How to close a CV curve?

[john-d]

I need to draw a closed CV curve for lofting etc. What command joins and closes the 1st and last points on a curve, ala Illustrator's Join command?
Also, I've made some NURBS circles for use as tracing templates. Once they're set as templates, how can I set the circles so that they're more visible. I can barely see their outlines against the window's gray color? I looked all through the massive pref.s files to set a brighter color for template shapes to no avail.

[mistah_a]

you can use the C button on the keyboard and snap the CV to
the curve.if that what you mean??

[heydiddlediddle]

Did you try closing the curve?

and for the second question. If you can't find where to change template colors, did you try just changing the background color?

[john-d]

Thanks for responding. My question is: how do I close the curve? I want to know how to close the curve by connecting the first point with the last point. Is there a command in the Edit Curves menu that will "close" the curve? Or is there a mod. key that does so. Simply snapping the last point to the first doesn't appear to close the curve. Does this make sense?
My next thought for the template problem was to change the background color. Thanks.
John D.

[john-d]

Thanks for responding. I thought the "D" key was the snap to key. Oh well. I'll try the "C" key.
I'm doing one of the tutorials on the Maya AssistantOnline CD (How to build an iris) where it says: "Create a closed CV curve as shown". Then dupe it slightly higher in the Y co-ord, etc. The final loft operation is failing to produce a filled NURBS shape, and I realized I don't know if my initial curve shape is closed or not. I know this is a basic question, but even my prof. at NYU couldn't get the answer for me a year back, and the documentation is obscure on this point.
In Illustrator, for ex., using simple bezier curves, you can create an irregular shape and close it by clicking the final point of the curve over the first point; the resulting closed shape can now be filled with a color. I'm assuming a similar operation is required with CV curve drawing in Maya?

[heydiddlediddle]

I see what you mean now, and unless I'm overlooking something, there is no way to "automatically" close a curve like Illustrator's beziers. You would have to use the close curve tool, and fiddle with the options. Just keep in mind that NURBS curves act very differently than Beziers, and that depending on how you close that curve, the surface you derive from the curve will texturemap and deform differently. YOu can see if your curve is close in the attribute window. It will tell you under the shape node. It might say periodic, which is the same thing as a "closed" curve/surface. If you want that closed curve to have a "color" (i.e. surface) you need to "set planar" if the curves are all in one plane (i.e. no CV's are non planar with the others) or make a trimmed surface with the closed curve. Trimmed surfaces are better since they will not lose the surface if a CV is non-planar.

Sounds like you're prof. needs to brush up on some of Maya's basics...heheh.

[john-d]

Thanks! The Close Curve Tool? Is that the Open/Close Curves command under the Edit Curve menu? I wasn't having any luck with it's default settings on such a logical choice. I'll troll around the options for that command. THanks also for the NURBS warning; I've had a lot of people tell me about the many differences between bezier (familiar tool) and NURBS (unfamiliar tool), but not a whole lot of practical NURBs modeling tips in the manual for a newbie, eh?
 Question Two: What should be selected before running the Close Curve command? The first and last points?
 Yeah, my Maya class was when 1.0 came out, and there were a lot of simple things I know how to do in other 3D programs that I couldn't find out about in class. However, the prof.s strong point was animation and GUI customization, and I want(ed) to learn modeling.

[mistah_a]

hi i don

[heydiddlediddle]

Close curve only closes the curve using the already existing endpoints. If you need to attach two different curves, that would be the attach curve command/tool. If you can get your hands on a "NURBS modelling in Alias" book from the Alias Studio/Poweranimator manual set, it's a pretty good resource that is quite educational on how NURBS work. The books I've seen at technical bookstores go too far in depth unless you want to program graphics. A fairly simple (and very generalized) way of thinking about nurbs is curves that you draw the endpoints of the bezier rather than the point of the curve. Any techies will flame me on that overly simplifies generalization of NURBS, but it's a start. The first few pages of "Using Maya|NURBS Modelling" from the Maya manual set briefly describes NURBS, but I think the Alias Manuals are a much better resource.

Keep in mind that if you want sharp corners in a NURBS curve, 3 CVs will have to be in the same exact location for it to turn sharply, 3 CVs have to be in line for a line to be straight. That is unless you're using linear curves. And before you ask...a curve can not be linear and uniform ("curved"). You'd have to have either two seperate curves or line up and/or snap CVs to give that illusion.

If you're in a hurry to get something from Illustrator to Maya, try using Invigorator and importing as curves. It will automatically import beziers from Illustrator into Maya as NURBS curves. Works quite well too. Your school may or may not have installed it, Maya ships with a "light" version of the plug-in.

good luck.

[john-d]

Thanks for all the great help I've gotten here. I'm definitely gonna lurk around this BBS.
I should have thought of the Alias manuals for more NURBs info.
I understand what you mean in the NURBs/bezier analogy; I still think it's helpful. My TA at school was pretty clear about the differences between the two. I also have gotten the idea of the 3 points needed before the first point can be drawn, although I'm unclear about the 3rd or hull point and it's actual effect on the final curve; the 3 points needed for a straight line curve is straight ahead, so to speak.
I wanted to try working with the CV Curve tool before getting into Invigorator Lite and Illustrator. My TA at school took a dim view of importing EPS files, but never had time to fully explain real life NURBs drawing either.

[john-d]

I tried your suggestion of using the "C" key to snap the last CV to the first, but looking at the attribute editor for curveShape1, under nurbs curve history it says the shape is "Open" not "Closed" or "Periodic", so I guess I'm still missing something here.
I guess I'll just have to go with Invigorator and EPS since the documentation can't explain simple concepts such as this, in a way that I can easily find it. Using the online help yields too many hits, as much as I admire the search engine.

[mistah_a]

question;I have to ask you what shape you are modeling?
And are you gonna animate it?
because i dont close my curves when modeling simple shapes;

[lewis-h]

Shift + right-click the curve. A marking menu appears. Select Open/Close Curve.