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modo: mirror object and pivot

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rooster mod
hi, I have an object (lets say, a robot arm) which is on one side of a robot

I have the pivot point position set to the upper arm, and aligned with the arm (at a slight angle).

how do I mirror the whole thing across to the other side? so I end up with a mirrored arm and mirrored pivot?

it's driving me nuts :P. If I use the mirror function, the duplicate seems to go off at weird angles (it's as if the duplicate has been made, then the original pivot angle added back onto it)

thanks!

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  • rooster
  • Ben Apuna
    Sorry, I'm not very well versed with Modo's pivots/centers.

    Doing a simple two cylinder parent/child test with pivots placed at their ends. I was able to successfully mirror the hierarchy across the X axis in Item mode with positions and rotations intact using the "Mirror" tool. Though I had to re-parent the mirrored child cylinder to the mirrored parent for some strange reason it ended up as a child to the original parent cylinder after the mirror operation.

    If I moved any of the centers then bad things started to happen.

    Maybe this thread or this thread can be of better help to you.

    Good luck.

    EDIT:

    Here's another thread.
  • rooster
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    rooster mod
    hmm I can get an object to mirror across with pivot position intact if I freeze it's transforms, but the pivot rotation is not mirrored. it's the same as the original, which is rubbish :/

    in that second link, I'm not sure what he means in the second post: 'Playing with this more. In the animate tab I set the center of each item 'To Work Plane Position' (I had a few set to 'To work Plane Rotation').'

    what does that mean?

    cheers!

    edit:
    if I have a pivot position/rotation set and group the object, then scale the group by -100 then it appears to work, however if I unparent the object from the group the pivot screws up.. any ideas how to keep the pivot?
  • Ben Apuna
    Hmm... I'm not too sure what the guys in the links I posted are talking about. :poly136:

    Here's what I did earlier, which seems to work:

    modoMirrorHeirarchy.gif

    I also did this by scaling a group parent -100%. I think the key is to Freeze Deformation.

    modoMirrorHeirarchy2.gif

    Here's the lxo if you want to take a look at it, Modo 501(sp2).
  • rooster
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    rooster mod
    hi Ben, I'm feeling a bit dumb.. I wasnt able to recreate the animation steps properly I think..

    one thing is confusing me, when you talk about freezing: I didn't think you *could* freeze a group locator? the option is greyed out from the freeze dropdown and when I use the menu command like in the gif the scale remains -100. If you wouldn't mind could you write the steps from the 2nd gif in a list? really appreciate the help! thanks for taking the time to make the gifs too
  • Ben Apuna
    Yeah I know how you feel. Working at the Item level and animating things in Modo always makes me feel like I'm trying to draw with my feet.

    Anyway here's a breakdown of the steps for the parenting mirror:

    0. Make sure you are in Item Mode and not any of the other component modes like Vertices, Edges, etc...

    1. Right click the topmost mesh of your hierarchy in the Item List and choose and choose Parent to Group Locator.

    2. Right click the resulting Group Locator in the Item List choose Duplicate Hierarchy from the drop down menu.

    3. Change your Action Center to Auto (which should center it to the origin) or change it to Origin instead to be sure that the next step is centered on the origin. This step assumes that you intend to mirror across the origin.

    4. Make sure at this point that you are only selecting the Group Locator and not the child mesh nodes in the Item List. If you continue on and scale with everything selected then it will not have the correct result. This might be what has been causing you problems.

    5. Activate the Scale Tool. Make sure Negative Scale and Child Compensate are checked On.

    6. Input -100.0% in the X axis entry of the Scale tool. (or whatever axis you wish to mirror over).

    7. Drop the Scale Tool.

    At this point you're actually done. I just checked and there is no need to Freeze anything like I did with the animated GIF. I just assumed it was necessary from skimming one of the posts I linked to above :poly136:

    The rest is just cleanup:

    8. Expand the Group Locators in the Item List.

    9. Select the child mesh nodes under the Group Locators and drag them out from under them and back onto the Item List on their own.

    10. Delete the Group Locators.

    The following steps are to double check to make sure everything is oriented correctly:

    11. Change your Action Center to Local and your Action Axis to Local.

    12. Activate the Rotate Tool and select each mesh individually in the Item List to visually confirm with the Rotate Tool's widget that their orientations are correct.

    Hopefully that works for you :)

    I just remembered a much more complex method that I saw using Assembly Groups, maybe this could work.

    [ame]http://www.youtube.com/watch?v=7jmVyQQo8mg[/ame]

    It might be better to go with a full on rig for animation rather than simple parenting anyway. Though I haven't done any of this kind of rigging myself so I don't really know what I'm talking about at this point :poly136:
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