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Thread: simple (?) targeting question...

  1. #1
    Cartoon-based life form mgrusin's Avatar
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    simple (?) targeting question...

    I'm targeting an object to a null, and restricting it to pitch. It works perfectly in this orientation:

    object ----> target +Z

    But I'd like it to work in this orientation (think radar dish tracking an aircraft: )

    +Y

    target
    ^
    |
    |
    object +Z

    But this only works on the +Z side of the object (when the target moves to the -Z side, the object rotates in the wrong direction).

    I can see that pitch-restricted targeting might only work for half a hemisphere, but that's fine - I only need half a hemisphere, I just need the overhead one.

    I've tried rotating the objects pivot to make it think that "Z" is "up", but I haven't been able to get that to work for me.

    I'm stuck, any help out there?

    Thanks! -MG.
    Last edited by mgrusin; 01-28-2010 at 08:52 PM. Reason: spelling

  2. #2
    Code Muppet evenflcw's Avatar
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    Doesn't sound like it shouldn't work, but targeting is quirky and seldom performs well with the goal traveling over zenith. Try setting the same thing up using a short IK chain instead.

  3. #3
    Cartoon-based life form mgrusin's Avatar
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    Thanks very much for your reply, I took your advice and solved it with an IK chain, but it took an interesting (to me) addition I hadn't anticipated.

    What I'm really trying to do is animate an equatorial telescope mount (the first link is elevation, and the second is a rotation of the telescope tube).

    When I did an IK chain through all the parts and set up the rotation restrictions, the chain did indeed point at the target, but chaining through the pivot of the tube meant the tube didn't need to rotate to satsify the IK. Hmm. I parented in an additional part at the mouth of the tube, which got the tube to rotate a little, but it was still only pointing vaguely towards the target...

    Then I realized I needed much more leverage to get the IK to honor the right angle in the equatorial mount. I parented a null to the boresight of the tube and put it a substantial distance away, then chained through the null to the target. Bingo! The target now needs to be further back, but the whole assembly now targets very nicely, including straight up, which is exactly what I wanted.

    Thanks again for the advice, I really appreciate it! -MG
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  4. #4
    Code Muppet evenflcw's Avatar
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    Glad it worked out.

    I still don't grasp how that thing is supposed to move. Mind uploading a short animation (now or later)?

  5. #5
    Almost newbie Cageman's Avatar
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    You can also try Relativity Motion Modifier and use its targeting function.

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