- [Instructor] In this chapter on animation,
we'll first learn about setting up a transform hierarchy
or a network of links whereby we can pose,
or animate a character or any mechanical system.
In this example,
I've got a friendly artist mannequin already set up
with a hierarchy or a system of parent child links.
If I select an individual object such as this shoulder,
then if I transform it
the other body parts of the arm will follow.
I can go up to the rotate tool
and rotate that around some access.
And we see that the other two objects
in the arm follow automatically.
I'll undo that with control Z, there's a linkage
or a hierarchy among the objects in this scene.
And the shoulder object is a parent of the elbow object.
The elbow in turn is a child of the wrist object.
There are two basic rules about hierarchies.
The first, is that children inherit their transforms
from their parent.
The other rule is that a child can have only one parent.
First, let's talk about transform inheritance.
We just saw that with rotations, but of course position
and scale are also transforms.
If I choose the move tool,
select that shoulder object and move it,
we see that the elbow and wrist follow as well.
Undo that with control Z and scale is a transform also.
If I choose the scale tool and click on the pelvis
and scale it, all the body parts follow
because the pelvis is the ultimate root
of the entire hierarchy.
I'll undo that with control Z.
The other rule is that a child can have only one parent.
For example, this wrist has a single parent
which is the elbow.
That has a single parent, which is the shoulder.
And so on.
However, a parent can have many children.
As we saw, scaling the pelvis will affect all
of the parts of the hierarchy.
I'll undo that.
The pelvis has three direct children,
the chest, and these two hip objects,
and those objects in turn have their own children.
We can visualize the hierarchy in the scene Explorer.
Let's open that up.
I've got it currently hidden.
I'll make it visible from its button on the main toolbar.
Toggle scene Explorer.
We see that we've got a very simple scene here.
I've got a light and a ground plane
and the pelvis once again is the ultimate root
of the entire hierarchy.
And I know that it's got something subordinate to it
because it's got a right facing arrow here,
indicating there's something there.
We can click on that arrow and open that up.
And we see the immediate children of that pelvis.
If we want to see the entire hierarchy
then we can open up the whole hierarchy either
for the entire scene or just for this particular hierarchy.
We can open up or expand all hierarchies
from a command either in the scene explorers' display menu,
expand all or from the quad menu.
I can right click in the scene Explorer
and choose, expand all.
And that opens up all of the hierarchies in the scene.
Or I can go to right click and collapse all
and collapse all the hierarchies.
If I want to operate just on one hierarchy,
then I can use the control key, hold down control
and click on the arrow.
And that opens up the hierarchy for that particular object.
If I want to collapse it, once again control and click
and that'll collapse all
of the subordinate hierarchy members.
And I can see if I reopen this without the control key
we have indeed collapsed all of those subordinate members.
Okay.
Those are the basic concepts of a transform hierarchy.