Keyframing and Animating a Sack

[6pack1]

Hey everyone. I am in a 3D animation class, and I would like to know how to animate individual parts of a flour sack for the "Sack Drop" test/assignment. No matter what I try to do, I can't move individual parts of the sack to animate it without changing the sack throughout the whole animation.


I want to have it start sitting on a shelf, then at about 30 keyframes get hit by a ball, causing the sack to fall off the shelf and fall to the ground. If I can figure out the first individual movement, I can get the falling pretty well.

Anywho, thanks for your time!

~6pack1

[SheepFactory]

Did you rig the sack or was it already rigged?

Not quite sure if you are asking for animation or rigging advice. If its anim advice you are asking you should post a link to your animation so we can see it.

cheers,

-A

[6pack1]

No, it was created by scratch:

1) Got a Cube PolyMesh
2) Pinched the corner so it looked "Sacky"
3) Created a shelf/object for the sack to fall from
4) Created floor to fall on
5) Made all non-sack items Passive Rigid Bodies

Now, I am not sure if I should make the sack a soft body or Cloth body, or just animate it so it falls, but my problems changed as I learned new things:

At first, I wanted to animate the object itself (Get hit by a ball, have the top get folded and then the sack tumbles over) but whenever I changed the shape, it would change the shape from beginning to end. My question was at the time: How do I animate a fold or whatever else without changing the object throughout the whole animation?

Then, as I learned Rigid bodies, I thought, "Hey, maybe I could try that!" but now, if I make it a rigid bidy, it looks like it has Rigor Mortis (Hey a new pun for us 3D geeks, "Rigger Mortis") and just kinda bounces a little.

Now my problem is if I should go with Soft body, how should I do that, or Cloth, which would only work for the "Shell," and not the weight.

I don't have any video up yet, we still need to go through the Acme Animation sign-up process, then I will post my videos and link you to them. Hopefully my questions are open enough to just help with what would be the best method.

Thanks for your time,
~6pack1

-----------------------------
EDIT:

Ok, re-reading your post helped me in finding a new question to ask:

How would I go about rigging the Sack? Do I put "bones" on it? I doubt it, but would that help in animating it?

[Cryrid]

Now, I am not sure if I should make the sack a soft body or Cloth body, or just animate it so it falls
As it is for a 3D animation class, you might want to find out what concepts the animation is supposed to be teaching you. Because it is just a flour sack, there is a good possibility the goal was to animate it yourself instead of relying on simulation to do the work for you.

How would I go about rigging the Sack? Do I put "bones" on it? I doubt it, but would that help in animating it?
Yup, that's how it works. To rig it, you'd basically create the bones (A simple floursack would probably have 2-6 bones: 1 for each 'limb' if you treat the corners like hands and feet, and two for the body), and then envelope the Floursack mesh to these bones. That way when the bones move, the mesh will deform along with them(bones/controllers are a major help in 3d animation).

[6pack1]

Alright, I just need to know how to make those bones so they are only in the corners and middle (When I try to do them they start off in one spot and link to the next, effectivel making a circle of bones. How do you make it so the bones all point to the corner they control?

In other words, how do you make the bones point outward and link all together into the middle?

Anyone have any tutorial to do any of what I am asking? Pictures will help a lot.

[Cryrid]

Alright, I just need to know how to make those bones so they are only in the corners and middle (When I try to do them they start off in one spot and link to the next...
Right-clicking should end the chain of bones to allow you to begin a new chain/limb. There's bound to be a simple rigging tutorial somewhere. If I could find a opensource program that would let me record my desktop, I'd make a quick one.

[6pack1]

Right-clicking should end the chain of bones to allow you to begin a new chain/limb. There's bound to be a simple rigging tutorial somewhere. If I could find a opensource program that would let me record my desktop, I'd make a quick one.

Oh, alright. Thanks so much, I wouldn't have guessed that at all. Hopefully tomorrow when I am at the class I can get it all rigged and what not. After that it will just be the whole Enveloping thing and then animating it. Well, thanks for the support and tips. I hope to get as quick responses for every question.

Anywho, thanks for the help...I might be asking more, but hopefully I won't have to.

Sincerely,
~Brian, 6pack1

[6pack1]

Ok everyone who reads this, I have posted my animation/video on AcmeAnimation.org. Here is the link:

http://www.acmeanimation.org/Content/ViewFile.aspx?ArticleId=304926

Hopefully it links directly to it. If not, then search for my name (Same as here).

Oh, and also if you want to see the whole video, click the litle orange box at the bottom right of the screen, right next to the viewing box. It has a white "X" in it to magnify.