In Maya, a directed acyclic graph (DAG), defines elements such as the position, orientation, and scale of geometry. The DAG is composed of two types of DAG nodes, transforms and shapes.
在Maya里，几何体的位置，方向和缩放元素是由DAG（有向无环图）定义的。DAG有两类DAG节点组成：transform节点和shape节点。
Transform nodes—Maintain transformation information (position, rotation, scale, etc.) as well as parenting information. For example, if you model a hand, you would like to apply a single transformation to rotate the palm and fingers, rather than rotating each individually—in this case the palm and fingers would share a common parent transformation node.
Transforms节点包含了变换信息（位置，旋转，缩放等等）以及父子级信息。例如，如果你想做一只手，你更希望用一个旋转信息控制手掌和手指，而不是让他们各自单独移动。在这种情况下，手掌和手指会共享同一个父级transform节点。
Shape nodes—Reference geometry and do not provide parenting or transformation information.
Shape节点是个参考几何体，并且不提供父子级信息和变换信息。
In the simplest case, the DAG describes how an instance of an object is constructed from a piece of geometry. For example, when you create a sphere, you create both a shape node (the sphere) and a transformation node that allows you to specify the sphere’s position, scale, or rotation. The transformation node’s shape node is its child.
在最简单的情况下，DAG描述了一个几何体是如何组成一个对象的实体的。例如，当你创建一个球的时候，你同时创建了一个shape节点（球）和一个transform节点。transform节点允许你给球设定位置，缩放或者旋转角度。transform节点的shape节点是它的子级。
