# :icon-git-commit: Animation Curves

While keyframes define the start and end points of an animation, the animation
curve (or "*interpolation curve*") defines how a clip *moves* from the start to
the end. You may have also heard this referred to as the amount of "easing".

Final Cut gives you just two premade interpolation modes - "linear" or
"smooth":

![](/static/interpolation/fcp_builtin_options.png)

These two modes offer little customization, and not all parameters even support
them both. For example, the scale parameter is limited to linear interpolation;
you can't make it smooth at all!

# Animation in *Curves*

Curves uses fully continuous sliders instead of rigid premade modes, giving you
almost unlimited ways to customize your animations. Giving you as much control
as possible over the animation curve was so important to me when designing
Curves that I named the entire plugin after it!

With Curves, controlling the amount of easing is as simple as adjusting a
slider. For example, here's the "smooth" curve with different amounts of easing
applied:

<video autoplay loop muted playsinline>
   <source src="/static/interpolation/smooth_comparison.mp4"/>
</video>
<p/>

Scale, rotation, and translation keyframes all follow this curve, meaning
everything stays exactly in sync.

Use the shape selector to pick from one of 7 curve shapes.

<img width="500px" src="/static/interpolation/shape_sel.svg"/>
</p>

Use the graph view to visualize how your animation will move over time.

<img width="500px" src="/static/interpolation/graph_view.svg"/>
</p>

Use the parameter settings to dial in the exact curve you want.

<img width="500px" src="/static/interpolation/param_sliders.svg"/>
</p>

You can even keyframe the interpolation curve itself, allowing your clip to
change the interpolation curve without having to cut the clip and reapply the
Curves plugin.

# What is a curve?

An interpolation curve defines the path from the start keyframe to the end
keyframe. In *Curves*, we represent these with graphs. The left side of the
graph represents the *start* keyframe, and the right side represents the *end*
keyframe.

<img class="relight" width="320px" src="/static/interpolation/graphs_explained_light.svg"/>
<img class="redark" width="320px" src="/static/interpolation/graphs_explained.svg"/>
<p/>

Time moves from left to right. As we move further along the curve, we get
closer to the end position and further from the start position. At a given
point in time, the height of the curve tells us how close we are to either
point.

# Working with the Curve Editor

Click to select a curve shape.

<video width="300px" autoplay loop muted playsinline>
   <source src="/static/editor/selecting.mp4"/>
</video>
<p/>

Drag a slider and watch the graph update in realtime.

<video width="300px" autoplay loop muted playsinline>
   <source src="/static/editor/adjusting_smooth.mp4"/>
</video>
<p/>

Even complicated parameters can be quickly adjusted.

<div style="display: flex; gap: 20px;">
   <div style="text-align:center;">
      <video autoplay loop muted playsinline>
         <source src="/static/editor/configuring.mp4"/>
      </video>
   </div>
   <div style="text-align:center;">
      <video autoplay loop muted playsinline>
         <source src="/static/editor/adjusting.mp4"/>
      </video>
   </div>
</div>
<p/>

# Curve Shapes

There are 7 curve shapes to select from, each with their own parameters.

<img class="relight" src="/static/interpolation/modes_light.svg"/>
<img class="redark" src="/static/interpolation/modes_dark.svg"/>
<p/>

## Linear

The simplest kind of animation is *Linear*. It just moves from point A to B in
a straight line. There are no parameters to adjust.

## Smooth

*Smooth* gives you a symmetric curve with a customizable amount of easing and
backing. You may have heard this referred to as "ease both" in other animation
systems.

<img width="400px" src="/static/interpolation/smooth_params.svg"/>
<p/>

<span style="color:#42D473;">**Easing**</span> refers to how "sharp" the curve
is. No easing is the same as linear, and lots of easing is a very quick jump
from A to B in the middle of the two keyframes. See the animation at the top of
the page for a comparison of the easing modes of the smooth curve.

<span style="color:#FF96EC;">**Backing**</span> slides the clip back before and
after the animation. It gives it a cartoonish "bouncy" feeling:

<video width="250px" autoplay loop muted playsinline>
   <source src="/static/interpolation/smoothback_clip.mp4"/>
</video>
<p/>

## Acceleration / Deceleration

<video width="250px" autoplay loop muted playsinline>
   <source src="/static/interpolation/accel_decel_clip.mp4"/>
</video>
<p/>

*Acceleration* and *Deceleration* offer continuously increasing and decreasing
speed curves respectively. You may have heard these referred to as "ease in" or
"ease out". Just like Smooth, you can control the easing and backing.

## Overshoot

<video width="250px" autoplay loop muted playsinline>
   <source src="/static/interpolation/overshoot_clip.mp4"/>
</video>
<p/>

*Overshoot* models springy / elastic things.

<img width="500px" src="/static/interpolation/overshoot_params.svg"/>
<p/>

<span style="color:#42D473;">**Frequency**</span> lets you control the
oscillation frequency as the overshoot settles to a steady state.
<span style="color:#FF96EC;">**Rise Time**</span> controls how long the curve
rises before oscillating and decaying. This can be used to slow down the
animation to make it more subtle.
<span style="color:#5FA2FF;">**Acceleration**</span> controls how sharp the
rising curve is. Larger values give the animation more power.

## Bounce

<video width="250px" autoplay loop muted playsinline>
   <source src="/static/interpolation/bounce_clip.mp4"/>
</video>
<p/>

*Bounce* models bouncy things.

<img width="500px" src="/static/interpolation/bounce_params.svg"/>
<p/>

<span style="color:#42D473;">**Num Bounces**</span> lets you specify how many
bounces should occur. <span style="color:#FF96EC;">**Bounciness**</span>
controls the coefficient of restitution- eg. how bouncy is this object?

The bounce curve is drawn moving downwards rather than upwards like the others
because it looked better this way.

## Custom

*Custom* gives you Bezier handles letting you fully control the shape of the
curve. Click and drag a handle to move it around. Use the zoom buttons (+/-) to
zoom in and out.

<img width="300px" src="/static/interpolation/custom_params.svg"/>
<p/>

# Keyframing the Curve Shape

You can use keyframes to change which curve is applied at different points in
your clip. This lets you change the animation curve without needing to cut the
clip and reapply Curves.

Curve shape keyframes work by adding keyframes to the "Curve Editor" itself.
Use the add keyframe button in the upper left corner of the curve editor to add
your first curve shape keyframe:

<img width="500px" src="/static/editor/curvekeyframe.png"/>
<p/>

Now, move forward or backward and make a change to the curve. A new curve shape
keyframe will be created. Curve shape keyframes are "hold" keyframes, which
means they hold their value constant until the next keyframe. Between curve
shape keyframes the value of the most recent keyframe will be held constant.

You will notice keyframe navigation controls appear in the upper right of the
Curve Editor. Use these to move to the previous or next curve keyframes.

<img width="500px" src="/static/editor/curvekeyframe2.png"/>
<p/>

I recommend only adding curve keyframes in the same frame as position,
rotation, or scale keyframes; if you place a curve shape keyframe in the middle
of a path, your clip will likely jump around when the curve changes.