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FK control crv: Parent constrain VS shape parent? (7 posts)

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  1. Sam

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    Posted 6 years ago
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    Hi there,

    In Jason Schleifers Animation Friendly Rigging Part 2 he shows how to create the FK control curves for the 2 spine joints. He uses a shape of a nurbsCurve with following mel command " parent -add -shape nurbsCircleShape1 torso_1_anim "
    It works fine. But what's the advantage of using this method instead of just using a nurbsCurve and parent constrain it to the torso_1_anim joint?

    I tried both methods on the same torso and couldn't either find a disadvantages nor advantages....

    Thanks you.

  2. Javier "Goosh" Solsona (admin)

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    Posted 6 years ago
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    You want to be able to select the curve and it'll select the joint.. not the other way around.
    The whole point of control curves is that you use them as your selectable control

    If that makes any sense

    J

  3. Sam

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    Posted 6 years ago
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    I don't get it

    But if i constrain the curve to a joint, I can select the curve and control the joint with it.
    Or am i misunderstanding something?

  4. greatbear

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    Posted 6 years ago
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    Using parent/orient/point (etc) constraints are heavier on the computer than simply adding the shape to the joint and can slow your rig down. The slower the rig is, the more frustrating/ less intuative it will be to use, which may compromise performance (and put the animator in a bad mood)

    Constraints are a necessity, but any little tips and tricks like this one that can avoid using them should be implemented to avoid this problem.

    Thats the only real advantage i'm aware of, if anyone knows of any others, i'd also be interested to hear them.

  5. Smapdi

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    Posted 6 years ago
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    I don't like that shape parent trick because it applies keys directly on the joints. One of the purposes of setting a control rig (usually nurbs curves) is to keep the animation abstracted from the joints. This let's you change the joints after animation is created (to a certain extent).

  6. Javier "Goosh" Solsona (admin)

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    Posted 6 years ago
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    I used to create empty nodes and then parent my own shape to them. That way I controlled the shape of my controller and it was not directly on the joint

  7. mzahmbie

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    Posted 6 years ago
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    Like others have said, you keep things a lot cleaner when you don't have to key the joints that drive your skin directly. It allows a lot more flexibility in being able to change the rig without effecting the animation. Though one thing I do find myself doing a lot is using joints as my control rig instead of transforms, and the control rig joints need curves so that the animators can select them to drive the bind skeleton so I use that parent shape trick all the time.

    The big reason I use joints in my control rig instead is because I want to be able to zero out my controls without using the freeze transform tool on a transform node. When you freeze transform anything that's not a joint it changes the identity matrix and the node because very confused on the concept of what 0,0,0 in world space really is.

    In most cases I don't think this is actually a problem, but it's caused me issues in the past so I now stick with joints as my control rig and parent shapes to the joints to give animators control.

    If you want to see what the change in the identity matrix does make a nurbs circle, move it, freeze transform, move it again and then run 'move -ws 0 0 0' from the script editor. You'll see the object doesn't go to 0 0 0 in world space, it returns to the point where it was frozen. This becomes a problem when you want to match the world space position of 2 nurbs curves(or any transforms) that have been frozen in different locations.

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