Copy/Paste for Components versus Copy/Paste for Bodies

[RogerInHawaii]

When you do a Copy/Paste of a Component the copied Component is implicitly linked back to the original Component, so that any changes to the Original automatically gets applied to the Copy. The copy is considered to be an "instance" of the original. If you want to get a copy of a Component so that it becomes a copy that is INDEPENDENT of the original then you do a Copy/PasteNEW.

But it SEEMS that when you do a Copy/Paste of a BODY  you don't get that implicit link back to the original, i.e. an instance of the original. Rather it appears that it becomes an independent Body, with no relation to the original. It seems like it's comparable to a Copy/PasteNEW.

Is that correct, or am I just confused?

[jeff_strater]

@RogerInHawaii - your understanding is absolutely correct.  I freely admit that this is confusing, and maybe even arbitrary.  The only thing I can say here is:  that's just the difference between bodies and components (or, one of the main differences).  Components support instancing, bodies do not.  You can get some of the behaviors of instancing with bodies, but it involves timeline gymnastics.  If you roll back before the copy body operation in the timeline, and make a change to the source body, it will show up in the copy.  But, if you make modifications after the copy/paste, those changes will affect only the body you modify (could be the source or the copy).  The instance model for components, though, makes it timeline-independent, sort of.  That is, if you put a hole through the body owned by a component, it will affect all instances of that component, even those created before the hole.  It's just a behavior you need to internalize and then it will just seem obvious...

[TrippyLighting]

Here is a 2 year old screen recording I made to explain the effects f copy pasting components and bodies in Direct Modeling and Timeline Mode

@jeff_strater I don't see anything arbitrary in that behavior. In fact when a users aware of this it can be used to great effect.

[RogerInHawaii]

The issue is one of inconsistent word usage and timeline affects.

In Fusion, Copy/Paste for a component means to create a linkage between the original component and the pasted one, with the pasted one being an instance of the original and not a part-for-part copy of the original.

But Copy/Paste for a Body means that there is no linkage to the original and there is indeed a part-for-part copy of the original. Which means that Copy/Paste for a Body is comparbale to a Copy/PasteNEW for a Component. For consistency it ought to be Copy/PasteNEW for what happens on Bodies.

Ages ago when simple text editors were becoming more fully powerful word processing programs the idea of Copy/Paste was developed. You highlighted some section of text and did a Copy, you selected a target location and did a Paste and the copied text was pasted into the target location. There was no linkage between the original and the pasted copy. This approach has become standard on all word processing, and many other, programs.

At some point someone came up with the idea of linking the pasted item with the original, and they called it Paste SPECIAL (or similar wording).

Fusion basically uses the established, original, idea of Copy/Paste for Bodies, in that you get an actual copy that is NOT linked to the original. But for Components it uses those same words, Copy/Paste, to mean a linked copy, comparable to Copy/Paste SPECIAL. If you do an operation X on a Component you reasonably expect that doing operation X on some other thing, like a Body, will have the same behavior. But Copy/Paste in Fusion does not.

There's also the issue of the use of the word NEW in a Copy/PasteNEW. When you do a File/New in just about any application what you get is a new EMPTY file. When you do a New Component operation in Fusion 360 you get a new, EMPTY, Component. The key here is that what you get from NEW-ing something is an EMPTY one of those things. Yet when you do a Copy/PasteNEW you don't get an empty thing but rather a thing filled up with a copy of the original. So it's not really a NEW type of operation.

I think that, ideally, Fusion should aim for some consistency in how it uses these words. Perhaps:

Copy/Paste to mean creating an object that is a complete copy of the original and having no subsequent linkage to the original.

Copy/PasteLINKED or mayber Copy/PasteINSTANCE to mean an instance of the original, linked back to the original.

There is also an inconsistency in how the various versions of Copy/Paste are represented in the timeline. Copy/Paste for a Component gets simply a Copy/Paste Feature in the timleine. Copy/PasteNEW for a component does NOT get any kind of Copy/Paste feature in the timeline but rather gets a copy of the entire set of Features from the original inserted into the timeline. But Copy/Paste of a Body, which is comparable to a CopyPaste/NEW doesn't get simply a copy of the original Body but rather gets a Copy/Paste feature. So in one case a Copy/Paste icon in the timeline means a linked instance and in another case it means a non-linked, independent copy.

There's no question that there are valuable uses for how Bodies are copy/pasted, but I think there needs to be consistency on what the words mean, not only to be consistent with how Copy/Paste is used in millions of other applications but also to be consistent simply WITHIN Fusion.

My recommendation would be to use Copy/Paste and Copy/PasteINSTANCE to distinguish the two types AND to allow both of those types to Bodies as well as Components.

[TrippyLighting]

When you copy paste a component you basically are just pointing to the original data.

When you copy a body there is no pointer, but in a way the link is the timeline, which the reason the copy paste feature is needed for a body.

If you want to make a change to both, the original and the copy/pasted body, then simply roll the timeline marker to before the copy/paste feature in the timeline and apply the change to the original. Then roll the timeline marker back to the previous position and you'll see the change now applies to both bodies. 

[jeff_strater]

@RogerInHawaii - I agree with you here, actually.  The terminology is confusing.  In fact, I don't think we should be using Copy/Paste as a UI for creating component instances at all.  Without trying to sound whiny, this is a discussion we had early on.  Some of us pushed for a separate "Create Component Instance" command for, well, creating component instances.  At the time, the idea was that we wanted to keep the number of commands in Fusion to a minimum.  So, it was decided to just overload Copy/Paste to do this.  The other related one is Move.  Fusion used to have separate Move and Move Component Instance commands, because those two operations are so different.  Moving a body creates a timeline feature, while moving a Component Instance puts you in Capture Position Pending state.  Etc.  But, again, the desire was for fewer, overloaded commands...  So, one Move command that does everything (including Sketch Move), and at least some level of confusion.  I do understand wanting to keep the number of commands to a minimum (have you seen Rhino??), but the confusion has a cost as well.

If only they would just let me make all the decisions...  🙂

[RogerInHawaii]

@jeff_strater I love your final sentence....

"If only they would just let me make all the decisions."

I feel that way about so many things. So much is screwed up in so many ways. And I don't mean Fusion 360, I mean politics and government and on and on, and so often I think to myself, "If only they had conferred with me, I've got the ANSWER!". 😀