Density Changing the density here affects the mass of the GameObject’s associated Rigidbody 2D. If you set the value to zero, its associated Rigidbody 2D ignores the Circle Collider 2D for all mass calculations, including centre of mass calculations. Note that this option is only available if you have selected Use Auto Mass in an associated Rigidbody 2D. Material 一种物理材质，可用于确定碰撞的属性（例如摩擦和弹性）。 Is Trigger 如果希望 2D 圆形碰撞体作为触发器运行，请选中此框。 Used by Effector 如果希望 2D 圆形碰撞体由附加的 2D 效应器使用，请选中此框。 Offset 2D 圆形碰撞体几何形状的局部偏移。 Radius 圆形的半径（采用局部空间单位）。