Hi there I been having some problem or maybe I dont quite understand the sweep tool properly


How many profiles can you use with 1 rail and how many with 2 rails

for 1 rail i can use 2 profile but there a tad iffy

for two rails I cant use more then 1 profile as nothing is generated

also when using 2 rail and a profile if I have corner points that breaks up the final result as per the corners on say a rail
is that normal? ie no corner points aloud ?

Any numbers of profil for 1 or 2 rails ! :)
I was like you the first time !
I believed that just one profil was permited for a sweep ! :)

Breaking form on the "corners points" is normal!
If you take a curve without "corners points" this will desapears :)

If you don't want the "hole" and have a "breaking form" as profil you must place your "horizontal profils" on the "vertical profil" and use the Loft function :)
Remark that you can choice "normal (curvy), loose, or here straight loft style!

The vertical profil is not needing for the loft, only for the position of the other profils :)

Hi Corzair - you can have any number of profiles.

But I think I see your problem - you're doing a one rail sweep with a bendy rail off to the side. This isn't good for 1-rail sweep because one-rail sweep will rotate the shapes as they move along the rail. This is why you're getting some strange results - there is a combination of rotation along the rail along with morphing between the profiles.

Although you can sometimes use a one-rail sweep with the rail off to the side, it might be clearer to think of it as a "spine" curve that should be running through the centers of the profiles. When you have your spine off-center, then any wiggles in the spine generate wider rotations to stuff that is way off of the side.

I will post some images shortly to clear this up some more.

- Michael

Oops, I see how that you're not doing what I was worried about (1 rail sweep with the spine off to the side).

Ok - let me start over again...

> for 1 rail i can use 2 profile but there a tad iffy
>
> for two rails I cant use more then 1 profile as nothing is generated

Can you please post some examples of these problems?

In general you should be able to use any number of profiles for either type of sweep. But during the sweeping process, MoI has to associate each profile with a spot along the rail(s).

For 2 rail sweep, if you have the profiles touching the rails then it will use those touching points as the associated rail location. But if they are not touching, it will try to find the closest point to the rail and use that.

However, if you have multiple profiles and they do not attach to the rails in a consistent manner (like if they are mixed up in order or something, such as the 3rd profile attaches at a point behind the 2nd one), then that will cause the sweep to fail.

I see that some of your sweep examples here have the profiles a fair distance away from the rails, so you may be running into something along those lines, if you can post an example I can tell for sure. You can fix this up by placing the endpoints fo the profiles right on the rails to give MoI a clearer indication of which spot on the rail a profile should be attached to.


> also when using 2 rail and a profile if I have corner points that breaks up the final result as per
> the corners on say a rail
> is that normal? ie no corner points aloud ?

Well, they're allowed but yes they will currently result in the sweep being broken up into different pieces for each segment.

Eventually I should be able to improve this to work more like you expected, but probably not until version 2.0.

In the meantime to build a shape like you want there, you can cut out an equivalent segment of the circle rail, then sweep just one piece, then array that to make the full set of 8 matching pieces:



- Michael

There is a bad sweep and a good sweep :)
But I am not sure that the result of the circular array will be the good piece?
Transition between the arc to the side of polygon will be the same following bad sweep (if surfaces are not cracked) or good sweep?

Hi Pilou - yup, you don't want to use the segmented sides as the rails, because then you're just back to the segmented-rail problem again.

> Transition between the arc to the side of polygon will be the same
> following bad(if surfaces are not craked) or good sweep?

Yes, the shape along all the edges should be the same in each case - but the internal parts are different.

Even later on when I can make the segmented sweep better, it probably won't be as good as the "good" sweep in this case though - there's sort of an issue of what to do with the profile in the transition between the segments - should it be extended and intersected? Maybe an averagead rotation between the 2 different directions? The abrupt shift of direction in the rails makes it hard to do something good there for all cases.

- Michael

So curves seems better and sweet than broken lines :)

Sweep also accepts a stop and start profile, and 1 or 2 rails. So you can force how the surface starts and terminates. By judicious use, you can use then to sweep a segmented curve.

Tricky indeed!

Thanks for the clarifications

I was trying to get the hang of the sweep function - thats what the examples were, a way to try and teach myself

I think in Amapi so was confusing my self, once you get gorden surface that'll be huge to ;-)

thankyou M
and all for your quick responces

hmm still having problems with more then one profile for sweeps


see example of hull/fuselage type shape

just cant do two profiles

Hi Corzair, it looks like a bug for this particular situation where you have the rails touching at a point and the rails also stick out past the shape on the other end.

I should be able to fix this up, but in the meantime if you add an additional profile snapped on to the ends of the rails it should then work.

- Michael

I'm struggling to get my finger out. (see attachment)

It's made of two rails and a two profiles. It fails to sweep.

I've just come to assume that if something fails then it's probably because I'm asking too much of MoI, and not that it's a bug.

Hi Wibble - looks to me like a bug, can you please post the model file?

Looks like it may be related to the bug from earlier in this thread.

- Michael

Okay, you asked for it. I'm going to give you the finger.



Still, I suppose it could've been worse; I could've been trying to sweep my willy. :O

LOL I guess I prefer the finger! :)

I see the sweep will work if using either one of the profiles, but not using both...
jonah

Yeah, the bug is that sweeps with more than one profile don't work, if the rails are sticking out past the profile instead of ending directly at the profile. Almost got a fix...

- Michael

Ok, both of these (Corzair's hull sweep and Wibble's finger) are fixed for the next beta release.

The bug involved multiple profiles when the rails were sticking out past the profile instead of ending directly at the profile.

Corzair, this bug is probably why you were running into general problems trying to sweep with more than one profile before.

Thanks both of you for posting the sample files, those make it a lot easier to track down what is happening.

- Michael