NURBS Loft Problem

[APE Design Ctr]

Hi all,

looking to make a ring, not unsimilar to an olympic trapeze ring.

Problem is, the profile is thin (.5" at the top, then thickens to 1" thick at the base of the ring. I made the circular .5" top rail, the 1" bottom rail, and the loft curve, and I get wonky results.

Any suggestions?

Thanks!

[Biplab]

Do you really need a loft for this? Or sweeping a trapezoid shape (0.5" at the top and 1" at the bottom) would suffice?

[APE Design Ctr]

The sweep is not a perfect arch. It needs to be an irregular sweep (like a teardrop).

Does this clarify things better, Biplap?

[islandmon]

Using 1/2 the Path & rotating the profile 90? before Extrude seems to work. Also the NURBS Curve and the Profile NURBS must originate from the same XYZ:

[APE Design Ctr]

Islandmon - are you doing a loft with this? Or are you doing a sweep?

Thanks alot guys,

Eddie

[alanmac]

Can you not do extrude along a path with a scaling factor to introduce the tapering from one thickness to the other for half the ring and then mirror and add solids ? Biplab explained how to for me on a tapering chair leg I wanted to do once, over on the VW list.

Alan

[islandmon]

Egg Profile to 1/2 Egg Path with Uniform scale = 3

[rdrines]

islandmon,

It is hard to not be impressed with the images you post. In the last image above the rendering seems more than I've been able to accomplish with Renderworks. Can you share what you are using for rendering in the example above?

Thanks for sharing the work and advice.

[islandmon]

Eddie,

The 'grey-out' happens when the Path is a NURBS Curve ( see OIP ) but NOT a Bezier Spline Curve ! Which is also called a NURBS Curve ... just to make things confusing. Therefore, you will need to use the 3D NURBS Curve Tool not the Create NURBS command. I just make the 2d curve then map the NURBS/Bezier to it.

One other thing:

If the Egg Profile = small on top large on bot, then the Profile needs to be rotated 90? in order to make the egg twist with the small part on the inside of the Path. Also, I try to always use the minimum Path .. in this case 1/2 of the egg, and then reflect , etc.

Roger,

The secret sauce uses at least 3 lights arrayed at least 45? and inclined 35.26? by default with Z = X or Y . Then set the textures to render as 'Phong'.

VW > Preference> Display > Black background.

Finally, I avoid working at large scales . All these example are created using < 100 centimeters which make rendering fast and the files small.

[APE Design Ctr]

I hear exactly what you guys are trying to do, and I tried that too. My options on Extrude Along Path are greyed out, and are only available when I the path to the profile (which is not my intended extrusion path). How are you guys making this work?

[APE Design Ctr]

Islandmon, thanks a mil!

[rdrines]

quote:

---

The secret sauce uses at least 3 lights arrayed at least 45? and inclined 35.26? by default with Z = X or Y . Then set the textures to render as 'Phong'.

VW > Preference> Display > Black background.

---

Thanks EJ,

VectorWork's Help file says "Phong" is a Reflectivity shader, but doesn't describe the word past its use. Sounds like it is time to do some trial and error work.

Thanks again,

[islandmon]

After review of the issues with the NURBS Path. I discovered that under certain circumstances a Path could be created normally by converting a 2D polyline into a NURBS Curve ( cut the egg shaped polygon in half >convert to lines >compose >convert to NURBS ) but sometimes not depending on various weird factors .

But in order to scale the Profile along the Path a NURBS bezier spline curve is required to provide the additional radial vertices needed for the scaling function.

[APE Design Ctr]

No worries, guys, finally got to what I want.

Thanks for all your help!

[islandmon]

While on the subject of NURBS Path peculiarities, I crashed VW during a simple OpenGL rendering. What worked fine a minute before took down the app. I traced the problem to a NURBS Path radius issue. basically, the NURBS Path Radius must not equal the Profile Radius at a 90? bend.

[APE Design Ctr]

OK, So with the different style of NURBS curve, I can get an extrude to taper, except it increases its width in the wrong direction. Any quick fix to reverse this?