How can you tell if an object is an instance?

[Anonymous]

Pretty much what the title asks. I need to be able to distinguish an original object from an instanced one. No, I don't think layers it the solution here, as I would rather check the object itself as the source-of-truth.

[djonesuk]

I'd be interested in opinions on this matter but I'm not sure there is such thing as an 'original' or 'instance'.  They are just transform nodes with the same shape node attached.  As far as I can tell, only the name would give an indication of which was created first.  In fact, if you convert instances back into objects, it's possible for one of the non-original instance objects to get the construction history.

[mspeer]

Hi!

There is no difference between an instance and the original object, they have different transforms but they point to the same mesh/shape.

Therefore if you have 2 objects ( one is the original and one the copied instance) and you only want to keep 1 object it doesn't matter which one you delete. Also if you want to make changes to an object it doesn't matter which instance you choose.

[Anonymous]

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@mspeer wrote:

Also if you want to make changes to an object it doesn't matter which instance you choose.

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Hi mspeer,

Thank you for the reply! I think it may help if I clarify the question. How can I tell if an object is an instance, as opposed to a duplicate?

Let's say I add a cube to the scene and make a duplicate of it. I then also make another special duplicate (instance) of it. How do I tell by looking at the two new cubes' attributes, whether one is an instance or a duplicate? Especially in a scene with hundreds of objects.

In the outliner hierarchy, the original cube, the duplicate and the instance all look identical.

[mspeer · Accepted solution]

Hi!

Again, there is no difference except that instances share the same mesh, so just compare the name of the transform node with the name of the shape node.

Select the Shape (not the transform) and all instances will highlight in Viewport, or if all Instances share the same Material you could select by Material.

You may also check if a Shape is assigned to multiple transforms with MEL.

[djonesuk · Accepted solution]

You would have to use a MEL script to, for example, set the outliner colour.

$selection = `ls -sl`;
for ($object in $selection) {
    string $children[] = `listRelatives -fullPath -children $object`;
    string $parents[] = `listRelatives -fullPath -allParents $children[0]`;
    float $outlinerColorR = 0, $outlinerColorG = 1, $outlinerColorB = 0;
    
    if (size($parents) > 1) {
        //print($object + " is instance!\n");
        setAttr ($object + ".useOutlinerColor") 1;
        setAttr ($object + ".outlinerColor") $outlinerColorR $outlinerColorG $outlinerColorB;
    }
}

[absoluteKelvin]

very handy script djonesuk

[malcolm_341]

@djonesuk This is a great script, thanks for sharing.

[ayushbakshi98]

Hey, You can have this info displayed in the HUD of viewport by doing this. 

Menu Bar → Display → Heads Up Display → Object Details ✅

[malcolm_341]

@ayushbakshi98 Any idea what the Maya internal code is that queries if it's an instance or not for the HUD, or which Mel file I could find that info in?

[ayushbakshi98]

Yes,  A little bit.
Here's the mel command that, I think, tells the HUD if the selection is instance or not

objectDetailsInstance();

Some other python commands that might help to deal with instances:

https://help.autodesk.com/cloudhelp/2024/ENU/Maya-Tech-Docs/CommandsPython/filterInstances.html

https://help.autodesk.com/cloudhelp/2024/ENU/Maya-Tech-Docs/CommandsPython/instanceable.html

[malcolm_341]

@ayushbakshi98 Well, that solves it. Nice work, here's the code to test if the selected object is an instance.

string $instanceTrue = objectDetailsInstance();

if ($instanceTrue == "Yes")
{
	print "This is an instance\n";
}
else
{
	print "This is not an instance\n";
}

[MaYa_people]

This post seems old, but I think many people have this need. There are many instances of different objects in my scene. I need to get all the instanced objects by selecting one of them. My idea is to use the same shape nodes between instanced objects to reversely find their transformation nodes.