View Full Version : Gimbal Lock rotation problem

06-29-2005, 10:59 PM
Hi, how can I get the rotation handles looking a bit more useful for this character's legs?


PS any tips on how to avoid coming across this problem in the future would be great too.

06-29-2005, 11:35 PM
For now, imediately, you can look on the left hand side of your interface in the Modify tab and you'll find the coordinate system drop down. You can switch to world coordinates or to local and this will allow you to beat gimbal lock in a pinch.

Initially this problem starts - assuming you used skellegons - in modeler. When creating skellegons in the side viewports it rotates the bank of the bone 90 degrees.

Now there is a tool in modeler to rotate the bank but it is not very interactive and perdictable in my opinion.

There is another remedy.

To fix this simply deactivate your bones in the bones property pannel then take that hip bone and, looking at the rotation for bank zero it out.

Now, there is a trick to this because you will also wind up rotating all of the bones bellow it.

So before you start one thing you can do is clone the object - which will give you a reference to the initial bone positions. In the Scene editor make the clone object a bounding box to it won't conflict with the other object.

Also make yout initial object into a bounding box so you can see the bones good and clear - better than using bone xray.

Now if you really want to do it right color all of your cloned bones another color so you know what's what.

BTW if you have not checked it out look into the schematic view. If you set up this veiw in one of the viewports you can set up your bones in a tree for better editing and selection. Then simply move the cloneed tree overr and out of the weay and use the original object tree to do your selections.

Then you can start rotating from the hip down.

After you mess up all of the other bones beloiw it don't pannic, simply study what's going on. Rotate the next bone back into position using the cloned bones as a reference and the others will follow. You will have to go on down the line this way. You may have anckle bones out of wack too.

If you really study it you sill see that you can simpkly swap heading and pitch - I think it is - on the lower bone and be back in business.

Correcting bone rotations - in some way this method or another - is the first thing you shoould do after creating them.

Then two things left.

1) go though each bone and hit Shift P to record the rotation. This will set all the bones back to 0 starting point (even the ones that aren't gimbal locked)


2)Go through and select each bone and hit r. This will set the rest location and rotation of the bone and you are good to go.

Yes it is tedious no matter what method you use. This one is pretty darn workable.

06-29-2005, 11:55 PM
I would try the bone twist tool. In Parent Coord mode it works like the bank handles on skelegons - adjusting the handle on the parent effects the child.
Another way to do it is to go into Local Coord mode and use bone twist on THAT bone. Once you finish, change back to Parent Coord mode and hit shift + P.
I tend to avoid skelegons for rigging when using LW 8.x. Theyre easy to create but theres a few 'gotchas' to worry about. I find it much easier to rig in layout. Its pretty easy to draw bones in layout and do any adjustments there without the worries of drawing in the wrong viewport. :)

06-30-2005, 12:44 AM
Hi Surrealist and Splinegod, thanks for all the help!

Now if you really want to do it right color all of your cloned bones another color so you know what's what. Where do I change the bone color?

06-30-2005, 12:59 AM
In the scene editor

06-30-2005, 01:46 AM
Hey Larry. I saw your other post about bone twist and I messed with it but it did some very strange things to the rig. I posted a pretty extensive breakdown of what it was doing, I think in the post where you mentioned it.

Don't know if you saw that. I was thinking. Cool. I'd rather use this tool but it didn't work for me.

Where do I change the bone color?

Just left click on the item.

Also a pic of the scematic view. You can change colors/rename delete etc. there too just right click on the item. Drag the tiems around to arrange in a logical fashion as shown.

06-30-2005, 10:39 AM
Thats strange! I use the bone twist tool constantly as well as the others and they work fine. What were you doing specifically? :)

06-30-2005, 11:56 AM
I was just testing it out the way I do all things in the manual very well, more or less sceintifically so I can see if I understand it. I had loaded up the girraffe scene and was trying just to do simple things like turn the tool on and twist a bone, turn it off, etc. I narrowed it down to it messing up the rig by just turning it on and off. Now I was mindful of having the bones turned off but one of the things the tool did was turn them on. Subsequently the rig would deform badly.

Here's what I posted in the bug fix section.

Mid you I have been finding tons of stuff that does not work on my computer A few small examples: cycler, just doesn't work and sock monkey. Some parts don't work as they should some of these things are repeatable by others some aren't.

Here's my take on bone twist:

Ok Well I don't have time to grab pics on this one and give all of the details but... Bone twist is returning many unpredictable and undesireable results.

1) Load the Girraff scene from content/Scenes/Rigs

2) With the Giraffe object selected click on Bone twist

3) Hit space bar.

Nothing happens.


Now notice what happened.

If you play with enable IK enable deform and truning bones on and off without envoking the bone twist tool you will notice the configuration that Bone Twist defaults to when envoked:

IK Off
Bones On

You notice this by comparing the position of the legs of the Girraffe with the state it invokes under the tool to playing with these settings.

So if you know anything about bones you will know that you don't want to be twisting things around with bones active.

See what happens when you do.

Select bone twist and rotate a bone, hit the space bar.

Enable IK and bones.

Select a single bone, Enable Bone Twist tool for more fun results.

And it won't let you turn off the bones once with the tool is active.

Now this is under Joint Move and Tip Move which are both able to allow you to manipulate the bone and not affect the mesh (Within reason in so far as influednce is concerned). So I assume this in the purpose, though it did not say so in the manual and I have heard of this tool used as a fix for bone rotations and such which is usually due to creating skellegons and having their bank rotations at -/+ 90 rotation creating problems in animation.

The point is as far as I understand this is supposed to fix bone roations at the sub rest level.

I even tried hitting r after the fact, but that is- as one would expect - redundant because that is what this tool is supposed to do.

I also tried this in Bone Edit mode.

One thing I did check is that the bone I twisted did actualy rotate the bone below it. It states in the manual that this is NOT supposed to rotate the child bone.

Of course not. That is the point, right?

If so this tool simply does not work.