View Full Version : How do I shape an object around a curve?

11-12-2007, 09:45 PM

In short, is there a way for me to take something as simple as a rectangle with a little width, height, and depth and shape it based on a curve?

My immediate need is to be able to model a scarf that I can shape around the neck of a character I put together, specifically and please hold the surprised gasps, a snowman. The skill has other uses, but that was what was pressing me now.

I had thought at one point I read about a way to shape an object around a curve, but for the life of me can't find or figure out how to do it.

I do not have anything modeled as of yet, but if this helps I can fudge something basic.

Any help is appreciated.

11-12-2007, 09:50 PM
there are a few plugins that let you bend things according to a curve in the background layer . Try www.flay.com .

I would do a scarf by using a rail extrude using a spline in the background layer .
You can then adjust the ends to suit.

11-12-2007, 09:56 PM
Thanks for the link and the advice.

I knew that there had to be something simple.

11-12-2007, 09:59 PM
A good way to do it would be to build the profile and use rail extrude (EDIT posted at same time) which works using a BG curve. You can make the curve with the Spline Draw tool and wrap it around the neck.

If you want to texture the scarf with a pattern, first select the profile poly and create a UV map. When you extrude it select "Make UVs" and this will draw out a straight UV map for texturing.

11-12-2007, 10:48 PM
C-Bend works very well.

11-13-2007, 06:01 AM
Here's another technique, if you need to animate the object flowing along your curve. (It's a bit complicated, and there's a bug in 9.3 that has to be worked around, but it's a great trick.) Let's call it a snake for the sake of this explanation, although this works really, really well for catheters going down vessels...

1. Model your snake straight, with the head of it at the origin and the tail out in the negative Z direction.

2. In a new layer, draw box the whole Z length of your snake. Add in some segments. The idea is to get points evenly spaced along the Z axis, the length of your snake. Kill the polys and delete any points you don't need.

3. Using Bezier, or Pen, or Sketch, create curve(s) starting at the origin and extending outward in the Z positive direction. This is the path you want your snake to follow. Don't be stingy with the points. It's necessary for smooth motion later to have lots and lots of points.

4. Select all those straight points as a curve, so that they're connected to the curve(s) and merge them all into one continuous curve. This will be the path your snake follows. (The straight ones in the beginning are for your snake's rest position. Probably not strictly necessary, but things get weird without them.)

5. Convert that curve into skelegons. Save the curve in a hidden layer, if you like. Copy the skelegons to the snake's layer.

6. Create an endomorph for that snake, so he's straight forward on the Z axis. Make sure he's far enough forward that he would follow the whole path you drew out. (Make sure you don't morph the skelegons forward. I have no idea what would happen if you did.)

7. In Layout, convert those skelegons into bones. Go into Scene Editor to select all the bones and set their rest rotations to zero. (I've had over a hundred bones in a single chain, each parented to the previous bone. Editing the rest rotations of each individually might just destroy your soul, so learn how to do them all at once in Scene Editor.)

8. Set bones to "Use Morphed Position."

9. Using Morph Mixer, advance that snake forwards to suit your taste. Animate the morph over time, and he'll snake forward over those bones.

I used this technique to model a necklace once. I used the points from the body to create a curve that followed the contours of the neck and shoulders, advanced my model over that curve, and froze it out as a transformed object.

11-13-2007, 12:55 PM
Here's a video (ftp://ftp.newtek.com/pub/LightWave/Tutorials/Vidz/property_web.mov) by Proton if you want to see it in action. BTW a great idea there to use save trans for a necklace.

11-13-2007, 11:27 PM
Even easier then the morph along a bone chain trick is to use DStorms free Trailer plugin or FIs Beizer bend tool or (if you can find it) Shift Spline Transform.

12-07-2007, 09:17 PM
Trailer works well but I can't seem to get it to work with bones. Does anyone know a better way to create a more complex motion with it? I need it to do 2 things:
1. Have forward motion of a long train along a curve
2. While the train moves forward, the path changes shape. (The last cars of the train will be on a different path from the first cars because the path is moving.)
Any suggestions appreciated. (I tried the morph mixer and bones, but it wasn't the greatest. Trailer is great for the forward motion.