Avatar是什麼

Avatar是什麼

Working with humanoid animations

The Mecanim Animation System is particularly well suited for working with animations for humanoid skeletons. Since humanoid skeletons are used extensively in games, Unity provides a specialized workflow, and an extended tool set for humanoid animations.Because of the similarity in bone structure, it is possible to map animations from one humanoid skeleton to another, allowing retargeting and inverse kinematics. With rare exceptions, humanoid models can be expected to have the same basic structure, representing the major articulate parts of the body, head and limbs. The Mecanim system makes good use of this idea to simplify the rigging and control of animations. A fundamental step in creating a animation is to set up a mapping between the simplified humanoid bone structure understood by Mecanim and the actual bones present in the skeleton; in Mecanim terminology, this mapping is called an Avatar. The pages in this section explain how to create an Avatar for your model.

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Avatar其實就是一個映射表，記錄着動畫骨骼與真實骨骼的映射信息

public class Avatar : Object
{
    private Avatar()
    {
    }
    // Return true if this avatar is a valid mecanim avatar. It can be a generic avatar or a human avatar.
    extern public bool isValid
    {
        [NativeMethod("IsValid")]
        get;
    }
    // Return true if this avatar is a valid human avatar.
    extern public bool isHuman
    {
        [NativeMethod("IsHuman")]
        get;
    }
    extern public HumanDescription humanDescription
    {
        get;
    }
    .......
}
 public struct HumanDescription
    {
        [NativeName("m_Human")]
        public HumanBone[]      human;
        [NativeName("m_Skeleton")]
        public SkeletonBone[]   skeleton;

        internal float  m_ArmTwist;
        internal float  m_ForeArmTwist;
        internal float  m_UpperLegTwist;
        internal float  m_LegTwist;
        internal float  m_ArmStretch;
        internal float  m_LegStretch;
        internal float  m_FeetSpacing;
        internal float  m_GlobalScale;

        internal string  m_RootMotionBoneName;

        internal bool   m_HasTranslationDoF;

        internal bool   m_HasExtraRoot;
        internal bool   m_SkeletonHasParents;

        public float    upperArmTwist { get { return m_ArmTwist; } set { m_ArmTwist = value; }   }
        public float    lowerArmTwist { get { return m_ForeArmTwist; } set { m_ForeArmTwist = value; }   }
        public float    upperLegTwist { get { return m_UpperLegTwist; } set { m_UpperLegTwist = value; }     }
        public float    lowerLegTwist { get { return m_LegTwist; } set { m_LegTwist = value; }   }
        public float    armStretch { get { return m_ArmStretch; } set { m_ArmStretch = value; }  }
        public float    legStretch { get { return m_LegStretch; } set { m_LegStretch = value; }  }
        public float    feetSpacing { get { return m_FeetSpacing; } set { m_FeetSpacing = value; }   }
        public bool     hasTranslationDoF { get { return m_HasTranslationDoF; } set { m_HasTranslationDoF = value; }}
    }

HumanDescription中的HumanBone應是映射保存的地方。

Avatar的意義

Retargeting of Humanoid animations

One of the most powerful features of Mecanim is retargeting of humanoid animations. This means that with relative ease, you can apply the same set of animations to various character models. Retargeting is only possible for humanoid models, where an Avatar has been configured, because this gives us a correspondence between the models’ bone structure.

也就是說Avatar是在動畫重定向中構造出來的。Avatar用於動畫重定向技術。