the settings. Personally I prefer having the option to choose in between translation, scaling and rotating on a single gumball rather than having a different mode for every operation like in T-Splines.

Multi gumball however would be cool!

yes, and that only works for when you want to rotate all in the same direction.

In this case I wanted a local /taper rotation, so each side here is rotated in 4 different orientations:


And that’s just a simple cube with straight/perpendicular walls.

We need extrude with taper and we also need local + element directions/angles for gumball.


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In that case shown, you’d simply extrude straight up 1st, then scale out holding shift, but I get what you are asking.

T-Splines had a UVN drag mode

Now all we’d need is multi gumball, right @gustojunk?

yeah, that case is the type of stuff I do not design for a living. I only create it to show as example. I would be bothering you all a lot less if we designed and modeled just boxes.

Actually if we only designed shapes like that we wouldn’t need to use Rhino superpowers at all, or need SubDs with faster/better tools. We could do it all in DS Booleanworks and ASDK Fashion360.

…but then life would be so boring for all of us.

Speaking of not getting bored, I made this video last week for your software development assistants. I hadn’t posted it because I don’t want you to think I’d expect this for V7. But if you promise you can wait to demand this from them until after 7 is shipped, here it goes:

Have a great weekend Kyle!


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100% agree falloffs are necessary. I’m already banging that drum as SubD develops.