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Thread: IK both ways

  1. #1

    IK both ways

    is it posible to setup ik chain to work like this:
    - simple bone rotated towards goal
    - when i move the goal, the bone rotates
    - when i rotate the bone, goal moves
    - i need it to work like this realtime (without making keyframes)
    ?
    next step is to make more bones to behave like classic chain, but the goal respects manual rotation of bones

  2. #2
    tricky tricky...
    Just curious, what is it you're trying to achieve with a setup like that?

  3. #3
    Ok, try this scene. The items that you should move/rotate are red and the ones that you don't need to touch are locked. I'm not sure how this setup would work in a chain. You're not rigging a snake by any chance?

    Edit: Also make sure the Coordinate system is set to "world" so it's easier to move the "Move_GOAL" null.
    Attached Files Attached Files

  4. #4
    oh.. so simple, why didnt i come with that by my self? thank you
    create the null, make it parent of the whole chain, and rotate it instead of bone..

    got inspired by this rig
    http://www.youtube.com/watch?v=k-xASD36X2M
    (ytb does not work for me right now)

    trying to do warious stuff with lw as seen on this video (maya)
    essentialy searching for something i cannot do..
    i even nailed 3 part piston
    thing(s) i found so far:
    - springy motion and other dynamic effects.. only way i can do it is with softbody / simulation / node item motion / point info node (dpont) => keyframing, no realtime feedback..

    why i want it realtime? - no reason, just playing and learning stuff

  5. #5

  6. #6
    found another problem
    trying to replicate this rig> http://vimeo.com/3564957

    how can i transfer local to world rotations?
    i mean:
    i got null A .. rotating in heading by parent rotation (propeller rotation)
    i got null B .. rotating in pitch and bank but not rotating with propeller
    i need to transfer rotations from B to A .. but after the heading rotation

    similar to base on helicopter head where transformations are transfered from static control ring to rotating control ring (see the rig on vimeo)

    any ideas?

  7. #7
    heh.. figured this out the moment i posted this question

    pitchbank the parent of rotation null (which rotates in heading)
    nevermind

  8. #8
    im rotating the parent with Rotation Item and controllers set to Same as Item
    Rotation Item set to "static" controler

  9. #9
    i got strange behaviour with ik
    if the object containing the bones with ik is unparented.. everything is OK
    but when i parent it (all objects with ik, goals, everything) under one master object (rot_no_an) the ik is behaving strange.. the final bone in chain with goal set is no more directly in position of goal, but only near, see the picture



    am i doing something wrong? the objects to which i am parenting is simple null at 0.0.0 with 0.0.0 rotation, no motion plugins, no ik, no expressions, no keyframes

    when i move objects back to "root" .. unparent them.. everything is back to normal
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  10. #10
    solved!
    i have to set "unafected by ik of descendants" for every propeller...
    stupid me

  11. #11
    finished helicopter head rig, uploading on vimeo, ill post it in few minutes

    whole object is easily updatable.. center is separated, propellers and their mechanical parts are cloned so you have to upgrade only one propeller model

    but there is no way to change angles / beam lengths.. without changing / updating the rig..

    im working on solution of this..
    bone has node item motion plugin applied with point info node and moved to position of inexed point.. so you move the point in modeler, save, and the rig updates
    this could be applied for any bone and goal null
    but i have strange problem with this.. x and z coordinates are switched.. so i had to switch them back manualy in nodes (vector scalar *3 into make vector)

  12. #12
    here you go
    http://vimeo.com/4338600

    forgot to mention bending of propellers, easily keyable with one null
    no sound

  13. #13
    Goes bump in the night RebelHill's Avatar
    Join Date
    Nov 2003
    Location
    jersey
    Posts
    5,766
    hey, nice rig...

    good stuff...
    LSR Surface and Rendering Tuts.
    RHiggit Rigging and Animation Tools
    RHA Animation Tutorials
    RHR Rigging Tutorials
    RHN Nodal Tutorials
    YT Vids Tuts for all

  14. #14
    Space Monkey 3DGFXStudios's Avatar
    Join Date
    Sep 2005
    Location
    Earth
    Posts
    3,121
    I didn't know a helicopter moved like that? Really nice rig!

  15. #15

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