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

isNull() bool Box2d::isNull ( ) const 判断宽和高是否都为零且位于原点 函数调用图: 这是这个函数的调用关系图: