Link objects / inherit pivot point of parent?


#1

Hi guys,

Is there a way of ‘linking’ objects (or groups) to other objects (or groups)?
Basically what I need is for a ‘child’ object/group to inherit the pivot point/axis of a ‘parent’ object/group.
3DSmax has had a superb feature for linking objects to each other for ages - this is what I am looking for.

Alternatively - is it possible to change the position and rotation of the gumball/pivot point?

Thanks!
Paul


#2

Hello,

I see what you’re talking about when you mention 3ds max linking system. Sadly I’m not enough skilled with Rhino to know something that could do this.

But I can answer to your second question about gumball pivot point. You just have to press Ctrl key before moving the gumball, then you can release Ctrl to move in any direction. You can set the gumball to use snapping or not or you can click on the gumball axis to set a value, or you may use the commande RelocateGumball to choose the origin then the orientation of x and y axis.

I hope it will help!


#3

@Cleps - CTRL is very, very handy - thank you for the tip!
I just tried it but it only seems to work for objects and block instances, not for groups.
Still - it’s a big step forward :slight_smile:

So…if there is a way to link block instances to each other…that would be perfect.


#4

Just to be sure you want links like parent/child where the child gets all the translation/rotation/scale of the parent but not in the the other way meaning that the child can also move on his own without moving the parent. (like in 3Ds)
Or a kind of link between two objects to make them move together but the pivot stays the pivot of the first object?


#5

Your first explanation is correct - the child gets all the translations of the parent but not the other way around.
So if I move the parent, the child moves along. Rotate the parent, the child follows the rotation. If I rotate the child however the parent’s state does not change.

Seems like a logical function to have in a 3D package…hope it is hidden somewhere in Rhino! :slight_smile:


#6

If you make a copy of the object with History on, it will behave that way - to a certain extent. It is based on the internal names of the objects (their “object ID”).

Limits are:

  1. if you modify the parent in some way that changes its object ID (like join it to something else) the parent child relation will be broken

  2. if you do anything to the child (like move it or change it in some
    way) the parent child relation will be broken

  3. Anything you do to change the ID of the object breaks the history

See the Help under History for more info…

–Mitch


#7

Hi Mitch - not sure how this should work - how do I make the link between the two objects?
For instance having a box and a sphere and I want to link the sphere to the box.

Thanks,
Paul


#8

Oh great…I just noticed that when you change the gumball state using CTRL, then save the file and then re-open it later the changed position of the gumball is gone and is reset to the default position.

Typical Rhino behavior BTW - you see the same happens when you apply UV coordinates, then save the file and then re-open it - if you now want to change previously assigned UV coordinates the seam-selection is gone and you have to start all over again. This apparently has something to do with information only being available during an active session and not being saved out…rendering the UV mapping function quite uselss IMHO. (I’ve never managed to get UV coordinates perfect the first time around not to mention the odd Rhino crash here-and-there :wink:


#9

No unfortunately, this does not work on disparate objects, only exact copies. Linking disparate objects so they move or rotate together does not exist in Rhino, except perhaps with one of the parametric plug-ins…
–Mitch


#10

Yeah, I guess it’s what Grasshopper is about. You should be able to make some hierarchy between objects to control their movements but that is definitively not as simple as in 3Ds. (which could be understandable as 3Ds Max is also an animation software where you need to control things like chain of bones, etc)

Good luck.


#11

Hi Mitch,

Thanks for the explanation … hope the McNeel guys have a solution for this.

Br,
Paul


#12

I found some info on setting of the pivot point and keeping the position - http://v5.rhino3d.com/forum/topics/permanently-moving-object-origin-gumball-position?page=1&commentId=6377196%3AComment%3A103241&x=1#6377196Comment103241

There is even a script that will store the pivot point / gumball position during saves! Only thing missing is that it doesn’t save an altered rotation of the pivot point / gumball.

I’ll have a look at Grasshopper in the mean while - thanks for the tip!


#13

Linking idea : use Bongo, http://bongo3d.ning.com/ an animation plug-in

Bongo 2 is in an advanced beta stage and is available for a free download. It’s designed for animation, but has all of the hierarchy / parent-child linking features you are looking for. Even better, it’s being written by McNeel (or a division?) so the compatibility should be high.


#14

Bongo 2 is awesome! Exactly what I meant - hierarchy, linking, parent-child…perfect, thanks! :slight_smile: