FixedJoint2D 2D关节固定

class in UnityEngine/Inherits from: AnchoredJoint2D

Connects two Rigidbody2D together at their anchor points using a configurable spring.

使用一个可配置的弹簧连接两个2D刚体锚点。

dampingRatio	The amount by which the spring force is reduced in proportion to the movement speed. 通过弹力减少移动速度比例的总数。
frequency	The frequency at which the spring oscillates around the distance between the objects. 在物体之间弹力震动的频率。
referenceAngle	The angle referenced between the two bodies used as the constraint for the joint. 两个身体之间的参考角用作共同的关节。