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Unity Engine

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Unity Engine

Keyframe

A keyframe that can be injected into an AnimationCurve.
Read time 3 minutesLast updated 2 days ago

Definition

  • Type: Struct
  • Namespace: UnityEngine
  • Assembly: UnityEngine.CoreModule
public struct Keyframe

Remarks

Keyframes are used to control how the value of an AnimationCurve changes over time. Each Keyframe is determined by its position in the AnimationCurve through the Keyframe.time (horizontal axis) and Keyframe.value (vertical axis) properties. You can control how interpolation is handled between different Keyframes and the AnimationCurve slopes through the Keyframe.inTangent, Keyframe.outTangent, Keyframe.weightedMode, Keyframe.inWeight and Keyframe.outWeight properties. Note that unlike what the Keyframe.time property name might imply, it is not actually tied to time and can simply be thought of as a position on the horizontal axis of a two-dimensional space.
Hermite Segment
When both keyframes weightedMode are set to 
WeightedMode.None
, the curve segment is interpolated using a Hermite curve algorithm. Hermite evaluates faster than Bezier and is the default weightedMode for a Keyframe.
Bezier Segment
Setting weightedMode will change how the neighbouring segments are interpolated. Weighted segments are interpolated using a Bezier curve algorithm. For a given weighted keyframe, the interpolating function uses the Keyframe.outWeight value and the next keyframe’s Keyframe.inWeight alongside both keyframes values to calculate the curve. If no weight is set (when either keyframe Keyframe.weightedMode is set to 
WeightedMode.None
), then a weight value of 1/3 is used.
Additional Resources: AnimationCurve.AddKey, AnimationCurve.keys, AnimationCurve.Evaluate.

Examples

using UnityEngine;//This script makes the GameObject move back and forth from -5 to +5 on the x-axispublic class KeyFrameExample : MonoBehaviour{    AnimationCurve  animCurve = null;    void Start()    {        Keyframe[] ks = new Keyframe[2];        ks[0] = new Keyframe(0f, -5f); //Create a Keyframe at time 0 with a value of -5f        ks[1] = new Keyframe(1f, 5f); //Create a Keyframe at time 1 with a value of 5f        animCurve = new AnimationCurve(ks);        animCurve.postWrapMode = WrapMode.PingPong; //Set the WrapMode to PingPong in order to make the GameObject go back and forth    }    void Update()    {        if (animCurve != null)            transform.position = new Vector3(animCurve.Evaluate(Time.time), 0.0f, 0.0f);    }}

Constructors

Constructor

Description

Keyframe(System.Single,System.Single)Creates a keyframe with a Keyframe.weightedMode defaulting to WeightedMode.None.
Keyframe(System.Single,System.Single,System.Single,System.Single)Creates a keyframe with a Keyframe.weightedMode defaulting to WeightedMode.None.
Keyframe(System.Single,System.Single,System.Single,System.Single,System.Single,System.Single)Creates a keyframe with a Keyframe.weightedMode defaulting to WeightedMode.Both.

Properties

Property

Description

inTangentSets the incoming tangent for this key. The incoming tangent affects the slope of the curve from the previous key to this key.
inWeightSets the incoming weight for this key. The incoming weight affects the slope of the curve from the previous key to this key.
outTangentSets the outgoing tangent for this key. The outgoing tangent affects the slope of the curve from this key to the next key.
outWeightSets the outgoing weight for this key. The outgoing weight affects the slope of the curve from this key to the next key.
timeThe time of the keyframe.
valueThe value of the curve at keyframe.
weightedModeWeighted mode for the keyframe.