Is it possible to have two bones tied together so that when one bone is moved the other also moves?
Imagine a see-saw. When one side goes up the other side must go down. The two sides cannot be controlled by one bone because the pivot point is near the end of the bone. I need either to move the pivot point of the bone to it's center, or to somehow lock two bones together, one for the left half of the see-saw, and the other for the right half. But these two bones must move together as if they were one long bone with the pivot in the center.
Is this possible?
Thanks for any suggestions.
--gary
Newbie bone question: linking bones together?
Moderators: Víctor Paredes, Belgarath, slowtiger
There are two simple ways to do this:
1. Really easy version but requires parent/child relationship
Draw one bone with 180 degree rotation. With that bone still selected and holding the shift key click at the base of that bone and drag/draw a new bone. Now when you rotate the first bone (parent) it will rotate the second bone in the "opposite" direction just like a see-saw with the center point at the base.
2. Use a bone angle constraint.
This version might be better if you don't want the parent/child relationship with the bones.
You need to name one of the bones so it can be picked in the constraint dialog box. Draw two bones that are not parented to each other or another bone. One should be rotated 0 degrees, the other 180 degrees. Line them up so their bases are touching. Name one or both bones, doesn't matter but one must be named so it can be selected as a constraint target.
Select the bone to be constrained. Click on the Bone Constraints drop down. In the angle constraint drop down select the other bone.
You can't rotate the bone on frame 0 to test this out. You must test this on another frame other than 0.
-vern
1. Really easy version but requires parent/child relationship
Draw one bone with 180 degree rotation. With that bone still selected and holding the shift key click at the base of that bone and drag/draw a new bone. Now when you rotate the first bone (parent) it will rotate the second bone in the "opposite" direction just like a see-saw with the center point at the base.
2. Use a bone angle constraint.
This version might be better if you don't want the parent/child relationship with the bones.
You need to name one of the bones so it can be picked in the constraint dialog box. Draw two bones that are not parented to each other or another bone. One should be rotated 0 degrees, the other 180 degrees. Line them up so their bases are touching. Name one or both bones, doesn't matter but one must be named so it can be selected as a constraint target.
Select the bone to be constrained. Click on the Bone Constraints drop down. In the angle constraint drop down select the other bone.
You can't rotate the bone on frame 0 to test this out. You must test this on another frame other than 0.
-vern
Hmm...
Well the second version above works, just set the angle value to -1.
Be careful applying constraints to parent/child bone relationships. In the above "see saw" set up a parent constrained to a child or visa versa creates a "2 to 1" situation, like the spinning hands of a clock. Remember that a bone can't be rotated "by hand" if it is constrained.
The effects will be "cumulative". For instance if a child bone is constrained to a parent bones angle the child will rotate WITH the parent as well as the same amount ADDED to that amount. So when the parent rotates, the child rotates twice as much.
If a parent is constrained to a child bone, rotating the child rotates the parent... which rotates the child which is sort of the same as the other way. Rotating the child bone will rotate the parent... causing the child bone to rotate... again... twice as much. Same result.
It's kind of fun and strange to set up "weird" constraints like that. I don't know exactly when they might come in handy but it's nice to know they are there if I need them. Probably like spinning gears or machine works of some kind.
-vern
Well the second version above works, just set the angle value to -1.
Be careful applying constraints to parent/child bone relationships. In the above "see saw" set up a parent constrained to a child or visa versa creates a "2 to 1" situation, like the spinning hands of a clock. Remember that a bone can't be rotated "by hand" if it is constrained.
The effects will be "cumulative". For instance if a child bone is constrained to a parent bones angle the child will rotate WITH the parent as well as the same amount ADDED to that amount. So when the parent rotates, the child rotates twice as much.
If a parent is constrained to a child bone, rotating the child rotates the parent... which rotates the child which is sort of the same as the other way. Rotating the child bone will rotate the parent... causing the child bone to rotate... again... twice as much. Same result.
It's kind of fun and strange to set up "weird" constraints like that. I don't know exactly when they might come in handy but it's nice to know they are there if I need them. Probably like spinning gears or machine works of some kind.
-vern
By the way, if you use point binding you don't need 2 bones to create the "see-saw" effect. Just put the bone over the shape so its base is at the center of the shape. Bind the points to the one bone and now you have the see-saw action. It's pretty much what you would do for spinning wheels for a car or something similar.
Another thing to mention, the child bone (first simple version) doesn't have to be rotated the opposite direction of the parent. I only suggested that to simulate the idea of "bone" with two "ends".
-vern
Another thing to mention, the child bone (first simple version) doesn't have to be rotated the opposite direction of the parent. I only suggested that to simulate the idea of "bone" with two "ends".
-vern
If you leave out the "parented" part, it works. You need to name the bones which should control other bones later. See here:is it possible to create a bone that rotates a parented bone in the opposite direction? Like a bird front on...flapping it's wings?
This way you only animate the right wing and the left will follow. As you see the value of influence can be negative, which changes a movement's direction.
http://www.slowtiger.de/examples/bird.swf
Fixing the last child Bone
I am working on an animation - the profile of a motorcycle rider on a (jumping) motorcycle. The rider is in one bone layer and the motorcycle is on another.
Making the foot bone of the rider the master helps keep rider in contact with footrest of the motor cycle when adjusting the rider's position BUT how best to lock the riders hands to the handlebars (the last child-bone in a series from foot through leg torso and arm) when all I want to move is the legs, torso and upper arm.
I've tried what seems the obvious way, in the constraints menu (lock bone and position in relation to another bone), but can't find a way that stops movement of the rider hand (off the handlebars) when I move (say) the rider torso a little (with bone wiggle after frame 0) - even when the desired torso movement is not so great that the hand must move because the arm is straight and can't reach any more.
The rider and motorcycle are raster images being warped by bones. etc If anyone can help please ?
Making the foot bone of the rider the master helps keep rider in contact with footrest of the motor cycle when adjusting the rider's position BUT how best to lock the riders hands to the handlebars (the last child-bone in a series from foot through leg torso and arm) when all I want to move is the legs, torso and upper arm.
I've tried what seems the obvious way, in the constraints menu (lock bone and position in relation to another bone), but can't find a way that stops movement of the rider hand (off the handlebars) when I move (say) the rider torso a little (with bone wiggle after frame 0) - even when the desired torso movement is not so great that the hand must move because the arm is straight and can't reach any more.
The rider and motorcycle are raster images being warped by bones. etc If anyone can help please ?
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synthsin75
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Ha! I had a job last year with exactly the same problem. What I did was: I just separated the hands from the rest of the character and bound them to the handle bones. This way they moved with the bike even when I did vibrations.
It helped that the character was wearing big gloves so the arms fit nicely under the cuffs. I just had to adjust his arms so the wrist stayed where it belonged.
It helped that the character was wearing big gloves so the arms fit nicely under the cuffs. I just had to adjust his arms so the wrist stayed where it belonged.
