add angle angle2 angledVector angleTo angleTo2 crossProduct distanceToVector dotProduct get isCodirectionalTo isCodirectionalTo isDegenerate isEqualTo isLeftOf isOppositeTo isOppositeTo isParallelTo isParallelTo isPerpendicularTo isPerpendicularTo isRightOf isUnitVector isZeroVector kIdentity kXAxis kYAxis length lengthSquare negate normalize operator!= operator* operator* operator* operator* operator* operator*= operator*= operator+ operator+= operator- operator- operator-= operator/ operator/ operator/= operator== perpVector projectResolveVector projectScaleToVector resolveVector resolveVector scaleBy scaleBy scaledVector set set setAngleLength setLength subtract transform unitVector Vector2d Vector2d Vector2d x y

normalize() bool Vector2d::normalize ( const Tol &  tol = Tol::gTol() ) 矢量单位化 即将本矢量的长度改成1，如果本矢量为零矢量，则不改变本矢量 参数 tol 判断的容差，用到其长度容差 返回 如果本矢量为零矢量，则返回false，否则返回true 函数调用图: 这是这个函数的调用关系图: