| curve | Curve to query. | 
| index | キーフレームのインデックス | 
TangentMode Returns the tangent mode.
Retrieves the right tangent mode of the keyframe at a specific index.
        The Curve Editor uses the keyframe tangent mode to automatically generate tangents.
See Also: AnimationUtility.GetKeyLeftTangentMode, AnimationUtility.GetKeyBroken.