WHAT is the deal with lofting??

# 1 09-03-2005 , 05:50 AM

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Hi... (waves)
I hope people are actually reading these, because it doesn't look like anyone has posted over here for a while... anyway...

WHAT is the problem with trying to loft two planar surfaces (that were originally filleted NURBS squares)? How do you keep the loft from turning out horribly twisted? PLEASE help, I'm really trying ot learn Maya so I can do something other than graphics for broadcast news...

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# 2 09-03-2005 , 05:59 AM

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Um... I don't think you loft surfaces, I believe thats a curve function. As for the twisting, check the loft options to see if auto reverse is on.

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# 3 09-03-2005 , 03:03 PM

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Yup or isopars, which means you can select a surface curve and loft that with normal curves.

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# 4 09-03-2005 , 08:56 PM

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Replies!

Thanks, y'all.

Well, that's what I would have thought, too (about lofting curves and isoparms rather than surfaces, I mean. I came to Maya from using 3DSMax, though not as extensively as I could've. Never really got to character animation, for example.) The lofting problem is coming directly from Learning Maya 6 and that jack--in-the-box project. Basically, the box's lid gets constructed from a curve that started as a square and was filleted and joined. Then, the curve is made planar and duplicated, and the edges of both the new planar curves are trimmed. The Trim Edges are selected, and those are the surfaces that are lofted (with, well, Surfaces-- Loft.) That's where the problem is consistently coming in with the loft being hopelessly twisted. I've tried rotating the original curve all over the place, which doesn't help much. Neither does Auto Reverse. All additional advice appreciated.

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# 5 09-03-2005 , 09:00 PM

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Okay, so you're starting with the trim edge selected... what are you lofting it with?

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# 6 10-03-2005 , 12:53 AM

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READ CAREFULLY FOLLOWING THE ***

I model in "Rhino" so Nurb modelling is practicall ALL I know about...

During a loft, you take one curve, then another, and create a surface between the two. A major problem is when you have surfaces which are NOT similar to each other (pentagon lofting with a square) -- it doesn't know which vertex drops where how when.

Though you seem to describe it as an exact copy of itself... in which case there are two possibilities:

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1) When "adjusting seem curves" -- make sure they are all pointing in the SAME DIRECTION. Rhino and Maya may be different, but when you loft -- it creates a curve joining the curves you "loft", and sweeps a surface along the curve it makes.... BUT in all honesty, if you have a square... how do you know where the start and endpoints are... it doesn't, so you need to adjust your "seem curves" accordingly.

To make an example of such...

If you have a wide ribbon coiled around two spools... the traditional way you'd imagine the ribbon to be (in the gap between spools), is in a rectangle shape... but what happens if you turn one of the spools around?

The ribbon in the middle gets twisted out of shape...

When all the "seem curves" are facing uniformly, its like the ribbon is not twisted... when the seem curves are facing oposite ways, its like the spool is twisted...

Mind you it visually will not LOOK like that, necessarily, when you render the glitch... but for troubleshooting purposes... that is an easy way to understand it.

Pros -- feel free to correct me... especially if this is 100% not accurate to Maya and is a Rhino-Only phenominon

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# 7 10-03-2005 , 12:55 AM

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Sorry for the double post --

the second possibility is that you make a nurbs curve (most likely just a straight line) between the two surfaces... and use whatever Maya's equivalent of the "Sweep 1 rail" command is. Its almost exactly the same as "loft" is.

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# 8 10-03-2005 , 01:32 AM

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I think the curves-of-the-square-not-pointing-in-the-right-direction thing was the problem. One nice thing is that if you mess around with something on a computer long enough, you can usually get it it to work, or at least work better than it did... whereas in actual space-time, that generally causes it to break. user added image

Learning Maya 6 really does have its problems as an instructional book, which I'm kind of starting to see because of this issue. But I've learned that if you ask enough people for advice, a lot of them will know something. (passes around Good Advice-Giver Karma.)

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# 9 10-03-2005 , 01:48 AM

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I highly recommend Maya 6 visual quickstart to accompany any project based book. Project books almost invariable miss a step or tell to perform a function without tell how or where to find it. The quickstart will allow you to look up tools and get brief description of how the work and how to use them.

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"If you love your job, you'll never work another day in your life."

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WHAT is the deal with lofting??

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