- [Instructor] Before linking objects together
in a parent child hierarchy,
there are a number of steps that we need to take
to ensure predictable results,
especially regarding rotations.
And if you skip these steps
then you may encounter some very difficult situations
such as getting to the point of animation
and then realizing that your entire rig is unsuitable.
It's actually really important that you follow these steps.
The first of them is to establish the position
and orientation of the pivot points
of all the objects that will be animated.
A pivot point is an anchor
around which an object transforms,
position, rotation and scale are calculated
relative to the objects pivot.
On the artist mannequin,
if I click on one of the objects,
such as the shoulder,
I'll see an access tripod indicating the location
and orientation of the object's pivot point.
And if I go to a transform tool such as move,
that'll make it a little bit easier to see.
The pivot point of the object is at the geometric center
of the object.
And if I try to rotate it,
and it's not going to rotate around the joint,
which is what I want.
Let's take a look at that.
I'll zoom in on that with the z key,
grab the rotate tool,
and try to rotate that,
and it certainly doesn't behave the way I want.
So I'll undo that with Ctrl + Z.
I want to move the pivot point
to the center of this ball joint, which is a spear.
To move or rotate the pivot point,
you need to go into pivot point transform mode,
and that's found in the hierarchy panel.
Go to the command panel and click on the hierarchy tab.
And then we want to go into adjust pivot rollout
and enable the button Affect Pivot Only.
Now we see that the pivot point itself is displayed.
It's shown as an additional access tripod
and I can orbit around with Alt and middle mouse,
examine that.
Let's move the pivot point.
We have the move tool and the move Gizmo is superimposed
over the pivot point.
For a precision, I want to move the pivot point
to the center of the sphere.
Let's make this easier to see
by isolating the selected object,
click on Isolate Selection, and then zoom in on the object.
In all of the view ports click on Zoom Extends All Selected.
We can snap to the points on this sphere
and we'll do that in 2.5D snap modes,
go up to the Snaps, click and hold on the button
and choose 2.5 D Snaps.
Also go into the Grid and Snap Settings,
right click on the icon.
And we only want to snap to vertex, disable everything
including Grid Points and enable Vertex.
While we're here, we can go into the options
and make sure that we have Enable Axis Constraints enabled
so we can close that dialogue.
To make it easier to see,
we can change the size of the transform gizmo
using the keyboard shortcuts
the equal sign on the alpha keyboard
or the hyphenated dash on the alpha keyboard.
I'll make that a little bit larger
so we can see that there's actually a circle here
on that gizmo, if I right click in the front view
and then move my mouse cursor near that circle
we'll see it light up in yellow.
That indicates we're actually snapping to that pivot point
and can just click on that circle and move the pivot point
up to the center of the sphere in that front view port
getting close with ctrl + alt + middle mouse
pan with middle mouse, just to make sure
that we actually have snapped to that center vertex.
We'll do the same in the top view
zoom in, dial in with ctrl + alt + middle mouse,
position that exactly in the center of that sphere.
Okay, now we've got that positioned where we want
we can turn off the snaps.
We can disable Effect Pivot Only
and disable Isolate Selection and test our work.
Switch back to the rotate tool.
And we can try rotating in this perspective view.
Right click in that view and click
and drag on the rotate gizmo.
And we see that it is now rotating around that ball joint.
Very good. I'll undo that with ctrl + Z.
However, the pivot point is not oriented correctly.
We can see that, especially in the front view.
And I'll back out a little bit again,
ctrl + alt and middle mouse.
The rotate gizmo will indicate the current orientation
of the pivot point.
If the rotate tool is in local reference coordinate mode
let's switch our reference coordinates over to local.
And now in fact
that rotate gizmo is aligned with the pivot point.
And we can see that the pivot point is not aligned
with the geometry of the object.
And we can try rotating that we can right click
in our perspective view and go back to rotating.
And it looks like we're only rotating
around the X axis in this case.
But in fact, we're actually rotating around two
or even three of the axis
that is not immediately obvious right now.
But we'll take a look at that
a little bit more deeply later.
I'll undo that with ctrl + Z.
We need to align the pivot point
with the geometry for best results.
We'll take a look at that in the next movie.
We'll rotate the pivot point into the correct orientation.