【Properties–属性– 材质模块 – Houdini帮助文档中文版】
Properties vs. Materials–属性vs 材质
Aside from shaders, every renderer defines certain properties of objects. If these properties are defined on an object, their values will be sent to the renderer if the values are non-default.
除了材质，每个渲染器都定义了物体的特定属性。如果这些属性在物体上辈定义了，这些数值会被发送到渲染器中（如果它们不是默认参数的话）。
However, there is also a Properties SHOP. This doesn’t represent a shader per-se. Rather it provides a place to put object properties. So, amaterial can have a Properties SHOP as one of the shaders inside. Any object which has such a material applied to it will pick up the properties that are defined on the material.
但是，还有一个属性SHOP。它并不代表一个材质。相反,它提供了一个放置属性的地方。所以，一个材质可以有一个 Properties SHOP 节点（作为内部的材质）。任何有被应用该材质的物体都会拾取在材质中定义的属性。
This is useful, for example, to use in IFD and RIB. In IFD and RIB, the displacement bounds is a parameter which is defined outside of the displacement shader. However, by placing a properties SHOP in the displacement material, it is possible to add the displacement bound property and tie its value to the displacement amount in the shader. This is more convenient because you no longer have to worry about setting displacement bounds, since the property is automatically defined in thematerial.
这是非常有用的,例如，要在IFD和RIB中使用它。在IFD和RIB中，置换边界是一个顶置换材质外框的参数。但是，通过在置换材质中放置一个 properties SHOP 节点，就可以添加置换边界属性，并将该值绑定到材质的置换数量参数上。这是非常方便的，因为你不再需要担心设置置换的边界，因为该属性已经在材质中自动定义了。
Promotion of material parameters
Clicking on the material tile lets you automatically promote all the shader parameters. This is a short-cut for bringing up the parameter editor and adding extra links to the shader parameters in the subnetwork.
–右击材质的tile可以让你自动提取材质的所有参数。这是一个快捷的打开参数编辑器并添加额外的连接到材质参数中的方法。
Promoting material parameters does more than provide a unified interface to the material, it also allows parameters to be overridden at the object (or SOP) level.
—提取材质参数不仅仅是给材质提供一个统一界面，它还允许参数在物体级别被覆盖。
Inheritance of properties——属性的继承
Properties may be defined in many various places in Houdini. The precedence order is as follows:
—在Houdini中属性可以在有很地方来定义。其优先权是：
Primitive attribute material assignment —Primitive属性
Object parameters –物体参数
Object level material assignment–物体级别的参数
Output driver properties –输出驱动器的属性
Renderer default values –渲染器的默认值
