add asVector distanceSquare distanceTo get isDegenerate isEqualTo kInvalid kOrigin length negate offset offset operator!= operator* operator* operator* operator* operator*= operator*= operator+ operator+ operator+ operator+= operator+= operator- operator- operator- operator-= operator/ operator/= operator== Point2d Point2d Point2d polarPoint rulerPoint rulerPoint scaleBy scaleBy set set subtract subtract transform x y

subtract() [1/2] Vector2d Point2d::subtract ( const Point2d &  pnt ) const 得到两点之间的矢量, 点 - 点 = 矢量