Cloth

I would try and concentrate on just the loose parts of your clothing. When you wear a shirt, it's only the collar and maybe the ends of your sleeves that blow around in the wind. If you try and do the whole shirt, it's not going to look right. Concentrating only on the ends of clothing will give a nice subtle effect.

--Billy Eggington

The cloth control points will remain stationary until you right-click on the Spring System and select Simulate. The cloth control points do not automatically follow any skeletal animation that you do. If you are doing any animation of your character after you created the cloth, you must simulate. Or if you do any editing of the skeletal animation after you simulate, you must simulate again to update the cloth animation.

--Jay Mackey

You can find our tutorial about using cloth and forces on the Hash ftp site.
ftp://ftp.hash.com/pub/TUTORIALS/Flag/

-- Hash, Inc.

Yes, but I didn't use it on those shots (I decided, for time reasons, to go with thin geometry in this case). Thick geometry can be done by creating the spring system in a pose, selecting the inner layer and creating a cloth system, then attaching the outer layer to the same masses as the inner layer by hand. As you can imagine, it's pretty time consuming, but it does work. There's a better way, involving attaching bones to the springs, but I haven't had a chance to investigate it.

--Raf Anzovin

That's exactly what the Pixar folks discovered when they were R&Ding "Geri's Game". If the patches that his clothes were made out of weren't tailored just like real garments, then they wouldn't hang properly over his body when the simulation was run. We have found exactly the same thing with our cloth simulation. We always have our models in their rest (default) pose a predetermined number of frames before the first frame of action (for preroll), so the cloth has time to settle before the shot starts. If the rest pose of the model is really different from the pose on the first frame of action, then you have to give it more frames for the cloth to get into position.

-Hal Hickel

The Hash Cloth is very much the same. You have to "pre roll" to get it going. And to give distance/enough time for your cloth to calculate you want it away from the geometry. So like pants you would scale the legs down to zero percent and let them grow(longer or fatter) into the pants I have been using a string of "control points" as my "stitches". In other words just selecting the splinage to be simulated and not selecting the "stitches". Thus you can't fake the legs as just the pants. (hope that made sense).

Anyway, I am still experimenting.

-James "Dingo" Griggs

Increase the density(splinage) of your cloth. That will help. One simple way of doing that is to export the cloth as a quad dxf, and adjust the "polygons per patch" to 4 or 16. Then import that dxf. Thus you will have the same object with increased splinage/density. That will help with your cloth calculations.

Next, choose "Muscle Motion" then select the splineage you want cloth. Right click on that splineage and select the "Cloth Wizard". In the properties panel you will see the attributes of the cloth. On the "Cloth" tab increase your "Collision Radius" percentage. Try different percentages to see different results.

I have getting good results with a "Cloth/Collision Radius/80%", "Attributes/Collision Radius/0.5cm". This settings have created a cloth for me that behaves like "Silk".

-James "Dingo" Griggs

PS- the higher the collision radius the farther the cloth should be "away" from any intersecting models to give it time to simulate.

Something that I found that was very cool, although I have not really tested that much is to use cloth as water.

In my tests of cloth on Saturday, I discovered if you usea a low density plain you will have "pass thru" on your cloth. Now for cloth of course you do not want this. But for water it can give a "waking" effect.

I created a "bullet" model and attached it to a path. I created a flat plain of cloth and passed the bullet into it at an angle and it made waves. I have not tested this fully but looked pretty cool. I put the cloth pependicular and tried it and created and effect similar to the waving in the movie "Stargate".

-James "Dingo" Griggs

Just thought I'd share witht the list some of the info I've worked out on what setting that work for good results.

Under the attributes tab:
• Mass: .10 anything greater than this and the cloth starts drooping like toffee.
• I'm not sure of what anything else does on this Tab.

Cloth Tab:
• Stiffness: start at 1000 and up to 6000 seem to work good.
• Damping: not sure exactly what it does but relatively high values seem to work (40 -80) fairly well.
• Collision rad: %25 works if the cloth isnt going to be reacting to high velocity moves (ie. Bullets) higher values give the cloth more room to react but does have to be further away from the body at start.
• not sure what the rest of the stuff means anyone?

Anyone feel free to append to this thread and hopefully before you know it, we'll all have a good idea what we're doing.

Simon S. Jensen

Cloth Quick and Dirty:

• Mass is how heavy each cp is.
• Stiffness is how strongly the springs want to return to their resting length.
• Dampening is how much the springs resist stretching or compressing. (shock absorber)
• High stiffness to mass ratios are slow to calculate.
• Doubling the masses and stiffness will yield heavier cloth that stretches and bends similarly.

Cloth Tab:

• Structural items control the springs along the splines. These are what affects the look of the cloth most. (stretch/compress resistance)
• Shear items control the springs that diagonally cross patches. (tightness of the weave)
• Fold items control the springs that skip one cp along the splines. (starch)

Kevin Clark

These are my findings after I played with cloth for several hours. Hopefully some one will find this useful and experiment more while I go to bed.

1. To stop a cloth dropping dead to the ground, leave at least one row of CPs out off the cloth group. For example if you are making a dress, leave the belt area out of the cloth group.

2. Cloth definitely need time and space to settle before it can sense collision, so make other models well away from the cloth initially and move them back later while animating.

3. To dress a character, you have to dress it like real life, i.e.. you have to put hands through sleeves or fill the dress from inside with the body, otherwise the cloth will slide over the body.

4. Cloth effect cannot be seen real time, you have to simulate every time you do some changes.

5. The procedure I use to dress a model is as follows:

1. Make the character and the dress model, if they are in the same model, make sure the dress is assigned a different bone from the pelvis. The character should be in a "+" pose with hands extended for easy dressing.
2. In a cho. drop in the models, do what ever constraint if needed.
3. In skeletal mode scale the pelvis bone in the x-y(?) direction to 1%, this should shrink the character into a thin needle, leaving space for the cloth to settle.
4. If you are putting legs through pants, you better scale the leg bones in the z(?) axis too. This should shrink the legs to a dot.
5. Make the cloth group of the dress as cloth and do a simulation.
6. go to frame 15 for example and scale the pelvis bone of the character back to 100% and do another simulation, you should see the body fill the dress from inside.
7. If you are putting on pants, scale the legs afterwards. But remember to set key for the leg bones before go to other frames and scale. If not, the legs will scale together with with the pelvis and might push the pants from the inner-thighs rather then going through it.
8. After doing another simulation of the cloth, you are ready to do further animation. But remember to key all bone and muscles at the last frame so that futher animation won't affect the "pre-roll" beforehand. If you have a starting pose like standing with hands down, you can drop it in after this frame.

-Rijk Lau

OK, a quick "how to... cloth" This data came from many guys on IRC chat today.

Make your model, I made a sphere and a plane over the sphere, I named each group and boned each group. (Although, I don't know if that is needed, kinda too early to tell.) I did make the plane rather dense, like a 10 x 10 grid.

Create a new action, move the frame counter to 15 or so, grab the bone for the plane and translate it down over the sphere. Now change to muscle mode, select the plane's group name on the PWS and right click, selecting cloth wizard, type in these starter numbers. Mass = 0.05, Stiffness = 1000, Damping = 20, and Collision = 25%. (these numbers came from Will's text on the web)

Next, click on the model's name in the PWS, and then right click on "Spring System1" and choose, "Simulate." Save project and scroll through the action....

Yes this is a simple test... but it works.

-Jeff Cantin