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Close Polygon Hole - Cut Hole in Poly?

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Hey there. I have created an extruded aluminum tube that is basically a square within a square and is hollow. Four lengths will make a frame (like for stretched canvas / picture frame) so I am trying to cut each end at 45°. I make the cut, and that removes the cap. I tried to use Mesh > Create Tools > Close Polygon Hole. This permits me to make two closures: 1) for the main outer edge and one for the inner edge (hole). But, they’re both covering up the hole now. Is there a way to use the inner polygon to cut a hole in the more outer polygon so that it returns to a tube?

To simplify what I am trying to accomplish, I recreated the problem by making a circle within a circle and extruding it into a pipe. I then cut the pipe and am left with a tube within a tube. I used > Close Polygon Hole on each cylinder, but the two discs that are created are opaque. As depicted in this screenshot, is there a method to cut a hole in the outer larger disk with the inner disc (making a hole)? I tried boole, but this didn’t seem to work I suppose because these aren’t simple splines?

I am so sorry I am not probably explaining this too well as the terminology and program are new to me. Usually do my work with a paint brush and tube of paint.

Thank you for your time.

extruded_aluminum.jpg

tube---cylinder-within-a-cylinder.jpg

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Hi Marc and :welcome:

can you upload a scene file?


| MAXON Quality Assurance | 3D Artist | C4D Cafe Manager | Gamer in Heart/PS4 ID: SIgor420 |:compEnjoy:

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Post moved to correct section (modelling / splines etc). 

 

It sounds like the Close Polygon Hole Command has simply failed on that geometry, which, TBH, it is likely to do when closing that sort of hole. The reason it can't work properly could be caused by one or several of many factors, all of which are quite complex to explain, but as it doesn't work, you need to manually help it along by placing some polys yourself in key places and before the shape is made editable, by making sure that your spline interpolation gives the form enough edges to work with...

 

As @Igor says if you upload the scene file, we'll be able to help a lot more and tell you which polys you need to bridge...

 

We should also ask if there is any reason you are not making the whole square profile at once, rather than in 4 separate pieces. Do they have to come apart in an animation for example ? Even then, it might be better to sweep along a rectangular path, and cut the geo up into sections after it has been made editable...

 

CBR

 

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  • Hey there Igor and Cerbera, thank you for the welcome.

     

    I am uploading the scene file you requested. This is a simplified file with only the problem portion.  There's a section for each of my steps so the file could illustrate my issue (and probably my ineptitude too!).

     

    The close poly tool seems to be doing an excellent job. I had read it can be problematic. My main issue is that it is not respecting the inner spline and creating a polygon that covers the entire hole.

     

    I am not sure if I understand the question about the creation of the whole profile at once. I am very likely going about this entirely wrong? I have only made it through a few rudimentary courses on Lynda.com and will continue on that front. But, my project deadline crept up on me.

     

    The animations would be very simple in demonstrating how these aluminum parts fit together, probably. I am merely demonstrating how to build an adjustable aluminum stretcher system I designed for artists--which is essentially a frame with supports. I could include the whole scene but thought this attachment would be easier? Please let me know if I did not answer that clearly. And, thank you so much for the help and offer to take a look. Very grateful.

    Talk soon,

    Marc

    Close Poly Hole.c4d

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    It is going to be very difficult to make this with splines because the amount of points on the inside is way different to the amount of points on the outside, so any automated process generating a surface between them has a high likelihood of error. Close polygon hole is a Polygon tool, and because these meshes were generated by splines, even though they are poly objects now they are not following the polygon modelling rules that would allow these sorts of poly tools to work correctly. 

     

    That sort of rules out using splines for this in my opinion, and you are left with the option of making it out of polys from the ground up, which will work with all the poly tools, but does require a higher level of modelling skill overall and a little more time.

    You can use symmetry to halve the amount of work you need to do, but essentially, you need to make a poly version of that first endcap, from which we can subsequently make everything else.

     

    Using your profile spline merely as a visual guide, I'll show you roughly  what that should look like when it's made out of proper hand-made polygons...

     

    Polysplines.thumb.jpg.8a76e6acd2e61c6951e32d4daf3b8280.jpg

     

    Once you have the cap as polys it becomes relatively trivial to extrude out a length of that then cut it at 45 degrees, at which point you can create the end cap on the angled part relatively quickly, because all the points will still match.

     

    CBR

     

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  • Wow Cerbera, thank you so much for the detailed explanation and getting me pointed in the right direction on this issue. That cut-away has so much more wonderful detail—I see there's a lot I didn't consider and I'll have to dig into the modeling side much more. Really appreciate your help! :)

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    I can save you a lot of work actually if I just give you my file, which you can easily make the right length by just grabbing the selected points and moving them on Z, which will do the other side as well because of the symmetry setup...

     

    1884915938_Frame45s.thumb.gif.d13785587f4a14374200dd81b246ebca.gif

     

    Polysplines.c4d

     

    Hope that helps

     

    CBR

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  • Wow Cerbera! Awesome animation showing me the expansion via the points. That is so kind. Thank you so very much for the help and the huge time-saving with this file. Beautiful work. Do you recommend any specific video or link for modeling like you've done here? Really interested in learning more about this as it's not been covered in the training I have encountered so far. Very grateful!! :) 

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    You're welcome...

     

    It takes a little while (several years) to learn Subdivision Surface / Poly modelling, so you won't find a single video that could possibly cover it all...

    But the cafe is a very good place to start ! Our own Jedi Master  @Hrvoje has done a particularly good series...

     

     

    Start modelling small, simple objects once you have a basic understanding of the tools, and you'll be well on your way. We are here to help with any specific challenges you face...

     

    CBR
     

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    Also check out CBRs own rocking gif tips, they are great insight into the methods and topology of modelling different shapes and real quick to digest as well as easy to scroll thru.

     

    Deck

     

    https://www.c4dcafe.com/ipb/forums/topic/101943-cerberas-rockin-gif-tips

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