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How to turn a rectangular object into a cylinder?


Maarten Vis

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Hi guys,

 

I want to create a vase that has a non-repetitive pattern cut out from it on the surface.

 

The pattern will be created in 2d, so I wil import it, extrude it, and then cut it out from a rectangular surface. (I've made a simple example to show what I mean.)  But then I need to deform that rectangle into a cylinder. But how can I do that?

 

Thanks in advance for the help!

 

Maarten

 

 

Screenshot 2022-08-28 at 22.00.03.png

test.c4d

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  • Maarten Vis changed the title to How to turn a rectangular object into a cylinder?

Well the Wrap Deformer in Cylinder mode will do that, as would a Spline Wrap driven by a circle spline,  but crucially anything you import and extrude MUST have correct topology to be able to bend evenly, and the weak point in this chain is extruding external splines which gives you very little control over topology - in fact the only thing you can really do is choose delaunay type caps, which may give you a suitably deformable surface, but I suspect you will struggle anyway to produce flawless cylindrical deformation directly from an imported spline, because the radial segments must be EXACTLY even, or it won't look like a proper cylinder. Even Delaunay Caps does not give you this, and the only control you have over it is the intermediate points in the splines or the density slider in the caps options.

 

You can see in your reference pic from all horrible shading errors that the topology from this spline is not even suitable to produce a viable render undeformed, though this will be mainly because of phong settings and caps type in the Extrude. If we turn on ngon lines we can see the reason for this... does that look like it will bend properly ?!!

 

image.thumb.png.ecbcaf87c9c4109302a5abdbf6dc0709.png

 

I tested it to see just how awful it would be, so chucked a temporary -360 degree bend on it, which would be yet another way to deform it cylindrically...

 

image.thumb.png.e56dcfd1f2f851d41aa85ac26eda760a.png

 

As you can see, it is totally unable to even come close to a vaguely cylindrical result because there simply isn't the topo there to support it. So, forced into a cylinder as is, not only would this surfacing artefacting become orders of magnitude worse, but it can't even hold the basic shape !  And frustratingly there won't be much you can do about that with the rather limited controls of an Extrude Object, or even by Z-Remeshing it, which again doesn't necessarily return enough control to be able to get the topology you need.

 

If I get time tonight I may make you something which shows you the sort of topology you DO need for even cylindrical deforming, but I can tell you now you need as close as possible to exactly square polygons all over the mesh. And the pattern you have shared is a particularly difficult pattern to achieve that with because of all those highly raked cutouts at the top which will necessarily be running counter-poly flow. Lastly,  in order to wrap this successfully, there have to be identical counts and layouts of polys at both ends of the mesh or they won't meet up properly without a visible seam.

 

I think even people like me, with 25 years modelling XP behind them might struggle with that particular pattern, so if you are new to modelling this is... ambitious, to say the least.

 

I should also mention that using any deformer method mentioned above you don't want any thickness in the mesh until AFTER it is deformed ideally.

 

If this was my project, I would import the spline, but then use it only as a visual guide to model a suitable flat surface properly, out of polys, so that I had specific control over the layout of every single polygon in it. That is the only way to guarantee a perfectly rendering result, unless you are able to get it via different methods entirely, like for example using the Volume builder and its smoothable boolean functions. The price you pay though using that method would be the incredibly dense mesh a VB setup outputs, which is unlikely to be re-meshable to more reasonable numbers without quite some manual effort to tell it which surface details it should keep sharp.

 

CBR

Edited by Cerbera
Added info, pls refresh page (see edit history)
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Hi Cerbera,

 

Thanks for the reply, very instructive! I was afaid this would be a very complex thing to pull off.

 

That example pattern I put together really quickly and I guess it was not a good example. The final pattern would be more similar to something like the attached.

 

Would that make it more achievable?

 

Cheers,

 

Maarten

 

 

Screenshot 2022-08-29 at 10.41.03.png

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Ah yes that is an easier surface to make without doubt, but looks fairly random, and I am not seeing many repeating patterns in it so it would still be quite a lot of manual work to model this so it could bend properly.

 

But I don't think the results we'd get from modelling that would be much superior to if you just used an altered greyscale version of that image as a displacement map and did it with materials or even just a high density primitive and displacer deformer if you wanted it preview-able in the viewport ! If you want to try lots of patterns that seems an eminently more sensible way forward, or you'll be stuck modelling for hours !

 

CBR

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I did a  quick test with the yellow and white image you posted.  I just desaturated it and threw it into the shader in the Displacer.   It's just a flat plane with a lot of segments, displaced, SDS, then put a bend on it.   I thought about throwing the whole thing in a Volume builder to smooth it out but I have to start on dinner.  

 

 

image.thumb.png.ee846ac61cab1caa871ccae6254a6575.png

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one last thought.  you could convert this thing to an object, baking down everything (minus the bend).   So it would be a dense flat plane with the pattern.  Then use either a remesher or even further,  a retopologize strategy to isolate parts of the pattern, rebuild/remodel it then push it through a cloner or something to make a new flat sheet of the pattern, then use the bend tool on that instead.    

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