Box2d Box2d Box2d Box2d Box2d Box2d Box2d Box2d Box2d Box2d center contains contains contains contains deflate deflate deflate deflate deflate empty get get get height inflate inflate inflate inflate inflate intersectWith intersectWith isEmpty isEmptyMinus isEqualTo isIntersect isNormalized isNull kIdentity leftBottom leftTop normalize offset offset offset operator & operator &= operator!= operator* operator* operator*= operator*= operator+ operator+ operator+= operator+= operator- operator- operator-= operator-= operator/ operator/= operator== operator| operator|= rightBottom rightTop scaleBy set set set set set set size swapTopBottom unionWith unionWith unionWith unionWith width xmax xmin ymax ymin

unionWith() [2/4] Box2d& Box2d::unionWith ( const Box2d &  box ) 合并一个矩形框（两者都是规范化矩形） 设置本矩形框为本矩形框和另一个矩形框的并集。 如果其中一个为空矩形，则直接设置为另一个矩形框， 非规范化矩形将视为空矩形。 参数 box 另一个矩形框，必须规范化，否则视为空矩形 返回 本矩形的引用，并集，规范化矩形