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What is a 'Root Node' (Read 847 times)
Reply #15 - Apr 14th, 2009 at 5:42am

Wing Nut   Offline
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I think what's confusing me is this:

First, how do you do the process of creating a dummy part?

and

What is the difference between have a plane (or triangle) as a dummy part and having the actual fuselage as one?  No matter how many polys they have, or how big they are (Horton Hears a Polygon?) a part is just a part...

Kevin
 

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Reply #16 - Apr 14th, 2009 at 1:09pm

Fr. Bill   Offline
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Wing Nut wrote on Apr 13th, 2009 at 7:12pm:
So I actually name the part 'Dummy' then?  I did that the named the fuselage 'exterior' and the cockpit tub (wich is at the top of that hierarchy) as 'interior'


No. As Felix stated, you name the dummy object whatever you need it to be, such as exterior or interior, or any other name that you might wish to use for organizational purposes.

The major reason for creating and using a "root node" though is that...

...every object Linked to that node inherits the x,y,z properties of that node...

In effect, the root node acts an an anchor for the entire project.

In theory, you could reverse the direction of a "backwards flying airplane" by simply rotating the y axis of the root node 180º using the Gizmo while the root node is selected.
 

Bill
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Reply #17 - Apr 15th, 2009 at 8:59am

Felix/FFDS   Offline
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A dummy part is merely an anchor, like Fr. Bill says.

Think of it as the tab divider in a school kid's binder - you don't want a "regular"  page to be the divider between subjects.
 

Felix/FFDS...
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Reply #18 - Apr 15th, 2009 at 9:10am

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Is this what we're talking about?  It's not the concept that's throwing me here, it's the methodology... Smiley

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Reply #19 - Apr 15th, 2009 at 1:59pm

Fr. Bill   Offline
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Yep! That's the "Dummy" object...

...however (I can hear you groaning!), I tend to avoid using them for the most part because...

...in an FS9 compiled model, animations are stripped out of the export stream if any have been applied to a true "Dummy" object.

Rather than run the risk of such occurring, it is my practice to use only a pseudo-dummy object that I create myself.

That pseudo-dummy object being a single, tiny, square polygon who's face is downward, so it won't ever be seen.
 

Bill
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Reply #20 - Apr 15th, 2009 at 2:06pm

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So what makes that more suitable to be a dummy than the fuselage?  Undecided
 

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Reply #21 - Apr 15th, 2009 at 2:28pm

Fr. Bill   Offline
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Wing Nut wrote on Apr 15th, 2009 at 2:06pm:
So what makes that more suitable to be a dummy than the fuselage?  Undecided


One word: consistency!

As I've stated previously, the entire model "inherits" the properties of the "root node."

One critical property is the precise location of the "root node's" axis, which must be the scene's centerpoint (0,0,0).  Another critical property is the orientation of the object's axis in the scene's world space; i.e. which "directions" the x, y and z axes point

Think of the "root node" as if it were the keystone of an arch.

All other stones in an arch must have a precise spatial relationship with the "keystone" otherwise the arch cannot be self-supporting; it will collapse as soon as the scaffolding is removed.

In a similar fashion, if you move the "root node" in the scene, every object Linked to it will move in precise formation...

If you rotate the "root node's" axes with the Gizmo and "Affect Pivot Only" selected, you simultaneously affect the pivot point orientation of every object Linked to the "root node."

These two concepts are why I choose to use a very simple object for my "root node(s)" because it's far easier to visualize the centerpoint of a single square polygon (two equilateral triangles) than it is a complex set of polygons such as a fuselage.

Remember always that it is the pivot point of an object that's the important and crucial determiner, not the object itself!
 

Bill
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Reply #22 - Apr 15th, 2009 at 2:33pm

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...

I think...   Cool


You know, I consider myself a reasonably intelligent guy...
 

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Reply #23 - Apr 16th, 2009 at 12:05pm

Fr. Bill   Offline
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Remember that I used the emphatic word "must" regarding the x,y,z origin of the root node's axis...

There are some who might quibble and say that this "ain't true 'cause I don't do that and I see the a/c in the sim..."

However, those who might say that don't understand that the sim assumes that the model's origin point in 3d space is 0,0,0 and the entire flight design envelope (FDE) is predicated on this being true.

All points in the FDE (flight controls, lights, et cetera) are relative to the relationship of the model's origin (centerpoint) with the sim's world space.  If this spatial relationship is not in 1:1 correspondence, then all manner of weird and unpredictable things are likely to occur...  Shocked
 

Bill
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...
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