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Move just single vertex of a cube?

android111
Enthusiast

Move just single vertex of a cube?

android111
Enthusiast
Enthusiast

Thought for sure this would be an easy one... but I can't move just a vertex.

 

vertex.jpg

 

If this can't be done, what are the typical methods?

thanks

 

Can this be done, and, if not, what's the alternative so that it can be modified later?

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laughingcreek
Mentor
Mentor

fusion is a brep/nurbs modeler. not a mesh modeler like blender.  a completely different world data wise.  and a completely different approach to model creation.   no you can't just "grab a vertex" and move it because the underlying geometry isn't a mesh.

if you can show a sketch or an object of what you want to do, I'm sure someone will give you some help getting there.

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android111
Enthusiast
Enthusiast

Thanks - the reference image shows what I'm describing.

FWIW, no issues doing this in Rhino, though their brep/nurb manipulation philosophy is a bit different.

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TrippyLighting
Consultant
Consultant

Blender is a Mesh modeling program. When you move that vertex the quad face is triangulated.

In the CAD world 3D geometry is represented by Analytical Geometry, or NURBS surfaces. In case of a solid model such as this cube, they are rolled into a BRep.


When you move that vertex, Fusion 360 would have to do a on-the-fly conversion from an analytical face to NURBS geometry. I don't know of there is a CAD software that does that. (I've not worked with Plasticity CAD yet).

 

As such you cannot simply move a vertex of a solid body in CAD software.

It's a lot more complicated to achieve that geometry!


EESignature

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TrippyLighting
Consultant
Consultant

@android111 wrote:

Thanks - the reference image shows what I'm describing.

FWIW, no issues doing this in Rhino.


IIWA (It Isn't Worth Anything, LOL). Rhino is great software, but is isn't parametric.


EESignature

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android111
Enthusiast
Enthusiast

Thanks Peter - Plasticity does not do it, which is part of what brought me here!

 

As noted - Blender does it effortlessly, though may result in wonky geometry.

That said - it's useful to be able to do this to prototype, even/especially to create a "guide" to use to properly build an object.

I'm not so concerned with the hardship a computer has to go through to figure out how to do it ๐Ÿ˜‰

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davebYYPCU
Consultant
Consultant

Yes and no,

Thereโ€™s a work around, 

Form - Box, with creased edges, manipulated to that shape, 

Will bring with it the Rhino limitation of not being a parametric result.

 

Might helpโ€ฆ.

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etfrench
Mentor
Mentor

Patch works with two sketches.  One to position the offset point, and the other to connect the bottom point to the offset point.

etfrench_0-1698380984205.png

 

ETFrench

EESignature

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MichaelT_123
Advisor
Advisor

 

Hi IRobotโจAI Android111,

 

Let us think together a little bit about the title.

'Move just single vertex of a cube'

'Cube' is a topological object defined by three pairs of parallel planes, creating 12 edges and 8 vertices. Without dissecting the topology too much, let's notice that intersecting plane triplets topologically constrain all vertices. It means that it is impossible to move any of them without changing the topological class of the original object, a cube in this case.

Thus, no one can move a single vertex of a cube!

In order to allow such a trick, we must change the domain (class) of the object. One way to do this is to enable pseudo-cube faces to be non-planar and force F360 to alter their internal representation from planes to NURBS surfaces.

I see two evident and straightforward paths to achieve such a metamorphosis at the UI level (API is also an option, but ignore it here).

  1. Create a cube and manipulate its vertices using the Form environment.
  2. Create a pseudo-cube via sketch, surface patches and stitches to brepBody.

The first method is not parametric.

The second method could be parametric (see the attached file) via sketch dimensioning. Furthermore, the resulting topological outcome could resemble operations as in Rhino or Blender. Why? โ€ฆ Because both software are masters of juggling 3D topologies by means of NURBS surfaces!

CubeMoveVertex.png

 

Regards

MichaelT

 

PS.

I was tooooo late! M.ETFrench was quicker! Congratulations!

MichaelT
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TrippyLighting
Consultant
Consultant

 


@android111 wrote:

...

As noted - Blender does it effortlessly, though may result in wonky geometry.

...


The topology of a more complex CAD model than a cube (a blend of Analytic Geometry and  trimmed NURBs surfaces) is completely deferent from a Sub-D/Polygon model. 

These different types of geometry require different modeling tools, although there can be quite a bit of overlap. Plasticity CAD is a very good example of a blend between traditional CAD modeling tools and Sub-D/Polygon modeling, which is why I referred to it.

 

If you know how to model in Blender it will not result in "wonky" geometry, but it will still be a mesh model, not a CAD model.

 


@android111 wrote:

...

I'm not so concerned with the hardship a computer has to go through to figure out how to do it ๐Ÿ˜‰


You should! Otherwise your models are going to suffer from performance problem's!

It also isn't so much the hardship of the computer, because obviously without  a lot of math, computer science and programming the computer wouldn't do a thing at all.

 


EESignature

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TheCADWhisperer
Consultant
Consultant

@android111 wrote:

Thought for sure this would be an easy one... but I can't move just a vertex.

what's the alternative 


@android111 

Oh, I like these easy ones.

TheCADWhisperer_0-1698404905428.png

 

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JamieGilchrist
Autodesk
Autodesk

Hi @android111 ,

the answer is both yes and no for the many reasons stated above.  Fusion is primarily a parametric CAD modeler that produces more rigid analytical solid and surface bodies.
That said, you can do this in Solid, Surface or the Form workspaces (as @davebYYPCU stated)

I'll attach my example.  But it's important to note that you have to understand the limitations of a parametric modeler, the overhead it imposes on modeling, and how to negotiate "around" it to get the result that you are aiming for.

For this example, I created two sketches to represent the boundary of the box ("cube"), note that I removed all the constraints from the curves except for the coincident constraints at each adjacent line endpoint.  I know this will give me the freedom to move those pairs of points in coordinate space as I wish.

Screenshot 2023-11-03 at 10.06.07 AM.png

Then create two lofted faces (using the corresponding opposite curves for the inputs) for the inputs of the main lofted body of the box.  Note that Fusions modeling kernel will accept sketch profiles or surfaces/faces as inputs for lofts.  However, if you pull a sketch out of plane (i.e. one point of a rectangle is not on the sketch plane) the profile will fail and so will any subsequent features.

So I used the two surface bodies (Body1 and Body2) as input for the solid loft.

Hint: turn off the sketch visibility, when building the loft to make selecting the surface bodies easier)

Screenshot 2023-11-03 at 10.07.17 AM.png

Now turn on the visibility of the sketches and Move vertices to change the shape of the box

Screenshot 2023-11-03 at 10.10.26 AM.png

 

You now have a parametric box that modifies as you expect.  it is important to note that while it is parametric, it is nowhere close to being fully defined, this makes some designers and engineers uncomfortable proposing this workflow, but I've seen it used quite successfully for conceptual work.

โ€ƒ

โ€ƒ

hope this helps,


Jamie Gilchrist
Senior Principal Experience Designer
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