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Extrude Polygons In A Cylinder

21 posts in this topic

Posted

I desperately want help to make a smooth slot inside a cylinder. I want the slot to go all the way inside the cylinder. I don´t know how to work with the polygons, and how to delete polygons at the top. Hard to get it smooth inside a HN. I,ve tried to make the slot with boole object, but it´s not good. Please, help me...

-ulf

slot.c4d

post-131834-0-18837500-1342733606_thumb.

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Posted

Hi ulf,

It's kind of hard to picture what you're going for, but I think the key info here is how the hypernurbs does its thing and what makes good topology.

Here's a scene file. It may not be what you're going for (reference image, maybe?), but you can see how I made cuts and moved points (etc) to change the way everything worked out.

I strongly suggest spending a modest sum on hsrdelic's Vertex Pusher tutorials--very helpful for understanding these kinds of things.

Hope that helps! Let us know if you have other questions.

~Whithers

slot_0001.c4d

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Posted

Hi ulf,

It's kind of hard to picture what you're going for, but I think the key info here is how the hypernurbs does its thing and what makes good topology.

Here's a scene file. It may not be what you're going for (reference image, maybe?), but you can see how I made cuts and moved points (etc) to change the way everything worked out.

I strongly suggest spending a modest sum on hsrdelic's Vertex Pusher tutorials--very helpful for understanding these kinds of things.

Hope that helps! Let us know if you have other questions.

~Whithers

Thank you. Still wonder how I get rid of unnecessary polygons after extrusion. Attaching a ref-image (Boole).

Hi ulf,

It's kind of hard to picture what you're going for, but I think the key info here is how the hypernurbs does its thing and what makes good topology.

Here's a scene file. It may not be what you're going for (reference image, maybe?), but you can see how I made cuts and moved points (etc) to change the way everything worked out.

I strongly suggest spending a modest sum on hsrdelic's Vertex Pusher tutorials--very helpful for understanding these kinds of things.

Hope that helps! Let us know if you have other questions.

~Whithers

Thank you. Still wonder how I get rid of unnecessary polygons after extrusion. Attaching a ref-image (Boole).

post-131834-0-89870400-1342777246_thumb.

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Posted (edited)

post-74060-0-60941000-1342784993_thumb.p

If this is what you are looking for, I wouldn't extrude it at all (at least not that part) I'd:

1. Create a cylinder without caps and then make it editable.

2. Close the Polygon hole on one end. (This will create a "can")

3. Select all the Polygons and extrude them to give the "can" some thickness (Extrude it twice so you get a subdivision in the top )

post-74060-0-25847100-1342785651_thumb.p

4. Delete the polygons on the top & inside where you want the cutout....

post-74060-0-03714200-1342785710_thumb.p

5. Select the EDGE on the bottom of this area and extrude it back into the can to create your base for the cutout (You need the edge & points for the next step)

post-74060-0-78088300-1342785822_thumb.p

6. Then, using the bridge tool connect each of the 3 sets of top & bottom edges of this region.

post-74060-0-99090000-1342785857_thumb.p

This isn't very efficient I suppose if you have a lot of sections to do, but works well for one or two.

Hope it helps.

R

Edited by RusKern

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Posted

I strongly suggest spending a modest sum on hsrdelic's Vertex Pusher tutorials--very helpful for understanding these kinds of things.

I second this, I am going through Vol. 1 right now and it has helped me a ton to understand how to get through things I could not before and also what I was not doing right, highly recommend you check these tutorials out.

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Posted

I second this, I am going through Vol. 1 right now and it has helped me a ton to understand how to get through things I could not before and also what I was not doing right, highly recommend you check these tutorials out.

I´m doing the same thing, and I strongly agree with you. It´s great lessons.

-ulf

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Posted

Thank you, existe. I want to have 4 slot/rails (my english could also be better) for inner walls who can slip down in to my cylinder. Therefore I have to make new edges. I´ve tried to bevel the axis centre edges into 2 new. That makes some messy geometry. It´s also difficult for me to know how to delete polygons so I get nice and sharp rails in a HN, without adding that may cuts. Another question is how I shall cut in order to get it right in the HN. If I loop cut, I´ll get deformed geometry on the outer side of the cylinder. If i line cut, I´ll get disturbing n-gons. Suggestions? Solutions?

-ulf

post-131834-0-05959900-1342938942_thumb.

rail.c4d

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Posted

Why not build the inside surface as a separate object, complete with the slots, which you will later combine with the exterior into a single object? OK the caps won't be there but you will be able to create these afterwards with the Bridge tool or Stitch and Sew.

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Posted

Why not build the inside surface as a separate object, complete with the slots, which you will later combine with the exterior into a single object? OK the caps won't be there but you will be able to create these afterwards with the Bridge tool or Stitch and Sew.

Thanks. I will try that. Probably you will hear from me again. By the way, makes me happy to hear your scottish accent. Went to Glasgow a couple of years ago. T´was raining every day. One early morning I was running under a bridge with a swedish flag on my wet cap, when an excited old man stopped me and thought I was Henrik Larsson. Wonderful city.

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Posted

Made this from a disc. Thougt I do as you suggested, delete the old border and bridge this one to the cylinder. Did a 0-extrude and moved it up with bottom cap. Line cuts and repositioning points. But when I do loop cuts in order to shape it up in the HN, it gets really messy. How shall I do it? Close to despair.

-ulf

new wall.c4d

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Posted

Naughty naughty. You're using R13 not R11 as in your profile. You should update your profile so that people know how best to answer. When I made the video earlier I deliberately used my old R11.5 so the tools would be appropriate and you would be able to open the scenefile.

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Posted

Naughty naughty. You're using R13 not R11 as in your profile. You should update your profile so that people know how best to answer. When I made the video earlier I deliberately used my old R11.5 so the tools would be appropriate and you would be able to open the scenefile.

Sorry. Just updated both version and now my settings.

-ulf

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Posted

Is it possible for me to clean up the geometry and get rid of the artifacts on the outside? Can I, in that case, use this object to Stitch and Sew it on my can?

-ulf

wall3.c4d

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Posted

Not sure what you mean by artifacts. All I'm seeing is the curvature isn't right because of the extra downwards edges. This can be fixed by moving some points in the X axis as shown in the image below.

What you need to strive for as well is maintain 4 sided polygons. There are situations where using 3 sided polygons gives the correct edge loop flow however. I think your model has more edge loops than what's required. You've then got some of those edge loops running out and joining others i.e. where the 3 sided polygons are.

3DKiwi

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Posted (edited)

I'm going to offer you a different approach that avoids disrupting the regularity of the external surface of the wall which is what's giving rise to the artefacts. 3DKiwi alluded to this in an earlier answer and how in C4D you will often have to nudge a new edge into a more comfortable position for the hypernurbs, but there are other ways.

Here's a preview, no artefacts.

Until C4D get's updated modelling tools like Modo's option to preserve the curvature of a subdivided surface (C4D's hypernurbs) when adding cuts we have to resort to such subterfuges but it does make you think about topology.

Here's how:

Edited by SKP

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Posted

Is is possible to express this kind of greatfulness? I´m learning, a lot... Thanks... will probably return in this subject...

humble-ulf

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Posted

Worked just fine. Exactly how I want it. Thanks. Now I wonder how I shall connect this two objects. I have deleted the the wall polygons on the can. Shall I place the the new wall in the can and Connect Objects? Or shall I use Stitch and Sew, or the bridge tool? Do I need to make the wall HN editable?

-ulf

can_new wall.c4d

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Posted

This is not your scene but since you have the same number of segments on the upper and lower parts where they will come together why not rotate the inner loop on the flat ledge 5° to line them up. Twisting a flat plane will produce no unwanted artefacts. Twisting the cylindrical wall will.

Combine the 2 meshes and Stitch & Sew to close the gap.

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Posted

I think I got it, almost... I manage to connect the two objects on the top, but at the bottom. Do I need to do that? Am I supposed to make the the two HN editable and connect them? Or can I store them in a Null Object? After modeling the inner wall, with great help from your excellent video, I noticed a black spot on the top of the rail edge. How can I get rid of that?

-ulf

post-131834-0-53010300-1343312991_thumb.

can6.c4d

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Posted

The black spot is probably a degenerate polygon. In the first video I posted on YouTube I dealt with one of these, 5:44 to 5:54.

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Posted

Thanks again. I´m learning so much. Is there a way to make the rail-wall without turning it 5 degrees. I want the rails in 3, 6, 9 oct 12 0´clock position. Is it possible to work with the existing 3, 6, 9 and 12 o´clock edge? Bevel it in to two edges or something...? Or maybe in some way make the rails on the original can-wall?

-ulf

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