sweep command in VW2009

[DMorong]

In 2008 I could put a locus at the center point of a profile, like a baluster, and revolve the shape around its center. In 2009 I get an error "A sweep cannot be swept around a locus inside the bounds of the swept object" . Even if the locus in not inside the object but centered below you get this message. Now I know I can trim the profile on the center line and revolve it around its left edge, but this inability to revolve an object around its center does not make sense.

Mac 2.33 Intel Core 2 Duo

Os 10.5.6

VW 2009 SP2 build 99197

[Jonathan Pickup]

I can use the Locus inside the sweep, as long as it's not inside the bounds of the object

[DMorong]

It happens on 2 different computers, mine and a student of mine, both mac, both with the educational version installed.

I am in a quandary

David

Mac 2.33 Intel Core 2 Duo

Os 10.5.6

VW 2009 SP2 build 99197

[michaelk]

Can you post a file of the locus and object - presweep?

michaelk

[Pat Stanford]

The computational problem that is occuring is duplicate volumes.

Consider a Block letter C in reverse. If sweep it around the left edge, there is no overlap.

If you put a locus anywhere to the right, the areas show hatched will be covered twice while trying to do the sweep, one by the part to the right of the loci and once by the part to the left of the loci.

This is actually a benefit that it won't let you do this as many of the problems I fought with in VW2008 were due to geometry with double volumes. If you later try to add or subtract solids from them you get strange results and often crashes.

The error message is actually misleading. You can sweep things to the left of the locus, but only if they don't cause double volumes. Take a look at the last picture for an example of a shape that will sweep.

You just have to think carefully about the shapes you use to sweep.

[mike m oz]

DMorong, as Pat points out if you think about it logically there is a sound reason why the locus can't be contained within the horizontal extent of the sweep profile. The whole point of sweeping a profile is to create a virtual solid object having the required shape. Sweeping a half profile for an object like a baluster is a standard methodology in modelling programs.

[Stan Rostas]

Maybe is should automatically get rid of any geometry that overlaps upon itself?

[DMorong]

Of course you are all correct, Even if you sweep a symmetrical object on center you are wrapping it 180 degrees too many. (unless you limit the rotation to 180) I will quietly split my baluster profiles now that I get the reasoning

Thanks

David

[michaelk]

I've noticed some old pre 2009 sweeps behaving badly in 2009. Mostly rejecting their textures.

Has the sweep tool changed? ie. did it used to allow an object to be swept "inside the bounds of the swept object" and now it doesn't?

Or is something else going on?

michaelk

[Pat Stanford]

Yes, the new sweep is more sensitive than the old one.

With the old version, you could draw an object and sweep it 360 degrees around its center. While this looked correct, you actually ended up with a double solid as each half swept thought the same volume in space. This would often cause failures with later solids operations (adds, subtracts).

VW2009 will not let you create that kind of double solid.

I have not seen the texture problem, but it may well be releated.

[michaelk]

I think some of the "legacy" spotlight symbols might be affected.

Most, if not all, of the bodies are sweeps.

If you look at the Strand 6" Fresnelite, for example, something weird is going on. The sweep has the correct default instrument texture applied to it, but it clearly didn't "take". Wrong color, casts shadows.

I've tried to fix the sweep, but I couldn't figure it out. Replacing the sweep is the only solution I could figure out.

There's been a discussion about this on the theatre email list and this thread: http://techboard.vectorworks.net/ubbthreads/ubbthreads.php?ubb=showflat&Number=119790#Post119790

michaelk

[Pat Stanford]

I just checked the Strand 6" Fresnels light from VW2008.

I did not check how it renders, but I did notice that the profile for the sweep (edit the 3D part of the symbol and then double click on the body to get the profile) does extend past the sweep axis.

Try using the trim by line tool and cutting it back so that the "legs" of the profile stop exactly at the x=0 point in the edit mode and see if that makes a difference in the rendering.

[michaelk]

Pat

I tried the lazy way! I added a locus to the left of the profile.

No change.

michaelk

[islandmon]

Try moving the profile 0.00001 away from the axis... this usually does the trick in Sweeps & RevolveWithRail

[michaelk]

It just occurred to me why that might be a bad idea... Editing the sweep may behave differently from creating the sweep.

So I tried fixing the sweep the right way. It (the sweep) will not accept any texture or color - even after editing the "legs" of the profile to stop exactly at x = 0.

It doesn't seem to matter where the profile is in relation to the x=0 line inside the edit sweep space.

- Moving the legs to the positive side of x=0 just makes the resulting sweep smaller, not the same size with a hole, the way you would expect if you had used a locus.

- Moving the legs to the negative side of x=0 makes the resulting sweep bigger.

- Adding a locus at x=0 and moving the legs to the positive side of x=0 results in the same size sweep, as you would expect, with a hole in the middle.

- Adding a locus at x=0 and moving the legs to the negative side allows the double sweep!!!! No error message.

- Nothing I could think of would make it accept a texture.

I also created a new similar profile with an internal locus. It swept with no errors, but then wouldn't allow me to add or subtract a solid with it. But it would accept a texture.

Something happened to the original sweep that stopped it from accepting textures.

michaelk

[MullinRJ]

Is your profile open or closed? If open, try closing it. If closed, try opening it.

Raymond

[michaelk]

It was closed. Opening made no difference. At least in the crucial criteria of accepting a texture.

michaelk