Cloth Controls Objects:

[entity]

This topic is also posted here:

 

http://www.hash.com/forums/index.php?s=&am...st&p=243770

 

Basicly, this technique is a way to have cloth deform a bulky object, just like it does with a button except using a bunch of bones instead of one.

 

Since cloth is made up of a flat mesh, you can add objects to the surface via path constraint to the cloth's splines, to allow the objects to stay with the cloth... well! This is done with constraints/bones, so why couldn't you do it also with bones in an object like a rope or a backpack (Woot).

 

:: You can create a cloth grid and set up as you would normal cloth on a character. Don't forget to make a deflector object for the cloth to react to.

 

:: Create some bones at each of the cp's of the cloth. Now you have a grid of bones (don't parent them... keep them all seperate).

 

:: Create a pose (ON/OFF) and start constraining those bones to the splines (path constraint). You will have to use "ease" to get the bones into the exact position on the spline, because the bones will attach to the spline at "0% ease" which is the begining of the spline. If you want to use 0% ease you must enter "0" into the "ease" field to create a keyframe in the pose, otherwise A:M will animate the ease automaticly in the chor from 0 to 100% over the span of time in the chor.

 

:: Now, you need to keep these bones handels pointing to the bone above in the grid, so use "aim roll at" to do that. Now, you got all these bones attached to the cloth when you turn on the pose in an action... wait... theres more!

 

:: You can create or import that belt or chain or backpack and rig it like your cloth grid (these bones need to be controlling the bulk object... only use the amount of bones you really need to make it work: the bones nearest the cloth will be the main bones. You can make other bones that are parented with these bones to control other parts of the object you made or imported.)

This object will not be a deflector... it is not cloth either so it doesn't need a simcloth material on it.

 

:: Make a new pose (ON/OFF). This pose will constrain your object bones to the closest cloth bones using "translate to" and "orient like".

 

MAKE SURE CORRESPONDING BONES ARE ORIENTED AND IN THE SAME POSITION!

 

That is a basic rigging rule... even if your not "orienting like", it's always a good idea to do it so your rig looks clean (it doesn't have to be perfect, just neat).

... Now you have all these object bones in the exact position and orientation of the cloth bones.

 

 

:: Hide (H) your object and simulate your cloth. This is just a test... doesn't need to be perfect or long lasting!

 

:: Un-hide your object and make sure your two poses are ON. Make the cloth transparent 100%, so it doesn't show, unless you want it to show.

 

Scrub through... Look at it!

There is an object distorting and bouncing around your character, something that can't be done as well with dynamic bones. If your object is sinking into your character... try setting your collision radius larger to keep the object from penetrating your character too much.

 

Hope you can understand this... I have a sample animation and project (There are some animations of the strap and chain examples here below, and two of the objects projects (Rope and Chain projects).)

 

I tried a rope object and a strap object and a chain object (the chain was created by Mike Muncy and is available on the A:M extras DVD)

FakeRopeDynamics_finalvback.mov

ClothControlsObject1.zip

FakeStrapDynamics_finalvback.mov

FakeChainDynamics_finalVback.mov

ClothControlsObject2.zip

[John Bigboote]

Entity-

 

Nice work! I'm pickin' up what you are putting down, man!

 

I had breezed thru that other thread where they discovered how to place a button on cloth, a quick read of yours and now I understand the technique fully! THIS is smart thinking.

 

If you raise the mass of your cloth OR increase the gravity force of the choreography you will get less jumping around...

 

GOOD BRAINSTORMING!

 

Myself...I have been 'toying' with the idea of using thin cloth strips as HAIR for a while now, might have to give it a whirl...

[Paul Forwood]

Interesting! That chain looks amazing except that it passes through itself. Did you have self collision detection turned on?

 

Nice work, Rich!

[NancyGormezano]

very very interesting - nice thinking (I have got to play with cloth one of these days)

[johnl3d]

Thanks for the info

 

Here is the info above in pdf form

 

 

cloth_bones.pdf

[Dhar]

Good experiments. I tried to simulate a rope/chain for Robert's "We're off we're gone" song, however, I couldn't control cloth enough to simulate a heavy chain. If you can make it so that it doesn't flip way over itself I could definitely use it

[entity]

Good experiments. I tried to simulate a rope/chain for Robert's "We're off we're gone" song, however, I couldn't control cloth enough to simulate a heavy chain. If you can make it so that it doesn't flip way over itself I could definitely use it

Only slowing down the deflector's movement worked to make it not flip so high... also what helps is changing the settings to 1/4 of the default settings in the cloth, but having the ball hit lower in the chain also works. DUDE... it's true physics at work here... if the character impacts it fast, that energy has to be causing a reaction like that! Accept the results of a fast moving object hitting a chain or rope... the only other way I can think of is to change gravity making it higher to keep the chains from being able to go so high... think "real" physics.

[entity]

Good experiments. I tried to simulate a rope/chain for Robert's "We're off we're gone" song, however, I couldn't control cloth enough to simulate a heavy chain. If you can make it so that it doesn't flip way over itself I could definitely use it

Here look at the settings and the speed of the ball:

FCD_mpeg_4c.mov

ClothControlsObject3_1.zip

[arkaos]

I notice in that movie, the chains bounce off of each other. I would expect the cloth geom would bounce off of each other, but it looks

like the objects constrained to the cloth also deflect off of each other. Is there a collision setting for the chain geometry as well?

 

That is a most impressive display of enginuity, there entity! Thanks a whole bunch for showing us how it's done.

 

Quick question: In your cloth grid rig, I see the bones pointing perpendicular to the grid. I see the large bone at top is to keep the

cloth from falling to the ground. What is the smaller bone below it for?

[entity]

I notice in that movie, the chains bounce off of each other. I would expect the cloth geom would bounce off of each other, but it looks like the objects constrained to the cloth also deflect off of each other. Is there a collision setting for the chain geometry as well?

No. The chain's bones are constrained (translate to) to the bones that are constrained (path) to the cloths splines.

That is a most impressive display of enginuity, there entity! Thanks a whole bunch for showing us how it's done.

 

Quick question: In your cloth grid rig, I see the bones pointing perpendicular to the grid. I see the large bone at top is to keep the cloth from falling to the ground. What is the smaller bone below it for?

Okay... the large bone at the top is the bone that holds the strip up, and the top spline cps is grouped to. The rest of the cps are grouped to the small bone which is the cloth's bone.

 

I constrained to each row spline a bone and each bone will point/ align itself in the positive direction of the spline, the base of the bone is at the start of the spline (0% ease). If you wanted you could "offset" it's position from the origin of 0% ease by translating it after the constraint is applied in the action or pose or chor... wherever you are animating it, and it would follow the paths curve and direction still, it would be off the path though... that is good for compensating for thickness. I suggest using ease to position the bone on the spline if you want it to sit in the middle or between cps.

The small bone you see highlighted in the screen capture is the chain link bone. I did that so you could see that the bone is "attached" to the cloth spline bone.

It is also interesting to note that you only have to build one set of chains but can instance it multiple times and still have the cloth simulate with the other cloth in the scene. So when you have many cloth objects in a scene, it will react to all the cloth you have in the scene if it comes in contact with it.

The cloth does the work and the chain is just following the cloth via the constrained bones constrained to the cloth's splines. The chains have no cloth on them... they are not in the simulation at all. Only the cloth strips and the ball are in simulation. The chains do rotate and bounce and stretch... that is the only real problem with it, but it's quick and relatively easy to set up.... you could do the chains better with Newton dynamics. I just want to show that you could change the geometry of the object without having to re-simulate again.

I will try something way more complex soon, so you can see what I really want to do with this.

Thanks for the replies!

[arkaos]

No. The chain's bones are constrained (translate to) to the bones that are constrained (path) to the cloths splines.

 

So it's just the cloth's collision radius keeping the chains from one model from colliding with the chain geom of the

neighboring model? That's more what my question was about. The rest I get.

 

I was playing with it, and using your simcloth method is definitely less expensive than using newton on the chain links. Thanks, bro.

[entity]

No. The chain's bones are constrained (translate to) to the bones that are constrained (path) to the cloths splines.

 

So it's just the cloth's collision radius keeping the chains from one model from colliding with the chain geom of the

neighboring model? That's more what my question was about. The rest I get.

...

Sorry, I tend to babble.

[Kelley]

Sorry, I tend to babble.

 

Babble on, Entity, babble on! This is so cool...!