View Full Version : Modelling an arch as part of a main mesh

01-28-2015, 01:48 AM
Hi everybody,

I'm trying to model this shape as shown in the pics. I need the arched piece to be a part of the main mesh and connected to it at both ends, as opposed to just a totally different mesh that's floating on it. What I've tried so far:
- Select a few polys on either side along the length and tried to bridge them; the bridge goes through the mesh and not like an arch over it
- Did a rail extrude by drawing an arc and extruding a selected poly along the spline; it forms a totally weird shape
- Magic bevel; same result as above.

I'm sure there is a relatively easy way to do this, but I haven't figured it out. Perhaps someone could assist?

Thanks very much.



01-28-2015, 02:06 AM
You need nice poly flow, since they're sub-patches..
You should adjust segments prior further work.
Then select polygon, and extender plus, then move, and again extender plus, move, then join parts.

01-28-2015, 05:16 AM
First off..you need to have the segments in one layer at the end when you are about to "fuse them" so a after you have positioned the handle over the main mesh, cut and paste it to the same layer.

second..the main tube, it has polar caps that are not quads, that is why you donīt get subpatches right and you get weird bulges, you need to triple the polar caps it or bevel it and then colaps middle point, then fix polar..or manually make it quads or with some, plugins that sort of divides it in to quads.
an option is to use catmull clark subpatches, that can deal with so called ngons.

to fuse the overlapping part, you need to bridge it, by selecting polys on the main shape and the end parts of the handle, here you have to learn how to bridge-connect segments, you can only do that in the same layer though.

you can also skip your premade handle part and use the bezier handle tool, you need to select two pairs of polys from the main mesh where the end and start of the bridge are supposed to be.

different ways of bridging..


One way to make your polar caps quads, select one polyface cap(not the two at once) go to subdivide triple, then go to construct merge triangles...then do the same for the other end cap.
Or..select the end cap and bevel with inset only bevel again with inset only, then construct/reduce collaps polygons.

02-01-2015, 12:41 AM
Thank you both for the useful techniques.

I was eventually able to use the bezier bridge to form something close to what I wanted. Will play around till I get it right.


02-01-2015, 12:33 PM
As you've found out, this is fairly simple. If your base object is symmetrically placed on the X axis, you could turn on SYMMETRY, grab one poly to Extend, drag it up a bit, EXTEND again, etc, until the relevant polys are above the base, then use Bridge to join.

Since you seem to be new, the trick is that EXTEND works immediately, so you don't have to switch tools to use it. The ROVE TOOL works particularly well in cases like this, because it combines MOVE and ROTATE in one tool. That allows you to tilt the Extend-ed polys towards each other incrementally so Bridge can work.

Because EXTEND works immediately, it seems like nothing happens when you hit its hotkey. Once you get past that, you can work really fast.

Short version: Use EXTEND and ROVE to do this fast.

02-01-2015, 05:02 PM
Ah, this is good to know. Thanks Jeric! You are right, I'm still new to working with LW, although I've had it with me for a few years.

I had tried a similar method, as suggested by Sensei, wherein I'd use extender plus to pull out the poly, rotate it a bit, extender plus again, rotate again...and so on until I reached the other end of the base. Then had to remove the poly faces on both the handle and base before welding the points. I found it a bit cumbersome, considering the amount of manual work involved in moving and rotating each iteration of the extender plus.

But like you suggested, symmetry would cut that time spent in half. Correct me if I'm wrong, but symmetry works only along the X axis, right?

02-01-2015, 10:02 PM
1) Yes, only along the X axis (left/right).

2) SADLY, and a huge bug IMO, the ROVE tool does not respect the Symmetry mode. (!!!) Huge bug. So my slickest trick here is nullified. A pity, since IMO Rove is a neglected and useful tool. (Axis Translate ALSO seems to not respect Symmetry, can someone confirm?)

Attached are screenies of a cylinder along the Z: some EXTENDING (not Extruding) and Move+Rotate got it to the first jpg, then Bridge made the final. All sub'd-- in real life something would have to be done about the n-gons at the caps of the cylinder.


02-02-2015, 02:36 AM
Thanks for showing this method. I was able to bring it up quite easily. So now I know that there are two ways to do this.


Rove is a new to me (I know it's been there for a while, but just haven't used it). It looks like a very useful little tool!

02-02-2015, 09:50 AM
If we go back to your original object, I think the problem is basically that the arch was a little low. It's geometry was intersecting the main tube thus making a bridge impossible (well not cleanly).
And, as you have learned from above .... in order to bridge, the geometries need to be in the same layer.


Your original..... notice the intersecting geometry. 126816

1) I copied the arch into the same layer as the tube and moved it up. 126817

2) You can bridge now.... but I thought the arch was a little too wide, so I just stretched it in to match what it's to join (see side view). 126818

3) bridge. 126819 126820

4) repeat bridge on other side. 126821 ...... OR, you can do the bridging in symmetry mode at the same time.

02-02-2015, 10:24 AM
It's probably worth mentioning: if you get something that's reluctant to bridge, drop out of subd for a moment to ensure that the polys actually face each other and are not 'behind' or 'past' each other, a situation that is easy enough to achieve when in subd.