3d Spiral

[AndyM]

Hello,

I need to make a 3d model of a chandalier with spiral thingies on it. Everything is working fine until I make the spiral. I use the spiral tool, ungroup it, offset, fill in the ends, compose and extrude. It looks fine but everything gets REALLY SLOOOOOOOOOOOOW. It takes 5 - 10 seconds to even pan the screen. Anybody know why this is happening and if there is a workaround???? Many thanks!

[Guest]

You may want to set the 3d conversion resolution to a lower level to help speed up redraw times.

Go to File>PreferencesVW preferences and click on the 3d tab.

[Kevin]

You may be able to create your spirals with the "Sweep" command. Just draw your cross section, such as a circle and sweep it into a spiral. Don't know if this will speed things up.

[propstuff]

What's happening is that complex 3D objects make VW go REALLY SLOOOOOOOOOOW {:-(

You don't say what sort of machine you're on, but NURBS, Fillets, Sweeps,complex CSG objects, etc all make VW CRAWL on mine.

The way I get around it is to make the thingies and put them in the "finished thingies" Class. Then make a simple solid (eg cylinder) of the correct size to represent it -with perhaps 3D Loci on it if something else has to mate to it, and put it in the "Block thingies" Class.

Then by using Sheets, switch between having either one turned on. IE Work on the simple one and only turn the finished one on when necessary.

Also, using layers and classes to only activate various parts of a complex structure aids in this respect.

N.

[AndyM]

Hmmmm. I make complicated 3d stuff all the time but this is not that complicated. It is slow to the point of being completely unusable. I'll try and do a sweep or something else. I suspect that this has something to do with offsetting and composing a spiral in 2D because I now realize that it slows doen even before extruding. Many thanks.

My system:

P4 3.0 GHz

1.5 GB RAM

XP Pro

[AndyM]

Yup. As I suspected, the root of the problem is in 2d. If you can stand to wait long enough while your computer chews on it(I read a book) convert the extrude to 3d polys and it is fine. It makes about a jillion polys, but it works and looks fine. Is there a good way to reduce the poly count for just one object? I don't want to turn down the global setting.

Many thanks.

[propstuff]

quote:

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Originally posted by AndyM:

I suspect that this has something to do with offsetting and composing a spiral in 2D

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I don't really understand what you mean by this. but if you've got an alternative, hey............. :-)

quote:

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Is there a good way to reduce the poly count for just one object? I don't want to turn down the global setting.

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Turning down the conversion resolution is not supposed to effect the drawing accuracy, only the display. To do a finished output you turn it back up to high.

cheers

[AndyM]

Draw a spiral. Offset it. draw lines at the ends so it is closed then compose it. This is where it gets really slow and where the problem starts - in 2d.

[bc]

Hello AndyM,

I'm new at this 3D solids thing so please bear with me. I am trying to do a similar thing and I am asking for your help as I can't seem to find the help I need in the manuals. I am trying to draw an Italian light fixture that has a tapering spiral rod atop the globe. Imagine a spiral rod loosely wrapped around a cone. This is close to the shape I'm after. I can extrude a 1/8" circle along a planar spiral path but I don't know how to "lift" it. I would attach a graphic but have yet to figure that out as well....sorry. Can you or anyone else help me out?

[propstuff]

Andy,

now I understand....

When you said a spiral. I pictured a "barleysugar" twist, but you want a "mosquito coil".

Easy;

When you activate the spiral tool, click on the preferences in the mode bar, at the bottom is a setting for Thickness. Set that along with the others. No need for the Offset (which *does* create a bazillion verticies more's the pity) and compose business- it's already done.

When the spiral is drawn, Ungroup it. This will turn it into a Polyline, then extrude.

BC,

What you want is: Model> Create Helx Spiral.

Go to the Help in VW.

Towards the bottom of the front page is

Vectorworks Tutorials.

Go to

VW3D PowerPack Tutorials.

towards the bottom of the list is

Creating Helix Spiral objects.

cheers.

N

[ 05-29-2004, 06:24 PM: Message edited by: propstuff ]

[bc]

Hello again, I just now noticed the create helix spiral in the model menu, duh. I'll see where that takes me but would still appreciate any input someone might offer. I should say that it is geometry of the spiral that tapers and not the rod itself. Also I am looking to create a variable pitch such that as the spiral approaches it's apex the pitch reduces. Thanks thanks and more thanks, bc

[propstuff]

quote:

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Originally posted by bc:

I should say that it is geometry of the spiral that tapers and not the rod itself. Also I am looking to create a variable pitch such that as the spiral approaches it's apex the pitch reduces.

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The Tutorial shows how to make the spiral geometry reduce, but getting the pitch to reduce along with it: EEEK!

The Helix tool does not support this per-se.

The only ways I can think of to achieve this are:

Either make a number of spirals whose ends abutt, each with a slightly smaller pitch, and hope that no-one notices the "steps" in the pitch; a major fiddle. OR

Create the spiral with a loft of a number of Circle "profiles carefully arranged into the required 3D spiral; a major fiddle. OR

Create a Spiral NURBS curve with the required spiral, and extrude the required profile along it; still a fair amount of fiddle.

good luck

[bc]

Propstuff, Thanks for all the direction. I just may be able to "get there from here". I just happen to be the type that likes cutting their teeth on the tricky stuff....never mind the prerequisites. It's by the good graces and patience of folks like yourself that help us all learn. Thanks, bc

[AndyM]

quote:

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Originally posted by propstuff:

Andy,

When you activate the spiral tool, click on the preferences in the mode bar, at the bottom is a setting for Thickness.

N

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DOH!

[Peter van der Elst]

If you create a helix spiral and then use a circle to extrude along path (select helix). Then you can change the scale of the profile along the path (the helix). So you get a 3d spiral that starts with a "thick" profile and ends with a thinner/smaller profile. I don't know if this is what you're after?