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Thread: Parenting of Bones between layers

  1. #1
    SciEngArtist PabloMack's Avatar
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    Question Parenting of Bones between layers

    I have a unique project that requires both hard and soft part animation. Hard part animation is done by putting each part in its own layer and moving the layers relative to each other. Soft part animation is done by using bones and weight maps requiring all parts to be in the same layer. In my project, a robot has to be assembled. Each module will be placed in its own layer. Each module is soft and will have its own rigging. But the modules must move relatively to each other and this should be done by moving layers relatively to each other. What I need is a way to move the base bone of a child layer relative to a bone of its parent layer. I want to avoid having to manually match the movement of a child layer relative to its parent bone. I also want to avoid having to have a soft model and a look alike hard model which will avoid having to do the work of keeping the two models in synch. Has anyone done this before?

    Special note: Robot assembly is part of the animation (hard). Robot operation is also part of the animation (soft).
    Last edited by PabloMack; 10-23-2012 at 01:52 PM.

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    Super Member nickdigital's Avatar
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    Why not put everything in one layer and rig the hard parts with bones?
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    Goes bump in the night RebelHill's Avatar
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    what he said... Im not sure Im getting what you're on about "a base bone of child layer relative to bone in parent layer"... exactly.
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    SciEngArtist PabloMack's Avatar
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    Quote Originally Posted by nickdigital View Post
    Why not put everything in one layer and rig the hard parts with bones?
    The modules have to be assembled together as part of the animation. Being in the same layer will not permit them to be separate parts. For example, the robot's head comes in a box. It is placed on the neck and chest which comes in another box. Each arm is in its own box and are connected to the trunk in their proper places. The legs are also placed on the trunk individually. All the pieces are assembled together in the animation. Then, once the robot is put together, it comes to life. Do you see the problem with what you are saying? If I did what you say, the "skin" will be stretched between parts as they lay in their separate boxes. This would totally destroy the effect I am aiming for.

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    SciEngArtist PabloMack's Avatar
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    Quote Originally Posted by RebelHill View Post
    what he said... Im not sure Im getting what you're on about "a base bone of child layer relative to bone in parent layer"... exactly.
    A bone rig is a tree (see "skelegon tree" under Setup/Skelegon Tree). (Do you follow me so far?) I am calling the "base bone" the parent of all the bones in the skelegon tree. If you have another layer with its own skelegon tree and you make the base bone (root of its bone tree) of the child layer the child of one of the "leaf bones" of the parent layer, then the child tree should act as an extension of the parent tree. Understand? You are basically extending the parent layer's skelegon tree with other skelegon trees from other layers. I don't think that LW can do this but, if it could, this would solve my problem. Of course, I talk about bones as though they are skelegons but you have to create skelegons before converting them into bones. I don't know why Newtek didn't just make skelegons ready to use bones but they did.

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    Unemployed Jester sandman300's Avatar
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    From what you describe, Parenter seems like an option for you. It even works on bones (even when a warning comes up that it won't). I would work the shot backwards, starting at the keyframe with the robot fully assembled (at the end) and work your way to the beginning. Use a different null for each part, you could even go without bones if you keep each part in a separate layer and set up the hierarchy like you would a skeleton.
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    Super Member nickdigital's Avatar
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    You could do what sandman300 says. Putting all the pieces is one layer is still possible though. You would have the skeleton for the body for the body animation control and then bones for the actual binding of the geometry to the rig.

    For example, there would be two bones for the head. One that stays parented to the neck (we'll call it "head rig" ) and then another head bone that's parented to head rig. We'll call that one "head bid". The head geometry is weighted to "head bind". You can now animate "head bind" away from and back to your rig.

    Without knowing what your animation needs to look like it's a little difficult to know how best to set it up.
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    Super Member nickdigital's Avatar
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    Quote Originally Posted by PabloMack View Post
    A bone rig is a tree (see "skelegon tree" under Setup/Skelegon Tree). (Do you follow me so far?) I am calling the "base bone" the parent of all the bones in the skelegon tree. If you have another layer with its own skelegon tree and you make the base bone (root of its bone tree) of the child layer the child of one of the "leaf bones" of the parent layer, then the child tree should act as an extension of the parent tree. Understand? You are basically extending the parent layer's skelegon tree with other skelegon trees from other layers. I don't think that LW can do this but, if it could, this would solve my problem. Of course, I talk about bones as though they are skelegons but you have to create skelegons before converting them into bones. I don't know why Newtek didn't just make skelegons ready to use bones but they did.
    If what I'm reading is right and you want one skeleton to control another you could constrain one to the other. That'd be a pain in the butt imho though.
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    Goes bump in the night RebelHill's Avatar
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    Quote Originally Posted by PabloMack View Post
    A bone rig is a tree (see "skelegon tree" under Setup/Skelegon Tree). (Do you follow me so far?) I am calling the "base bone" the parent of all the bones in the skelegon tree. If you have another layer with its own skelegon tree and you make the base bone (root of its bone tree) of the child layer the child of one of the "leaf bones" of the parent layer, then the child tree should act as an extension of the parent tree. Understand? You are basically extending the parent layer's skelegon tree with other skelegon trees from other layers. I don't think that LW can do this but, if it could, this would solve my problem. Of course, I talk about bones as though they are skelegons but you have to create skelegons before converting them into bones. I don't know why Newtek didn't just make skelegons ready to use bones but they did.
    Yeah... I know what bones are... I just dont understand your explanation of what you're trying to achieve. From what u wrote above, it sounds like you just want to parent the bones of one object to the bones of another... so great... parent them!

    Unless ur talking about dynamic/switchable parenting... in which case, use same as item to constrain the source bone from one item to the target in the other.
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    SciEngArtist PabloMack's Avatar
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    Quote Originally Posted by sandman300 View Post
    From what you describe, Parenter seems like an option for you. It even works on bones (even when a warning comes up that it won't). I would work the shot backwards, starting at the keyframe with the robot fully assembled (at the end) and work your way to the beginning. Use a different null for each part, you could even go without bones if you keep each part in a separate layer and set up the hierarchy like you would a skeleton.
    I did a test model and put each part in its own layer. Each part has its own bone tree. In Layout I select the layer, then, I press 'm' for movement properties. When I go to select the parent, all of the bones in the whole object show up. I've never noticed that before. So, apparently, using this method, you can parent a whole layer to a certain bone which can be in another layer. I am guessing that when you place the pivot point for a layer at the base of its root bone then the child layer's tree structure will behave as an extension to the bone tree that you are parenting it to. This, then, implicitly makes the root bone of that layer's bone tree follow the parent bone. So when you go to animate those joints that make motion between parts then you can either do it using layer pivot motion or bone joint motion. This is what I was looking for. Thanks.
    Last edited by PabloMack; 10-24-2012 at 04:56 PM.

  11. #11
    Goes bump in the night RebelHill's Avatar
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    Quote Originally Posted by PabloMack View Post
    apparently, using this method, you can parent a whole layer to a certain bone which can be in another layer.
    Of course. You can parent any "thing" to any other "thing". Save that is for if you try parenting an item to one of its own children.
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