1. Manipulators是可以用三维进行绘制的的节点，可以将用户行为值化，对其他节点的属性进行modify。
2. 属性值可以通过Channel Box 和Graph Editor进行修改。同其他的dg节点不一样，manipulator直接修改属性值，而不通过plug。
3.可以用以下几种方法是用manipulator：
Create a manipulator on any node in the current scene at any time.
Create and assign a manipulator for a specific type of object.
Create a context tool and associate the manipulator to the context tool. Whenever the context tool is active, the manipulator becomes active and ready for use.
4. 所有的manipulator的function set都是从MFnManip3D派生而来。
（1）FreePointTriadManip:
The FreePointTriadManip provides a point that can be moved anywhere. It has axes for constrained x, y, and z movement and obeys grid snapping, point snapping, and curve snapping.
(2)DirectionManip:
.....详情见document
5 Manipulator Containers:
（1）
通过MPxManipContainer创建Manipulator container.
可以将base manipulators加入到container。
定义从manipulator到attribute的联系。
（2）必要的几个方法：
creator(), initialize(), createChildren(), connectToDependNode()
你也可以通过重写draw函数来自定义manipulator的绘制。
（3）initialize()
静态函数需要注册的。进行一些必要的初始化。
（4）createChildren()
base manipulator加到container里面是通过这个函数的，例子：
MStatus moveManip::createChildren()
{
...
fDistanceManip = addDistanceManip(manipName, distanceName);
fFreePointManip = addFreePointTriadManip(pointManipName, pointName);
...
}
The MPxManipContainer class provides a set of member functions to add individual base manipulators, most of them are named as addXYZManip, where XYZ represents the manipulator name