Curves suck

[anakin78z]

Ok, I always go telling people how great houdini modeling is, but then I try the seemingly simplest tasks in the world, the sort of thing that any 3 year old using 3d studio max can do, and houdini friggin chokes. PLEASE someone tell me that I'm just fundamentally doing something wrong, so that I can get a job as a meter maid and get on with my life.

Here's my problem with curves. I'm trying something that should be a routine modeling task: draw a curve, draw another curve, sweep second curve onto first curve and skin. Sound simple? Well, I'd like to see you do it!

If you look at my Image, the backbone on the right is a circle sop, nurbs, and everything works as expected. The backbone on the left was a circle drawn by hand using the curves sop. After skinning, that's what it looks like. :shocking: :cry2:

-z

[Marc]

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... edit: Actually, don't worry. What you need to do is put down a resample SOP between your backbone and your sweep SOP.

You can set the resample down to as few points as you want, and it will skin correctly.

Another way is to insert a carve SOP down (no settings needed) between the sweep and the curve.

I believe it has something to do with the parameterization of the curve when you draw it. Admittedly I don't know the real reason, but my explanation has a big word in it, so you should just accept it as true.

[anakin78z]

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.hipnc

[Marc]

And something definitely has changed, it never used to screw up the sweep that much. I've done exactly what you're doing plenty of times and its always almost worked (ie, better results than what you're getting). Resampling the curve always produces better results anyway.

M

[Keyframe]

Heya Anakin,

You didn't close the backbone curve did you?

Closing the backbone curve appears to insert two sweeped circle at the last point on the curve. Not sure why, but I have a gut feeling that this is related to the knots that aren't visible. In order to maintain tangency, additional points at the end of the curve are snapped to the positions of the CVs at the begining of the curve. [anyone remember phantom keys from the old softimage days?].

It's also curious to note that closing the curve manually in the curve SOP, breaks the sweep, while inputing an open curve into a "primitive->close U" SOP makes sweep happy.

I blame the 80s.

Cheers,

Gene

[anakin78z]

It's also curious to note that closing the curve manually in the curve SOP, breaks the sweep, while inputing an open curve into a "primitive->close U" SOP makes sweep happy.

I blame the 80s.

Cheers,

Gene

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YES!!!! :notworthy: You totally made my day. The primitive sop trick totally worked. Why the curve sop doesn't do the same thing is beyond me, but be sure that I'll be bugging sidefx about it plenty .

Thanks again man.

Jens

[sibarrick]

Works fine for me. Slap down a curve sop, and a circle, close the curve and sweep the circle along it. Couldn't be simpler. Maybe you could describe the steps you took....

[Marc]

The trick is in how you close the curve, I believe. If you close it while drawing the curve, then things get all wacky.

M

[sibarrick]

The trick is in how you close the curve, I believe. If you close it while drawing the curve, then things get all wacky.

M

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Odd that's exactly want I did and it worked fine... see my last post.