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View Full Version : Rigging a cape or cloth object without Maya Cloth


lildragon
03-06-2004, 01:56 PM
Hi guys, been mulling over this one a bit. Have any of you tried to get a nice rig going for say a cape or loin cloth? I'm trying not having to deal with simulations and such, but I would like my cloth to fold in on itself and such to some extent of course. Maybe we can begin a discusion on this. Share techniques and ideas.

Take a quick look at this page to see where I'm thinking of heading

http://www.3dluvr.com/gato/stuff_superlopez_makingof_3_eng.htm

-lild

Morganism
03-06-2004, 03:44 PM
Hopefully this thread can help me out, too.

One of the characters I'm setting up right now has draping cloth, long hair, and a big dangling wing. I'm planning on using bones with spline IK to rig the cloth and such, I think it should work fine for these specific shots, because there's not a lot of movement. I don't know how hard it would be to handle if the character was moving around a lot.

Hmmm, now you've got me thinking about it.....getting complicated or realistic motion sounds like it would require a pretty dense rig. Maybe if you used just 3 simple bone chains (like superlopez) to get the basic shape and movement, and then clusters on top of that to tweak it. You could even throw in blend shapes on top of that to get really specific shapes.

Well, now I'm interested in seeing where this thread goes.

dmcgrath
03-06-2004, 08:38 PM
HA! I have been devising my own solution to this problem for a little while now.

I have made a batman (in my sig) that I used a very similar technique, I found that three joint chains is just enough to give good results but still be managable to animate. I'll post a little bit on the cape here in a few hours, when I have a good playblast worked out.

Basically I am using dynamics (softbody cape to be driven by the other one). And then SCIK in the three joint chains with controllers at the ends. It looks like it's working though!

Back in a bit.

muckywetnoodle
03-06-2004, 09:06 PM
I don't know how much control you want but LostPencil's tutorial (http://www.lostpencil.com/images/secondary.zip) I think is a pretty good springboard for ideas. It's easy to set up too.

I have to rig some clothing too and I am considering using a combination of dynamic rigging and joint driven blendshapes. I guess the difficult part is getting the cloth movement convincing.

lildragon
03-06-2004, 09:18 PM
Originally posted by muckywetnoodle
I don't know how much control you want but LostPencil's tutorial (http://www.lostpencil.com/images/secondary.zip) I think is a pretty good springboard for ideas.

This looks pretty promising actually, will have to test this out in some scenarios. The prob would be to get the fluidity that the cloth will need.

dmcgrath looking forward to seeing your solution so far.

BTW did anyone catch a glimpse at the new Blizzard behind the scenes sneak peak? THere's some great cloth dynamics in that.

Keep it coming gents.

salud

dmcgrath
03-07-2004, 01:57 AM
Okay I'll try and show you what I am doing, and where the heck my head is at.

1st - I did use the secondary.avi tutorial from lostpencil.com as a jumping off point for this. It has evolved into something else, I just didn't like the control aspect of it after I added two more.

http://spatiallight.net/challenge/bats/capeDetail01.jpg

This just shows the three joint chains I am using for the controls, including the actual "spherical" controls at the end of the chains that hold the IKs. These are hand animated and independent of the rest of the skeleton in the hierarchy.

----

http://spatiallight.net/challenge/bats/capeDetail02.jpg

The second image is both capes, seperated here to give you the details.
Esentially the upper cape is actually skinned to the joint chains, and then there is a duplicate cape that is softbody dynamics (almost just like the lostpencil tut.)
I pretty much just hide the upper cape and animate the IK controls the way I want them to. So far the results are very promising.

dmcgrath
03-07-2004, 02:05 AM
http://spatiallight.net/challenge/bats/capeDetail03.jpg

Here is the cape hidden, and then of course to see the result, you have to actually hit play for Maya to update its dynamics.




http://spatiallight.net/challenge/bats/capeDetail04.jpg
Ta - Da!



Here is a little animation
snip


850k .mov file (http://spatiallight.net/challenge/bats/bats_WalkCycle01.mov)

It is not polished up at all here. The shoulder area is causing a problem I haven't addressed yet. But the overall result is light and easy to maintain, as well as not too hard to setup.

Let me know if you need any more yappin`.

fortner
03-08-2004, 03:01 AM
did you guys see this thread?

http://www.cgtalk.com/showthread.php?threadid=125795

it's pretty much the same concept that you all are saying here, but it explains it a little better, and is more simplified.

kiaran
03-08-2004, 06:24 AM
This is a subject that I've been pretty interested in lately. I just love the dynamic secondary motion on the creatures in the Blizzard teaser. I would like to know what they are using to do that, but since they are primarily 3ds max, I'm guessing it's some sort of Reactor based dynamics.

Recently I came across the problem of rigging a character with a cape for an animated TV show. I was given the choice of using Syflex, but I ran into too many problems with it. I believe that with enough time I could've gotten it to work but when is there enough time, right? We ended up using a 3 join chain manual fk setup. Luckily the shots were quick, but the animators were still pretty pissed to have to do it all by hand.

This has led me to devote some of my free time to trying different ways of automating secondary motion like a cape. I decided to set out and try to get something like a ponytail. Here is a playblast of my progress so far:
Pony Tail Test AVI Divx 1.9mb (http://www.kiaran.net/tutorials/ponyTailTest.avi)

http://www.kiaran.net/tutorials/ponytail.jpg

This was accomplished using a method similar to the 'secondary' video. It's a splineIK on a chain of joints. Then the curve is made a soft body. But I DIDN'T make a goal object. Instead the pony tail maintains it's shape via springs that I manually created between each particle. Then I created springs attaching the topmost particle to the vertices of a poly cube. Add gravity to the soft body particle object. In this way, the dummy poly cube can be parented into the hierarchy of a character rig and the pony tail will flop around appropriatly. The trickest bit of setting this up was setting the spring attributes. After that it's a piece of cake to add collision objects by simply making any geometry a collider with the soft body particles (like the box in my playblast). Finally, you may find that the collision object intersects your skinned geometry because the particles are located in the center (not the edge where collision should occur). I got around this by making dummy collision geomety that is simply offset to make it look like the ponytail is colliding on the surface, not the center.

I'm currently researching ways to use rigid-bodies w/ contraints to control the secondary motion of things like the side-packs on the minotaur from the Blizzard teaser.

I hope this thread can help us all get better at one of the hardest parts of rigging. Keep the discussion going people!

caulfield
03-08-2004, 06:46 AM
I"ve found that a really useful and hardly used tool in rigging is the distance measuring thing. If you have two points, maybe the inner thighs, and set up a distance measure between them, you could drive blend shapes on the loing cloth based on how far apart the thighs are. You could then base another blendshape based on how high the legs are to the abdomen, and so on.

You'd probably be smart to add a couple of IK chains on top to add a bit of swing, but the distance tool can save you a lot of time.

I use it for wrinkling around the waste of my character waering a baggy shirt - he has one point on his chest, and one on his belt. When he bends forward, they get closer, and the shirt crumples (using a blend shape.) When he leans back, the front lifts up, exposing his stomach.

lildragon
03-09-2004, 12:14 AM
Ok this is what I came up with today, I think I'll need to take some pointers from kiaran on the collision with softbodies. Another problem I found out today during lunch, was that particles can't collide with one another, so the cloth tends to fold into itself at times :hmm:

As you'll see in the playblast I used a bit of both techniques, one with the secondary motion and the 3 bone hierarchy setup. It works great! BUT yes there's always a but, the collision objects have little to no effect when the "cloth" drapes over them. I also adding some springs

http://www.eyecandystudios.net/tmp/cloth_test.jpg

http://www.eyecandystudios.net/tmp/cloth_test.avi

keep the tips coming

-lild

kiaran
03-09-2004, 01:49 AM
I like what you've got there lildragon. I think using more than three joints in your chains would give the cloth a better resolution to bend with. My ponytail has 15 joints.

In order to help the collisions, remember that the only things that collide are the particles, so if you only have three particles in your chain, then only those three points will collide. As for interparticle collisions I'm afraid we're all hooped. I've heard of a work around involving a radial field attached to each particle so that they, in effect, repel each other. I've never personally set that up, but it should work, in theory.

I like that cape though, with a little time I think we could get this technique to a point where it might actually be usefull in a production environment.

YankyBJeans
03-11-2004, 07:16 PM
i have also seen the radial field setup on particles to fake interparticle collisions. It was on a gnomon dvd or a a|w dvd that I have I think. I can get it out and review it if youd like more info on how to set it up. I seem to remember that there was more to it than just setting up radial fields, but it looked to work really well.

Yanky

strarup
03-17-2004, 02:24 PM
Hi Lild,

I don't know if you can use it, but as I recall, Antony Ward used his AutoRig script to setup a cape for a superman character... -->
http://www.ant-online.co.uk/

here a little off topic thingie, but it could also be cool if somehow free cloth, could be implemented to Maya... -->
http://freecloth.enigmati.ca/

regards

Strarup

strarup
03-17-2004, 11:34 PM
Hi again,

maybe this Jiggle script can also help... -->
http://www.geocities.com/bazhutkin/jiggle1.html

it should e.g. work by having a head as a driver, and then the hair to follow it... maybe it could be used with 3 drivers aswell, e.g. the 2 shoulder joints and the neck/last upperback joint, and then have them driving some clusters on the bottom of the cape... and then also make the body somekind of collision object, so they won't go thru the body... :)

regards

Strarup

lildragon
03-18-2004, 01:28 AM
Wow strarup, these look like promising options, I'll give them both a go. Thx for that

-lild

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