All language subtitles for 4. Modifying Parts of a Curve

So we took a look at editing the curves in the Curve Editor.

Now let's take a look at how we can perform some modifications to those curves.

Well, how is modifying different from editing?

Let's take a look first by adjusting the slope of a curve.

To adjust the slope of a curve, select a keyframe,

and a red tangent handle will appear on both sides of the key.

So if I just click on this,

you'll see these red tangent handles appear with extra dots on either end.

Now just drag the edge of the red tangent handle and

see how the curve follows the handle.

This is what we mean by modifying the curve.

You can also go in here and double-click on these numbers and

change them if you want to put in specific values.

Now let's talk about interpolating the curve.

Interpolation refers to the specific method or algorithm the

computer's using to determine how the curve is going to change

direction on the keyframe that you've given it.

By default, the Curve Editor is presenting a smooth interpolation,

meaning it's using an algorithm to find the smoothest way to interpret the

motion between the two keyframes you've defined for it.

So if we see that we've given the computer a keyframe here,

and a keyframe here,

what it's doing is it's moving the animation from that keyframe to

this keyframe in as smooth a way as possible,

and it'll make sense a little more when we look at the

different interpolation methods in a second.

If I select this keyframe and right-click,

and go to Interpolation,

I have a list of different interpolation methods that I can pick,

and if I pick Constant,

you'll see that the keyframe changes from a Smooth interpolation

method to a Constant interpolation method.

So, what it's doing is it's defining a stepped key in our animation here.

It's saying that the value that we're receiving on this key should be

held until we get a value again at the next key.

So this value will be constant until the key

changes on this frame to a new value.

So if we play this animation,

you'll notice here in the Viewer that the earth is

moving along a smoothed curve.

This is a smoothed curve, and as we reach this Constant interpolation method,

what it's going to do is it's going to hold and then it's

going to jump as soon as it receives new data.

Boom, it jumped.

So that's what a Constant interpolation method is.

The next interpolation method is a Linear interpolation method.

So if we go in here and we switch this to Linear,

what Linear does is it produces a sharp change at

keyframes and straight lines between them.

So, if we play this animation back,

(Animation playing) you'll see how sharp that keyframe is,

and we can move these tangent handles to soften that and get back to a

more smoothed animation to smooth your animation out.

And if we play this back, it's a little smoother,

but you use the Linear method if you want a sharp point in

your animation or a quick changeover.

We can exaggerate that a little more by dragging these tangent handles down,

and by replaying our animation,

and you can even see the visualization showing us how

sharp that bounce is going to be.

Now we can revert that back to a Smooth interpolation method,

which is the next one down on the list by just checking Smooth,

and that's going to bring us back to that Smooth

curve that we had at the beginning,

and I'm kind of going to gloss over this because we've seen how Smooth

works and you should be pretty familiar with it.

The next point interpolation that we're going to look at is Catmull-Rom.

So, if I take one of these points and I drag it way up here,

what Catmull-Rom does is it's going to take the weighted average of the two

points: the point to the left and the point to the right of it.

So if we take a look at these points and we look at their tangents,

and then we go to this point, if I right- click,

do a Catmull-Rom,

what it's going to do is it's just going to smooth out all of

these curves to work together in an algorithm that just

provides a smoother kind of smooth.

If we go back here and we right-click and we pick the Cubic interpolation,

you'll see that what the Cubic interpolation does is it sets the

slope so that the second derivative is continuous.

Now just to put that in English,

the second derivative measures how the rate of change

of a quantity is itself changing.

So this is basically just another type of smoothing that you can use

that takes into consideration the points around it.

The next interpolation method is Horizontal,

which is an easy one,

that's just going to set all of the tangents to a horizontal slope.

So the last interpolation method I'll talk about is the

Break Tangent interpolation method.

So if I select one of these points here and we have this dotted

line signifying that this is a Unified tangent,

I'll just move this and you'll see that the whole tangent moves together,

but if I select the keyframe, right-click,

and say break, what it's going to do is it's going to break this tangent in two.

And then you can move both sides independently of each other,

just to get the exact curve that you want.

Now, once they go back into a straight line, they'll snap back together.

So if they're broken,

and I move these in such a way where they become a straight line again,

you'll notice that they snap back into revolving around each other.

So those are the different ways that you can modify parts of a curve.

In the next clip,

we'll be taking a look at repeating or reversing parts of the curve.

We can also negate a curve,

which means that we can take part of the curve and just

flip it around to be its negative self.

So there are some pretty fun ways of manipulating the curves

that we'll take a look at in the next clip.