Rotation flipping

[shuggypudd]

Its a newby question:

Any ideas why my skeleton flips 90 degrees whenever I constrain orient. I have never really been able to understand the joint rotations on my skeleton rigs.

[mantrid]

When joints flip during animation, it is because of something called gimble-lock. see http://www.anticz.com/eularqua.htm

Anyways, in your case, you have chose to aim-constrain. You need to adjust your aim-constrain vectors to have it point the right way. i.e. you have an up vector and an aim vector. Adjust those accordingly to get it to aim correctly. Try changing 1 0 0 to 0 1 0.

Anyways, you should be using pole-vector constraints to solve joint flipping, not aim constraints.

[bumpsetspike]

When setting up an orient constraint your slave object will be rotated to match the orientation of your master object. In order to see what the orientation of the two objects are you can look at the local rotation axis. This is in the component menu under the icon "?" (the one that looks like a question mark). Often times when you wish to orient a skeleton to a vehicle or prop, the local rotation axis is different because you will often be constraining a root node of a spine where X is the up axis. Your vehicle (or whatever is the master) will often have Y as the up axis. This will cause the 90 degree flip. One way to solve this is to have an intermediate node (a locator or a null node) which is oriented to the skeleton and then a child of the master node.
Here is the workflow.
1. make a locator name it "con_loc"
2. orient constrain "con_loc" to the skeleton (skeleton is the master and "con_loc" is the slave)
3. delete this new constarint
4. you might want to repeat this with a point constraint if you are doing a point constraint also.
5. Make "con_loc" a child of your master node (vehicle, prop, pogo stick, whatever)
6. now set up the orient / point constraints with the skeleton as the slave and the "con_loc" as the master.

no flipping

alan

[shuggypudd]

I'll have to repeat both of these till I comprhend whats going on. But what I ended up doing was creating a locator moving it to the joint. Orient constraining the joint to the locator to reset it position. THen I deleted the locator and froze the joint to reset it all to 0. then fixed the next joint in the hierarchy. {cause it got tweaked}. Basically redoing the skeleton positions.