Use Animation curves

This topic discusses the Property list, Animation curves and its keys, adding and modifying keyframes, and rotation interpolation types.

The Property list

In an Animation ClipAnimation data that can be used for animated characters or simple animations. It is a simple “unit” piece of motion, such as (one specific instance of) “Idle”, “Walk” or “Run”. More info
See in Glossary, if an animatable property has Animation Curve, this means that the value of the property changes over time. In the property list area of the Animation View (on the left), all the currently animated properties are listed. With the Animation View in Dope Sheet mode, the animated values for each property appear only as linear tracks, however in Curves mode, you can see the changing values of properties visualized as lines on the graph. The curves still exist regardless of which mode you use: the Dope Sheet mode provides a simplified view of the data by indicating only when a keyframe occurs.

In Curves mode, the Animation CurvesAllows you to add data to an imported clip so you can animate the timings of other items based on the state of an animator. For example, for a game set in icy conditions, you could use an extra animation curve to control the emission rate of a particle system to show the player’s condensing breath in the cold air. More info
See in Glossary have colored curve indicators. Each color represents one of the selected properties in the property list. For information on how to add curves to an animation property, refer to the section on Using the Animation View.

Curves, keys and keyframes

An Animation Curve has multiple keys which are control points that the curve passes through. These are visualized in the Curve Editor as small diamond shapes on the curves. A frame in which one or more of the shown curves have a key is called a keyframeA frame that marks the start or end point of a transition in an animation. Frames in between the keyframes are called inbetweens.
See in Glossary.

The Curve Editor only shows curves for the selected properties. If you have selected multiple properties in the property list, the curves display together. If a property has a key at the currently previewed frame, the curve indicator changes to a diamond shape.

Add and modify keyframes

You can add a keyframe at the currently previewed frame by clicking the Keyframe button.

A keyframe can be added at the currently previewed frame by clicking the Keyframe button. This will add a keyframe to all currently selected curves. Alternatively you can add a keyframe to a single curve at any given frame by double-clicking the curve where the new keyframe should be. It is also possible to add a keyframe by right-clicking the Keyframe Line and select Add Keyframe from the context menu. Once placed, keyframes can be dragged around with the mouse. It is also possible to select multiple keyframes to drag at once. Keyframes can be deleted by selecting them and pressing Delete, or by right-clicking on them and selecting Delete Keyframe from the context menu.

Animatable properties

The Animation View can be used to animate much more than just the position, rotation, and scale of a Game Object. The properties of any ComponentA functional part of a GameObject. A GameObject can contain any number of components. Unity has many built-in components, and you can create your own by writing scripts that inherit from MonoBehaviour. More info
See in Glossary and MaterialAn asset that defines how a surface should be rendered. More info
See in Glossary can be animated - even the public variables of your own scriptsA piece of code that allows you to create your own Components, trigger game events, modify Component properties over time and respond to user input in any way you like. More info
See in Glossary components. Making animations with complex visual effects and behaviors is only a matter of adding Animation Curves for the relevant properties.

The following types of properties are supported in the animation system:

• Float
• Color
• Vector2
• Vector3
• Vector4
• Quaternion
• Boolean

Arrays are not supported and neither are structs or objects other than the ones listed above.

For boolean properties, a value of 0 equals False while any other value equals True.

Here are a few examples of the many things the Animation View can be used for:

• Animate the Color and Intensity of a Light to make it blink, flicker, or pulsate.
• Animate the Pitch and Volume of a looping Audio SourceA component which plays back an Audio Clip in the scene to an audio listener or through an audio mixer. More info
  See in Glossary to bring life to blowing wind, running engines, or flowing water while keeping the sizes of the sound assets to a minimum.
• Animate the Texture Offset of a Material to simulate moving belts or tracks, flowing water, or special effects.
• Animate the Emit state and VelocitiesA vector that defines the speed and direction of motion of a Rigidbody
  See in Glossary of multiple Ellipsoid Particle Emitters to create spectacular fireworks or fountain displays.
• Animate variables of your own script components to make things behave differently over time.

When using Animation Curves to control game logic, please be aware of the way animations are played back and sampled in Unity.

Rotation Interpolation Types

In Unity rotations are internally represented as QuaternionsUnity’s standard way of representing rotations as data. When writing code that deals with rotations, you should usually use the Quaternion class and its methods. More info
See in Glossary. Quaternions consist of .x, .y, .z, and .w values that should generally not be modified manually except by people who know exactly what they’re doing. Instead, rotations are typically manipulated using Euler Angles which have .x, .y, and .z values representing the rotations around those three respective axes.

When interpolating between two rotations, the interpolation can either be performed on the Quaternion values or on the Euler Angles values. The Animation View lets you choose which form of interpolation to use when animating Transform rotations. However, the rotations are always shown in the form of Euler Angles values no matter which interpolation form is used.

Quaternion Interpolation

Quaternion interpolation always generates smooth changes in rotation along the shortest path between two rotations. This avoids rotation interpolation artifacts such as Gimbal Lock. However, Quaternion interpolation cannot represent rotations larger than 180 degrees, due to its behavior of always finding the shortest path. (You can picture this by picking two points on the surface of a sphere - the shortest line between them will never be more than half-way around the sphere).

If you use Quaternion interpolation and set the numerical rotation values further than 180 degrees apart, the curve drawn in the animation window will still appear to cover more than a 180 degree range, however the actual rotation of the object will take the shortest path.

When using Quaternion interpolation for rotation, changing the keys or tangents of either the x, y or z curve may also change the values of the other two curves, since all three curves are created from the internal Quaternion representation. When using Quaternion interpolation, keys are always linked, so that creating a key at a specific time for one of the three curves (x, y or z) will also create a key at that time for the other two curves.

Euler Angles Interpolation

Euler Angles interpolation is what most people are used to working with. Euler Angles can represent arbitrary large rotations and the .x, .y, and .z curves are independent from each other. Euler Angles interpolation can be subject to artifacts such as Gimbal Lock when rotating around multiple axes at the same time, but are intuitive to work with for simple rotations around one axis at a time. When Euler Angles interpolation is used, Unity internally bakes the curves into the Quaternion representation used internally. This is similar to what happens when importing animation into Unity from external software. Note that this curve baking may add extra keys in the process and that tangents with the Constant tangent type may not be completely precise at a sub-frame level.