hi
I'm wondering if it's possible to bend an object somehow. Let's say I have a flat oval shaped metal-plate and I want to bend it to a 180° curve. Is this somehow possible?

Thank's for any hints
nos

Hi nos...

Can you post your 3dm model here,,,

Hi nos, do you need the sheet after bending to be geometrically accurate, if so then MoI hasn't got any tools like in dedicated CAD programs which have speciality sheet metal tools to do bending/unbending accurately, Michael is planning to implement some deforming tools in the future.

If you need to bend the oval sheet just for a render or visualisation then it is possible to manipulate the control points of a surface to achieve what you want, a little planning would need to be done before you start, we're not exactly sure what you want to achieve unless you have a picture of some sort and then maybe the forum could help out.

Cheers

Hi nos, as Danny says above MoI does not currently have any tools to deform a solid that you have already created.

Typically the way such things are done is to draw it in the bent position right from the start. Or as Danny mentions with surfaces rather than solids it is possible to manipulate the control points of the surface to deform it.

If you could post a sample model that shows more specifically what you are trying to do, that could help to offer some additional tips.

One way that can work currently to bend your models is to import them into Rhino - Rhino uses the same 3DM file format as MoI and it has some tools for deforming solids like bending them. So you can import your model into Rhino, perform the bend in Rhino, then import your model back into MoI again. You can also use Ctrl+C / Ctrl+V copy and paste to move models back and forth between MoI and Rhino.

- Michael

HI
Thank's for the replies. Generally I use moi3d as a cad tool. So I design my models so that they can be manufactured. One of the methods is making flat object with a final contour in the first step and after that bending it to the final form. Sometimes it's not easy to determinate the contour or the location of other elements (like bore holes, cut-outs) of the flat object. So it would be nice if I could model the contour first and bend it afterwards, or even better do it similar to the sweep function where I can manipulate the curves an see the result on the fly.

I attached a image and the moifile.

Some basic deformers would be very welcome. :)

Is this something planned for the next version?

Here is a bit more complex version. The red curve should bend around the blue object.

Hi nos,

> Here is a bit more complex version. The red curve should
> bend around the blue object.

Actually, that's substantially more complex since you're talking about an uneven kind of bending there where it would try to adapt to the changing shape of that blue object.

Currently your best bet for these kinds of deformations is to use Rhino v4 to do them: http://www.rhino3d.com/ - you can import your MoI Model into Rhino and then use Rhino's FlowAlongSrf command to apply the deformation to your object. Then you can export your model out of Rhino and back into MoI.

See here for an example video:
http://tips.rhino3d.com/2009/02/learn-how-to-use-command-flowalongsrf.html

- Michael

Hi Andy,

> Some basic deformers would be very welcome. :)
>
> Is this something planned for the next version?


Yup, it's pretty high on my list of stuff to try for v3.

However, it is a somewhat difficult process to transform a NURBS solid and still keep all the pieces joined together - one reason is because the edges where the various surface of a NURBS solid touch each other can be at trim curve edges and not necessarily aligned to the underlying surface's control point structure.

See here for some more info on underlying surfaces and trim curves:
http://moi3d.com/FAQ#Q:_Why_does_show_points_work_for_some_objects_but_not_others.3F

So because of that kind of surface structure it means that you can't transform a NURBS solid just by transforming all the control points of each surface in the object, which is very different than transforming a polygon mesh object where you can just transform all the vertices and it's done. Instead with the NURBS transform all the surfaces have to be kind of refit with a new surface.

The Solids++ geometry kernel that MoI uses did recently add in support for this kind of deformation stuff, which I hope I will be able to use to add these kinds of deformation tools into MoI v3, but I have not yet had a chance to dig into them so I'm not sure how well they work yet.

- Michael

Numbers of control points are they modified?

Hi Pilou,

> Numbers of control points are they modified?

Yes, definitely - otherwise things like a plane that only has 4 corner control points would not be able to be deformed.

That's one of the problems with these kinds of deformations though, that it can tend to increase the complexity of the surfaces quite a bit by having a lot more control points in the deformed result.

- Michael

hi michael
I did try this with rhino but it seams I miss something, cause the result is shrinked. Do you have any idea why that is?
~nos

If I use the "Plane" Option it works, also paste back, very nice.








But no luck with the pre-defind surfaces.



I attached 3dm file.

~nos

if I use the Plane-Option in rhino but give it the same shape as the base surface the object get stretched along the target surface and dosn't keep its original size.

Hi nos - so that shrinking effect is happening because that one plane surface is a trimmed surface. The underlying surface is actually a fair bit larger than just the trim curves, and the way that Rhino's FlowAlongSrf command works, it just uses the underlying surface directly and doesn't pay any attention to how it is trimmed.

To see the underlying surface, in MoI select that surface and then turn on control points and zoom out a bit and you will see the 4 corner control points for it.

Because the base surface is actually fairly large, that then makes the result in your target surface to be small since the object being morphed is actually small in comparison to the base underlying surface.

There is some description of what an "underlying surface" and trim curves are here:
http://moi3d.com/wiki/FAQ#Q:_Why_does_show_points_work_for_some_objects_but_not_others.3F

So to fix it, select that surface and run ShrinkTrimmedSrf on it, either in MoI or in Rhino. In MoI you need to press the Tab key and type in the command name, or set up a keyboard shortcut for it, it is one of the commands that does not have a button for it in the UI yet.

Running ShrinkTrimmedSrf will shrink the underlying surface down to the trim curves so that it will be the same size as the trim curves and should behave more like you were expecting.

- Michael

HI again
I played around with Rhino and as far I understand, the size of the aligned object terminated from the relation of the size from base- and target surface.

I also found out that I can move the base surface to change the position of the aligned object and change the vu direction to change the rotation. But if the target surface is a complex object it seams not possible to find the same size for the base surface. So I have no clue how I have to keep the size from the base object.

Also finding the exact position. The position should be the same as the base object, except that it should be aligned to the target shape. Do I miss something. What I would except is that I could set some sort of anchor points on the base object and the target surface witch would be on the same position and determinate the location. Hope that makes sense.

Has anyone an idea how to achive this?

Thanks for any help.
~ nos

Ah, I did also a post in the meantime. I did try the shrink command. But now it's to big. So could you please explane what determinates the size and the position of the aligned object (beside the trimming).

Thanks for pointing this out
~nos

Hi nos,

> So could you please explane what determinates the size
> and the position of the aligned object (beside the trimming).

It just maps from the base surface to the target surface, but as I mentioned above it uses the underlying surfaces for this mapping, so look at the full untrimmed surface (one way to see it is by turning on control points) to see what will actually be used for the mapping.


> But now it's to big.

So that means that you want to increase the size of the base surface plane - scale it up or something so that the object you are deforming is contained inside of it with some space around it rather than having them right snug up against each other.

The same relationship of the object being morphed in relation to the base surface will then be applied to the target surface. That includes spacing, so increase the spacing around the base surface to then apply that same spacing to the target surface.

- Michael

> It just maps from the base surface to the target surface

ok, but what's the size of the target surface? Cause when the size of the aligned object is the result of base-surface/target-surface and I have to keep the size of base-object and the aligned-object the same, I have to figure out the size of the target-surface.

~nos

Hi nos, the size of the target surface is... well, it's size.

Every NURBS surface has a 4-sided layout to it the same as your plane there, with a closed surface it's just like you have a sheet of paper that is rolled up so that 2 of its edges are touching one another.

If you can imagine that sheet of paper being rolled up into the shape of your closed target surface there, the size is the size of that sheet.

So also the "seam edge" of the surface (where 2 of the edges of the rolled up surface touch each other) is significant - that will map to 2 of the edges of the flat plane. You may want to use the SrfSeam command in Rhino to move the seam to some other spot if you want your placed surface to start in some other spot than the current seam.


re: keep the size the same - that's generally not possible to do with these kinds of morphing transformations. A surface is not restricted to only have one fixed size in a direction, it can easily have things pinched together in some areas and be wider in other areas, and with your bendy surface it looks like you have that kind of a thing since it isn't just one single rigid shape in one direction of it.

If you wanted to preserve the size, that would require some kind of evenly shaped target and not one that was stretching and deformed in different areas of it.

- Michael