All language subtitles for 07_12_drivers_basics

- [Zack] Before adding the face controls

to our character rig,

let's learn about the basics
of drivers in this video.

So later on,

we will use two bones to fully control

the face of our character rig.

However, let's have a look at
the basics of drivers first

to better understand what we are doing.

In general,

drivers allow us to control
values using other values

or scripted expressions.

In this video here,

we don't go into a scripted expressions.

This would go too far,

and in general, I'm not
an expert in this field.

However, there's a link
to the documentation

of the drivers down below
in the video description

if you wanna learn more.

Here we just wanna do
some very basic drivers,

but these will probably
cover most all the things

you will do with drivers anyway.

So, and as you can see,

I set up a very simple scene here

where we wanna apply drivers.

So here we have two handles,
the red one and the green one.

And with the red one later on,

I wanna control the
intensity of the lamp here,

and with the green one,

I wanna change the position of the lamp.

So basically first,

we move this out with a green handle here,

and then we turn on the
light with a red handle.

Before we get started,

let's have a quick look at the scene here.

First of all,

you maybe noticed that I disabled

the selection for some
of these objects here,

basically for all the
objects which we don't move

or change at all in this tutorial,

so that we can't accidentally select this.

Then both handles, this
one here and this one here,

are parented to the cube things down here,

and over here, the lamp,

which is a point lamp is
parented to this object,

and this object here is parented

to the cube thing down here.

Then for the lamp object
here in the object settings,

under viewport Display,
I enabled in front,

so we can see the lamp better

and to make the selection
and so on easier.

And later on with the red handle,

we don't just wanna control
the intensity of the light,

we also wanna control the intensity

of the emission shader,

which I added to this
lamp object over here.

You can see I increased the emission,

we can also increase it to 10 here

to make it a bit more intense.

So, and before we get into drivers,

let's actually add some
constraints here to the two handles

so we can only move or rotate
the object in a certain range.

So we learned about constraints before,

that means let's do it quite quickly here.

Let's go to the constraints.

Let's press N to open up the sidebar,

and under Item, we can see the Transform.

In this object I wanna move
positive 0.08 and negative 0.08.

So let's add a limit location constraint,

and this along the y-axis.

So X and Z, let's limit to zero,

and let's change the
Owner to a Local Space

so it will stay here

and not go back to the
center of the scene,

which will happen when we
have World Space enabled.

And then for the Y minimum,

let's set this to a negative
0.08 and positive 0.08.

And now if I press G,

I can only move this in
this certain direction.

And let's even limit the
rotation with Local Space

and set everything to zero here,

so I can't rotate this thing at all.

So we can only move this
in this specific area.

Then for this handle,

it's a bit longer because
I wanna rotate this.

And you can see here
we have the X rotation

of 30 degrees and negative 30 degrees.

So again, let's add limit
rotation constraint,

local space, here Z and Y should be zero,

and we wanna rotate
this around the x-axis.

So Y, Z zero and limit X

should be at negative 30 for the minimum

and 30 for the maximum.

Now, when I press R,

you can see we can only rotate
this in this certain area.

And same as before, let's
also add a limit location.

With everything enabled,
everything at zero and local space,

now when I press G I
can't move this at all.

Here for this object,

we won't set up any constraints

because we don't wanna
touch this object at all.

This should be fully controlled
with these two handles here.

So how to add drivers.

A driver you will always add to the value

which you wanna control.

So let's start with this object here.

Let's go to the material settings,

make sure the light material is selected.

And here I wanna control
the emission value.

So that means I wanna move
the red handle along Y,

and this should turn the
emission from zero up to 10.

So first we need to try

what should be the maximum value here,

and I think 10 should do the job.

Then when you wanna edit driver,

simply right click on the
value and click on Add Driver.

Then this menu here pops up.

We will get back to this in a second.

However, if I move my mouse
away, it will disappear.

But no worries,

all you need to do is
right-click on this value again,

and click on Edit Driver.

Then this pops up again.

Also, you noticed the value turns purple.

That means this is now
controlled by a driver.

We can also see this curved arrow here,

which also shows us that we have a driver

controlling this here.

That means I can really change
this value manually anymore.

Then if you wanna remove a drivers,

simply right on here and
click on Delete Driver.

So, now let's remember,

I wanna move this along Y
on a maximum value of 0.08.

So let's reset the position here.

Right click Add Driver.

And as driver type, we don't
use the scripted expression.

We could enter a script down here

if we know what we are doing,

but we don't do.

So let's change this to the average value,

which allows us to control this value here

using another value which is
the Y location, for example,

of the red handle.

So for all we do, just switch
this to averaged value.

Then we have an arrow here

because we haven't defined
a target object yet.

And of course, one thing I'm
doing completely wrong here,

I have currently the handle selected.

So let's remove the driver here.

Of course, I wanna have the lamp selected

with a light material.

And here, I wanna add that driver.

So of course, add this
to have the right value.

So average value, then as target object,

I wanna have the handle
light, which is the red one,

which is controlling the light.

And we wanna change the Y location.

You can also see we can
use a rotation or scale

to control this value,

but here I wanna have the Y location,

and we wanna have the local space

because this object here
is not at the center

it's somewhere here outside,

and it's parented to another object.

So that's why we are using local space.

Then let's get back to Edit Driver.

And this is all we can set up over here.

However, if I now move this along Y,

it's doing something as you can see,

but it's not going up to the value of 10.

So we have to define this
a bit more in detail.

For that, let's select
this object once again,

and let's click on Open Drivers Editor.

Then this popup opens up,
which is totally fine.

However, it's not so nice
for recording this tutorial

because it's always in the way.

So down here, let's move this up,

and let's change the Asset
Browser to the driver's editor.

If I middle mouse button click
and move this to the side,

we can see we have this red line here.

And let's hold down Control
+ middle mouse button click,

and drag this around so
we can see it better.

And it looks similar as the graph editor,

because it is indeed some
kind of a graph editor.

Here on the side, we
have the list of drivers.

Currently it will only show us

the drivers of the selected object

because this mouse cursor is active.

Let's disable this,

then we will see all the
drivers for all the objects.

So when I zoom in here,
now we have two points.

You can see this two black
points, which I can select.

And by pressing G, I can
also move them around.

It's doing some weird
snapping here as you can see,

and that's because up here under Auto Snap

newest frame is selected.

Let's disable Auto Snap, then
I can freely move this around.

And this curve, which is
actually just a straight line,

but when I move these handles around here,

you can see I could create a curve,

defines the start and end
point of the controlled value.

That means the first point on
here defines the zero state.

That means when the handle
is at the certain position,

then here we define what the power value

of this emission shader should be.

And up here with this key frame,
we control the final state.

Means that when we move the
handle in a certain position,

then we wanna have the
emission power of 10.

Then you can see we have
a coordinate system here.

We have the horizontal
axis and the vertical axis.

The horizontal axis defines

the change of the value
of the target object,

the handle in this case.

and the vertical axis defines the change

of the owner object here,

which is this object here,

the emission value in this case.

That means here, for example,

I need to move this up to 10
in order to have the end value

at the emission of 10.

So, but fiddling around with
the curve here is a bit tricky.

And also having the possibility

to turn this into a curve is a bit tricky.

So I would suggest to
select everything here,

right click, go to interpolation mode,

and change this to linear.

Then we just have these two points,

which we can select to
change this line here.

So now I don't wanna manually
position this here, somewhere.

It's a bit tricky.

So let's simply press N
to open up the sidebar.

When this point here is
selected under F curve,

we can find the active key frame.

And here we can simply define the values

which we wanna add here.

That means under Value,

we simply type in the end value

because I have the end key
frame selected, basically,

which was 10.

So we wanna have it power of 10.

Then you can see how
this thing is moving up

to 10 on the vertical axis,

and we wanted to move this object here

in the positive direction of 0.08.

And now you can see if
I zoom in a bit closer,

the horizontal axis was
now changed to 0.08.

Meaning if this object changes
the Y position value to 0.08,

then the emission power should be at 10.

And if I move this now over here,

you can see how this dotted lines

versus dot here is changing.

So you can see when I move this object

at which position this is.

So let's set this back to
zero, and now if I move this,

you can see how nicely
the lamb starts to glow.

However, you can see that this handle

is in the center right now.

That means I can move
it into one direction,

but also into the other direction.

And basically,

I want this position
to be the zero position

and this to be there
fully active position.

That means this year was a
position of negative 0.08.

That means we simply have to
select a start key frame here

and define the values for the start.

That means the value
should be zero, of course.

That means the emission of the
lamp appear should be zero.

But the position of this object
should be at negative 0.08.

Now you can see it moved over here.

And now the value is changing

from this position to this here.

That means if I now move
this the full direction here,

it's turning on the light.

So let's place it over here.

Now we edit our first driver.

And as you can see

when understanding what these
key frames here are doing,

it's actually pretty simple.

Now let's select a light object here.

And in the light settings under Power,

let's also add a driver here.

Again, I want to use a handle light.

I wanna change the Y location,

and this should happen in local space.

And now you can see the other
driver was added over here.

This is now selected here again,

let's select everything, right-click,

interpolation set to linear.

And now we again have
these two points here.

So here we wanted to have,
I think, 500 Watts or 250.

We have to test this out.

So let's change the
end point to 250 Watts.

And the position of the
handle should be at 0.08,

as you maybe remember,

and the start position
should be negative 0.08,

and the Watts should be at zero.

That means if I now switch
over to the rendered--

Whoa, what's going on here?

We can see that something's clearly wrong.

And that's because over
here in the driver,

let's go to Edit Driver,

which we also can do over here by the way,

when the driver is selected.

I still have scripted expression enabled.

Let's change this to averaged value,

and now it should do
exactly what we set up.

When I moved this over here,
the light is turning on.

And I think we can do it a bit stronger.

So let's select this,

go to the F curve and
change this to 500 Watts.

And now if I move this,
it will be a bit brighter.

That means if I select it,

we can see that the
value is now 500 Watts.

If I move it a little bit down,

then you can also see how
the value has changed.

So pretty cool.

Now we can control the light intensity

with this handle here.

However, now I wanna control the position

of this object here with the green handle.

For that, let's check the
position of the object.

So when this is fully moved out,

the Z location should be zero.

And let's check when this is moving in,

we wanna have something
like negative 1.76.

So, and we wanna control
this with this handle

when this is rotating around the x-axis

to negative and positive 30 degrees.

So let's select this one here,

right-click on the Z location,
and click on Add Driver.

Averaged value,

here we wanna control this
with the handle position

and the handle should rotate...

I think it was X.

Let's check once again.

Yeah, it was the X rotation.

Let's go back to Edit Driver.

Here we leave Auto Euler,

and here we change this to a local space.

Now we have another curve over here,

under the streetlamp we
have the Z location here.

If you like, you can hide
the other two drivers.

And now let's do the same thing.

Select everything with A, right-click,

interpolation to linear.

And now before we change
these two values here,

there is a little problem because Blender

is not using degrees over here,

it's using radians.

That means to better see what's going on,

let's quickly temporarily
change the scene units here,

the rotation to radians.

That means, let's check
this one here, press R...

But actually let's change this
back to degrees for a second.

And now let's change the
rotation to 30 degrees,

and then back to radians.

And then we have this value over here,

which should be the full rotation we need

in order to move the object here.

Let's Control + C,

copy the value by hovering
our mouse above this,

and then we can change
this back to the degrees.

That means the end value
should be this one here.

Paste this by pressing Control + V.

And it should move the object to zero.

That means the end position
should be zero in this case.

Then let's select the first key frame.

And here the radians should
be negative 0.523, something,

when the handle is moved
into the other direction,

and we had a value of negative 1.765.

Something like this if
I remember correctly.

That means if I rotate this over here,

then this is going down.

Because the start position

is now at the negative rotation value,

which we have over here,

and the end position is up here.

So we define this by
controlling these two values.

If I hold down Control +
middle mouse button click,

change the position here.

We can see it a bit
better. Let's zoom in here.

We can see the position down here

is at negative 1.76 meters,

and the radians is at negative 0.524,

and the positive value is
at zero for the location,

and at 0.5 something positive radians.

So that means all we need to do

in order to set up the
drivers is to add the targets

and then here define the start

and end position of the driver.

And now let's push this
down, turn off the light.

That's disable the overlays, press N.

Now let's move this out
and then turn on the light.

Pretty cool.

It takes a bit time to set up, of course,

but as you can see,

drivers are really powerful

and allow us to control
nearly everything in our scene

with just a few objects.

Yeah. And now you should be
prepared to set up the drivers

for our character rig in the next video.

And if you followed this
video, don't forget to save.