Animation Clip

The AnimationClip class is the base class for animations. It holds the information of a specific track in a Model asset. It is designed to manage a sequence of keyframes that define the transformation (such as position, rotation, scale) or other animated properties (morphing weights) of the model. These keyframes are interpolated over time to create smooth and dynamic movement. This class is the foundation of the animation system, because it's the core of the Animation Blend Tree

Structure

The base structure of the AnimationClip is explained in this graph.

AnimationClipStructure

  • AnimationClip: Main class that contains a list of AnimationChannels.
  • AnimationChannel: Defines the target of the animation and contains an AnimationCurve.
  • AnimationCurve: Define the sampling information of the specific property animation, containing the keyframes.

AnimationClip Properties

It has the following information:

Property Description
Name The name of the AnimationClip.
Channels The list of AnimationChannel objects.
RootMotionPositionChannel The channel that controls the main model's position, among all the channels.
RootMotionRotationChannel The channel that controls the main model's rotation, among all the channels.
RootMotionNodeIndex The index of the model's root node.
Duration The duration of the animation in seconds.
Framerate The frames per second that the animation has been sampled.
InPlaceMode Indicates how the center of the model is handled. Useful when the model's animation displaces it around the scene but we want to control it. Has the following values:
  • None. (default) The animation is not centered.
  • CenterOnlyPosition. The positions is centered.
  • CenterOnlyRotation. The rotation is centered.
  • Center. Both position and rotation are centered.
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    AnimationChannel

    Each channel defines the target of the animation. This target usually refers to a node, using the index of this node, and to name of the animated property. The animated properties usually are "LocalPosition", "LocalRotation" or "LocalScale", affecting the local transform of the node. The channel also refers to an AnimationCurve, which summarizes the actual animation data.

    Properties

    Property Description
    NodeIndex The index of the node among the Model nodel hierarchy.
    ComponentType The target component type of the animation channel.
    PropertyName The target property of this animation channel.
    Duration Duration (in seconds) of the animation.
    Curve AnimationCurve for this channel.

    AnimationCurve

    This class represents how the value of the channel proerty changes over time, and it's made of keyframes containing the time and value of the curve at a specific moment in time. It's an abstract class, which specific type depends of the type of the channel's property:

    • AnimationCurveFloat.
    • AnimationCurveFloatArray.
    • AnimationCurveQuaterion.
    • AnimationCurveVector2.
    • AnimationCurveVector3.
    • AnimationCurveVector4.

    Every frame, the curve calculates its value interpolating the keyframes.

    Properties

    Property Description
    KeyCount The number of keyframes.
    StartTime The start time of the curve. This is used because not every animation channel animates the property during the animation, only during a specific range
    EndTime The end time of the curve.
    Keyframes Array of the different keyframes of the curve.
    DefaultValue The base value, used for additive blending. Loot at this section for more information.

    AnimationKeyframe

    The keyframe represents the animation state at a specific moment. It contains only two parameters:

    • Time: The time of the keyframe, in seconds.
    • Value: The value of that speficic channel's curve.