Hi Michael, an other happy moiers :)

Here's a little request, not sure if this specific tool will be valid inside the "MoI" philosophy, but it might be quite helpfull not only for me (I guess).
The tool would be a combo of



and will help to build nice tube/wire on surface.

Actually when I'm trying to create this kind of geometry, I have to use this workflow :

Here's the background


I'm using the freeform curve/ctrl points with only 'on surface' snapping


and finally I create the tube (Sweep)


Using that method, I always have half of the tube melted inside the 'collision' geomtry, it might be sometime usefull sometime, but I would
really love to have a more accurate way of doing it.


So, in my wonderland, the tube tool combo will allow :

1) Draw the tube in 'realtime' when drawing the curve, very handy (for me :P), but maybe to heavy to process.
2) The most important, having an Surface Offset snapping option, with a distance = the circle radius of the tube, to avoild the 'melting' effect.

Not I can imagine it's not that easy to do, and probably not a real priority off course, but in the meantime if it possbile to create a script that will allow me
to draw curve on surface with this famous offset option, that will save my day (and probably my week in fact :))



(btw I'm not asking to have any accurate offset a along the curve off course, only at the control points it's more than enough)

Thanks for reading !

Heurm thinking a little bit loud, in fact having just an offset distance for the 'OnSurface' snapping will be the better solution, so I can even edit/adjust the curve after his creation and keeping the offset safe.

And "inflate/deflate" Copy before the "Plan Volumes" of an half diameter wished ? (Scale 3D)
Draw the curve
kill the inflated:deflated volumes
make the sweep ;)

@PaQ:Mais bon c'est peut-être du système D :)

Yes Pilou, that's the idea, but not very handy with 'complex' objects ... more over a real inflat is not a simple 3d scale, it's more a thickness/offset command, and that's quite heavy and not working very well with complex shape.

I didnt see it mentioned yet but at least half of this tool exists with petr's pipe script on the resources page.

No offset but the tube part is there.

Well not really, the pipe script 'only' create an hollow pipe from a curve, it's not an interactif pipe/tube creation ... and again, it's mainly the offset distance from 'onsurface' snapping that will really speedup this kind of job. (I actually have to draw thousands of tubes in an quite complex hangar scene :s )

Also seems more of an "on surface" snap offset as the pipe wouldnt always know the "touching" side of the curve. So tickcheck offset in the onsurf snap and do operation then when "ok", adjust points with offset?

[EDIT]
This didnt make sense but the jist was the onsurf offset being the main point you made
[EDIT]

Yes PAQ not interactive, just a little easier than sweep. I agree with the most important part is the offset. The sweep is easy either way!

I think he talked about the pipe tool in another thread. since sweep does it and gives you control over the sweep shape, then no need for special shape tool, (except in your particular case it would be a blessing) However, the onsurf snap is a great request I hope is possible.

Interactive sweep would be a feature that solves many areas including yours. I wonder if that is possible. Does ANY app have interactive sweep? (not just pipe but more "create sweep shape THEN draw sweep path")

Kind of like the way extrude works but with point picking and G1 G2 options and with directional rotation.

>> Does ANY app have interactive sweep?

I suppose you can do it in Houdini, as you can build and animate your own parametric tools. Maybe the 3dsmax stacking system allow this, but I'm not sure.
I don't know any other nurbs package than MoI :)

For the interactive tube, modo has something like that, only polygonal tubes create from 'a through points' kind of curves ... but it's not very handy, a 'control point' drawing method is much more natural (at least for me), and combine with the straight snap I can draw really natural wires/tubes in MoI. More over, not offset snapping in modo either for the tube tool.

I think we can allready forget the interactive sweep stuff. I just did a quick test in MoI, interactively change some curve's control points after a sweep (a simple circle as root shape) is allready really slow, and I 'only' have 10 control points on the sweep rail (and I use an angle 35° in the meshing angle option to speed up the process)

So 'just' the OnSurf offset option would be enough :P

Hi PaQ, yeah for NURBS a tube is a pretty complex object, mostly because of the focus on accuracy. The polygon tube will have some pretty substantial (as far as tolerances go) deviations in parts of its "surface" (facets) from the pure tube... With the NURBS sweep that surface is repeatedly subdivided until it has accuracy of 0.001 units from the "perfect" tube. The bulk of the time is in that refinement process and repeated tolerance checking. Poly modeling just pretty much skips all that tolerance testing.

Anyway - re: offset -

You don't have to do sweep with the rails only running directly through the center point of a profile.

If you place the circle so that it touches the rail only on one side like this:



Then when you sweep it, it will not be moved to the center, it will take the profile from where it stands and drag it along the rail:




Does that produce the kind of offset tube that you are looking for?

If so then you just kind of carefully position 1 circle to that orientation at the end of a curve and you're done... Don't use the auto-place mode for this, because auto-place will put it with the profile centered right on the rail.


re: Offset from surface while drawing - one way you can possibly do that now is to drag out a construction line on the surface normal before you place the point. You may need to do a little slight of hand to type in the distance before you finish the construction line to place the end at the distance you want. A kind of "running offset distance" is an interesting idea but may be somewhat difficult to set up, a surface normal has 2 directions on it and it may be difficult for you to predict which is the "positive" side on any given free-standing surface. So just setting a single value and then doing single pick, pick, pick after that probably would not do it properly, you would need to do something like 2 picks with the second pick indicating which side... Might be rather awkward to set up.


Anyway, does positioning the profile circle at the offset location work ok for what you need?

- Michael

Theres some good app info, thanks.
>>
I think we can allready forget the interactive sweep stuff. I just did a quick test in MoI, interactively change some curve's control points after a sweep (a simple circle as root shape) is allready really slow, and I 'only' have 10 control points on the sweep rail (and I use an angle 35° in the meshing angle option to speed up the process)

So 'just' the OnSurf offset option would be enough :P
>>

Yes, seperating out the onsurf offset suggestion, here I agree

(this is just me expounding on the interactive idea)
That makes sense, however, extrude seems fairly instantanious. Am wondering about "continuous extrude" where keep picking as you go??? Then also to expand here, the continuous extrude with the curve tool as opposed to the polyline tool, that doesnt create a "break" at each chosen point?

Make sense?

I think the slow part above is due to the recalculation of the entire obect when done that way. When done while drawing, theres much less going on "per pick" so it seems more like click, click, click.. instead of click wait.... click wait....!

The circle can be positioned quickly by use of Circle / Diameter, followed by rotate widget:



- Michael

Rotate widget. Nice!

I just did a sweep test and it followed the path through some surfacing turns exactly as expected, then right at the end point, closest to you in the picture, slide over on its side and sunk in to surace.

Is there something about that last point I picked that controlled this? Is there anything in this method that controls the "up" of my path or is it automated?

Thanks

Hi Burr, oops I forgot about the twisting.

There is a Twist: option in Sweep which allows you to choose between the standard minimal gradual twist, or a twist that only rotates around the world z axis.

Neither one will do a "Twist only around some various different normals of surfaces that the curve happens to come close to" though.

Aside from the twist parameter though you can add in additional profiles to control it.

Like if you repeat the circle positioning at the end so that then you have 2 circles, that would enforce the profile position at that area, possibly doing that at that spot and maybe 1 or 2 others would do the trick.


That would be a benefit of having the rail curve itself offset from the surface though rather than the profiles - it would be basically immune to the twisting, since the twist would be around a circle's center point instead of its side-quadrant point. But probably harder to set up the central rail curve though.

- Michael

Hi Burr, just another note:

> Is there something about that last point I picked that
> controlled this? Is there anything in this method that
> controls the "up" of my path or is it automated?

It's nothing about that last point - the twisting is due to the way the rail path travels around in 3D instead of being planar.

When a sweep profile curve is following a 3D path, there is a kind of gradual twist that happens to it as it follows up and down humps, etc... - it's something that helps each new positioned curve to be as minimally different from the previous one as possible.

If it didn't do that, it would tend to swing around more suddenly at some spots as it changed in orientation.

The "flat" twist option does it differently and only rotates around the world z axis. But there you will see the kind of sudden large jumping for paths that have a tangent that approaches that z axis direction.

- Michael

Hi Michael,

Yes I can understand having a realtime feedback for this kind of tool require much more power computing that simple polys.

About the offset :

I get the circle offset position before the sweep, however it only works for ground plane, but not when the driving curve has to touch different object, like the first image sequence I post, or for the little example here :



>> Offset from surface while drawing - one way you can possibly do that now is to drag out a construction line on the surface normal before you place the point. You may need to do a little slight of hand to type in the distance before you finish the construction line to place the end at the distance you want.

I see the idea, and I just try it right now, not very easy :S Probably a solution if I have a unique wire/tube in my model, but I can't imagine placing thousand of wire like that. More over it's also hard to edit the curve afterward (and keeping the offset of course)

>> A kind of "running offset distance" is an interesting idea but may be somewhat difficult to set up, a surface normal has 2 directions on it and it may be difficult for you to predict which is the "positive" side on any given free-standing surface. So just setting a single value and then doing single pick, pick, pick after that probably would not do it properly, you would need to do something like 2 picks with the second pick indicating which side... Might be rather awkward to set up.

Well even 2 click doesnt sounds that bad, I'm quite ease with the MoI navigation so I'm not that affraid by the awkwardness.
Just wondering too, isn't this double normal problem resolved when you works with solids ? It's a bit like the meshing process right, when a geometry is closed you can define where the normal is looking at. (Just a non pragramming lazy guy shorcut :))

>>
Aside from the twist parameter though you can add in additional profiles to control it.
>>
Still tunnel vision so the obvious escapes me! duh.

Adding the couple extra profiles made this work.

>> The circle can be positioned quickly by use of Circle / Diameter, followed by rotate widget:

Interessting method, but it requires a couple of more step if the sweep rail is more 'organic' like the rail I build above ... not so easy (impossible) to align the cicle/cross sections with the gizmo method when the rail is turning around something (helix).

Seems a solution indeed (in fact cross sections don't have to be align with the rail, so it's probably a little bit faster than I thought)

I will apply that tomorrow and see how it comes :)

Thanks BurrMan and Michael !