Is there a script for controling COG?

[kristine]

Is there a plugin or a mel script that controls the COG...for example, when the COG rotates, the whole body doesn't rotate with it, so it will be easy for me to make the "Contra Posta" pose. Because I already animate a run cycle, and I need to adjust and give more rotations to the COG.. but then if I do that.. I have to adjust many upper body rotations as well? Anyone knows? Please help.. Thanks in advance..

[gnimmel]

By COG (center of gravity) i'm guessing you mean the root or hips of your character? If so, I don't think you can do it know without altering the spine to counter what you do to the hips.
To get arround this in the future, you need to add to your spine set up a way to do this, the simple way being add a extra joint for the hip rotations below the main root node so you can rotate the hips without the spine rotating.

Thanks,

Richard

[mattcioffi]

Hey Kristine.

it may be hard to re-rig your current character, but in the future if you where to have your root bone(top most in the hierarchy) just not be either the pelvis or waist bone you'll be golden. becuase - when you go to rotate the pelvis its' below the root and the waist is on a different branch of the hierarchy entirely. writing this really fast -hope it makes sense and is usefull

cheers
mattCioffi

[kristine]

So you guys would suggest the root of the bone to be the bone above the waist or pelvis for example and not be the pelvis bone.... and make the pelvis bone a separate bone in a different hierarchy...Is that right?

So right now, there's not really any script that can solve this situation, right? Because I already have some animations on it...

Please reply, thanks

[gmask]

If I understand the problem correctly I think you could make a new root node and then parent whatever one you are currently using to it. Then move the aniamtion channels from the one you were using to the new root.

[kristine]

Thanks for replying gmask, but I don't really understand what you mean by making a new root node and the rest... do you mind to explain it more in detail... like where I go about in Maya to accomplishing this?

Thanks..

[gmask]

I'm still trying to understnad the layout of your skeleton.. a picture would help.

Assuming that currently your COG is the hip node.. the problem is that when you turn the COG/hip/Root the whole body turns... right?

What you need to have is an additional joint above the hip and above the waist or first spinal joint.

The other problem is that you have allready keyframed the hip and first spinal / waist joint and need to preserve that motion.. is that correct?

[gmask]

LEt's assume that you went about keyframing your character so that the hip was the root.

You now want a new root.. so that you can rotate the hips wihtout the whole body to move.

If you unparent the next joint that goes up the body and put a new joint in there and parent the hips and the waist to it then you'll have created a new root but the animation in the upper body will be off.

To fix this you actually put two new joints in there between the hips/COG and waist.

Parent the hips to the one that is the Root and then the waist to the other new joint we'll call offset.

Then copy and paste the rotation channels off the the hips and onto the offset joint.

The functions used were Joint tool, parent/unparent command and copy/paste.

BTW the two new joint should be in the same place as the hip joint. It may help to use the hypergraph when doing the parented and copy/paste functions so you can click on the right ones.

Is this for a game ..

[kristine]

Gmask, thanks again for your reply.. it seems you've got a good idea how to deal with my problem.

Let me show you a picture of my skeleton setup.
http://www.geocities.com/kamie888/Skeleton1.jpg

So in your reply, it said that I put 2 new joints between the COG and the waist spine. Do you mean I draw 2 long skeletons (like those long triangle size) , or just use the Joint Tool to "just click once and press Enter" to put only a "circle(with a cross in the middle) " on there?
So these 2 joints should exactly be the same place as the COG joint, right?

If you have time, do you mind to simply show on a picture how you would set it up, and how the skeleton hierarchy would look like? Sorry for all these troubles. I guess I got a bit confused on your explanation...

The other problem I had is that I already have animations on all the joints already... so after if I added the 2 new joints... I would lose the animations, how would I go around this and still keep the animations. After adding the 2 new joints, do I need to adjust any weighting to the model?

No, this is not for a game.. it's my own demo reel.

Once again, thanks for your help.. Hope to hear from you soon.

[kristine]

Sorry again.. I just want to inform you that you can't directly click on the link above.. You have to copy and paste the URL to the address bar in order to work..

[gmask]

I think that you can do this without changing the weighting if you have allready bound a skin. This is only because you are actually adding joints rather than subtracting them.

Select the waist joint and unparent.

With the joint tool click once.. and name it Root
Then select the Joint tool and click again create one joint and name it Offset.
So you have two "spheres" rather than a full bone if you will..

Parent waist to offset
Parent COG to Root
Parent Offset to Root
Copy Channels from Root to Offset

[kristine]

Gmask, thanks for your detail explanation of the process on how about in setting it up.. It works perfectly.. You are my savior.. Thanks sooo much...

But after I modify the skeleton setup... the animations all got screwed up... I guess I will just have to copy those digits of the previous rotations and the translations of those bones to the new ones....

By the way, I was wondering what do you mean by "Copy channels from Root to Offset?" I don't get that.. What do you mean when you said "Copy Channels?"

Once again, I appreciate for your time and help.. You are just amazing.. ^^

[kristine]

Gmask... I have a big problem after doing all those steps you've suggested...

After when everything seems to go well.. I tried to go to move any joint.. and go to "Bind Pose" .... Everything seems to be twisted , model and skeleton wise.. and doesn't go to the bind pose..
Also it showed error messages saying,

Warning: Transformations were applied to Root to restore the global bindPose on Spine since its parent has changed since the pose was saved. //
// Warning: Transformations were applied to Root to restore the global bindPose on Waist_Spine since its parent has changed since the pose was saved. //

Before I do the setup... I've deleted every animation keys on it.... I don't know why it has that problem.. any ideas?

Please reply soon.. Thanks..^^

[kristine]

Let me explain what I did again, I move any of the joint.. and after that I went to "Modify>Enable Node> Disable All" , since I have IK on the arms and legs.. Then I went to "Go to Bind Pose" Then the waist spine got translated up therefore stretching the body... When I go Enable all again, the legs got twisted...... It's soo weird..

But it seems to be alright if I don't ever "Go to Bind Pose"..... Before, I usually saved a key on a frame of the bind pose... that's why I always need to Disable all and then be able to go to the bind pose... .
Hm... what do you suggest this time? I would really love if going to bind pose would work....

Hope to hear from you soon.. Thanks

[gmask]

Sorry I didn't mention the various pitafalls of doing this.. it's really a last resort. It is allways better to start over especially if you have a binds..

I'll post more later..

[gmask]

By the way, I was wondering what do you mean by "Copy channels from Root to Offset?" I don't get that.. What do you mean when you said "Copy Channels?"

Actually I think I mean tto say copy the rotations from the COG/hip to the offset..

In the channel window you can sleect channels there and withthe right mouse button copy them and then pick another object and select it's channels and past over them.

[gmask]

After when everything seems to go well.. I tried to go to move any joint.. and go to "Bind Pose" .... Everything seems to be twisted , model and skeleton wise.. and doesn't go to the bind pose..

Well since the skeleton is modified the old bindpose will no longer work... It's not really too much of an issue though.. that is if you set a keyframe for the skeleton in the bindpose which I personally prefer.

Here's soem other threads on the subject
Deleting the Bindpose
Reseting the Bindpose

[kristine]

Gmask,

I've finally got everything worked out ... along with the Bind Pose problem... After I deleted the old bind pose and saved the new one.. everything worked out great.. and finally, I've copied all the animation over to the new improved skeleton setup... Boy, without your help, I don't think I could solve this problem... Thanks for all your help and your time... You are really nice... I saw you have your ICQ number posted on your info, do you mind if I add you to my list? I'm sure I will really learn alot from you... Thanks.. ^^

[gmask]

No problem .. I'm glad it worked out for you... As a matter of fact somebody else just posted a similiar problem.

Yeah I haven't used ICQ in awhile.. I spend plenty of time here though