What's the point of the first step of re-root tool?

[SaturnV]

You press 4 when you're not selecting/hold anything then it says: Select a set of two or more parts to attach

Tested a few, no luck finding any observable result by selecting different set of parts before selecting the new root part.

[The_Rocketeer]

The root part is the part you start with.

Lets say you start with part a, and add parts b, c and d, in that order.

If you select part b, it will detach taking parts c and d with it.

With the tool, you can change the root part to part c. Then when you select part b, it will detach with part a, and leave parts c and d together.

It's mainly useful for creating subassemblies, or changing how one subassembly can attach to other crafts depending on which part you set to be the root.

Edit: I might have misunderstood your question.

[King Arthur]

OP is asking why you need to select two parts to change your root part. Contrast SelectRoot which only asked you to select once which part would be the new root.

I'm actually curious about this myself, wondered how this worked when I tried out the VAB/SPH in 0.90 (I'm still on 0.25 ).

[GoSlash27]

It is as The_Rocketeer sez.

You have to select the first part so that it knows which part you want to be the new root.

You have to select the second part because the first part may have many parts attached to it and it needs to know which piece is the trunk.

Best,

-Slashy

[Anquietas314]

It is as The_Rocketeer sez.

You have to select the first part so that it knows which part you want to be the new root.

You have to select the second part because the first part may have many parts attached to it and it needs to know which piece is the trunk.

Best,

-Slashy

Actually I've found this is completely backwards; if you select a part adjacent to the one you want to be the new root, then the one you want to be the root, the new root is actually the second one you clicked, not the first. Of course if you click the same part twice that works too, which seems to suggest having to click multiple things is completely redundant. It's certainly possible for the game to rearrange the tree automatically based on selecting a single specific part as the root; the algorithm is a simple matter of applying various tree "rotations" to move the part upwards to the root.

[SaturnV]

Actually I've found this is completely backwards; if you select a part adjacent to the one you want to be the new root, then the one you want to be the root, the new root is actually the second one you clicked, not the first. Of course if you click the same part twice that works too, which seems to suggest having to click multiple things is completely redundant. It's certainly possible for the game to rearrange the tree automatically based on selecting a single specific part as the root; the algorithm is a simple matter of applying various tree "rotations" to move the part upwards to the root.

Thanks for your explanation, that's exactly what confused me.

[jeancallisti]

For the record :

http://forum.kerbalspaceprogram.com/threads/133527-Tutorial-how-to-use-the-root-part-tool?p=2180232#post2180232

[cantab]

I believe it was meant to let you reroot a set of ghosted out parts, for example that you just pulled off your rocket or another craft you merged in. But that doesn't work.

[Clipperride]

Thanks for the link too. I've completely rebuilt a couple of times because the Root tool confused me.

[Red Iron Crown]

I believe it was meant to let you reroot a set of ghosted out parts, for example that you just pulled off your rocket or another craft you merged in. But that doesn't work.

This. Apparently the idea was to be able to reroot detached subassemblies, but I haven't been able to make it work that way. The first click would still be somewhat redundant though.

[Starhawk]

This. Apparently the idea was to be able to reroot detached subassemblies

This was exactly my understanding.

The first click would allow the user to select either the ship under construction or a ghosted, detached assembly of parts.

Happy landings!

edit: Hopefully the UI rewrite will resolve this issue.

Edited September 6, 2015 by Starhawk

[MGM]

For what it's worth, I use the root tool constantly to manipulate ghosted sub assemblies. It's simple.

I might attach something axially below my rocket to set up symmetry on it, then pull it off to attach it radially. All you have to do is pick up the sub assembly, put it down, pick it up again and position your camera so the instant you click on the root tool button, your sub assembly gets placed somewhere reasonable that it isn't accidentally attached to your rocket. Then you pick the current root part of the subassembly - the part that makes the whole subassembly light up, then for step 2, you chose the part you want to attach the subassembly by.

I've been thinking about making a video demonstrating that. It's clearly buggy that it only works that way.

[CloudlessEchoes]

For what it's worth, I use the root tool constantly to manipulate ghosted sub assemblies. It's simple.

I might attach something axially below my rocket to set up symmetry on it, then pull it off to attach it radially. All you have to do is pick up the sub assembly, put it down, pick it up again and position your camera so the instant you click on the root tool button, your sub assembly gets placed somewhere reasonable that it isn't accidentally attached to your rocket. Then you pick the current root part of the subassembly - the part that makes the whole subassembly light up, then for step 2, you chose the part you want to attach the subassembly by.

I've been thinking about making a video demonstrating that. It's clearly buggy that it only works that way.

Thank you!!! This works, I've been so confused about this... saves so much time not having to remake subassemblies with various attach points!

[Alshain]

The first click is completely redundant and pointless. You can click any part you want, including the part you want to be the new root. Then click the new root part. However, if you click the new root in the first click you need to hover your mouse away from it before you can click again. It works if you click the same part twice.

[ibanix]

There is a nice mod that allows you to select root with one click: SelectRoot

[Sharpy]

The first click is to indicate the VESSEL you want to re-root.

You can re-root subassemblies before attaching them, or different vessels when merging.

If you have only one craft, the first click is entirely pointless.

[Val]

While that answer is correct @Sharpy, it's been more than a year, since the question was asked.