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Houdini 20.5 Geometry
Houdini 20.5 几何

Geometry attributes   几何体属性

Describes how Houdini represents geometry using details, primitives, points, vertices, and attributes.
描述 Houdini 如何使用细节、基本体、点、顶点和属性表示几何体。

On this page   此页面上

Attributes   属性

Attributes are named values stored on vertices, points, primitives, and objects. Point color, position, UV coordinates , spline weight (), and normal, for example, are stored as point attributes.W
属性是存储在顶点、点、基本体和对象上的命名值。例如，点颜色、位置、UV 坐标 、样条线权重（）和法线存储为点属性。W

  • Houdini sets some point attributes that you can use in expressions. For example, you could set the per-point color based on the vertical position () of the point.PY
    Houdini 设置了一些可以在表达式中使用的点属性。例如，可以根据点的垂直位置（）设置逐点颜色。PY

  • You can set certain attributes manually, and if the attributes are present, they will be used by Houdini. For example, the dynamics solvers and rendering engines will often use certain attributes on the geometry if they exist.
    您可以手动设置某些属性，如果属性存在，它们将被 Houdini 使用。例如，动力学解算器和渲染引擎通常会使用几何体上的某些属性（如果存在）。

  • You can also set your own custom attributes to be used by node expressions, scripts, exporters, etc.
    您还可以设置自己的自定义属性，以供节点表达式、脚本、导出器等使用。

The surface nodes in the Attributes group of the tab menu set different types of attributes. You can also set or create arbitrary attributes using the Attribute SOP
选项卡菜单的“属性”（Attributes）组中的曲面节点设置不同类型的属性。还可以使用属性 SOP 设置或创建任意属性.

To see the attributes on a node’s geometry, click on the node in the network editor and choose Spreadsheet to open the geometry spreadsheet for the node.
要查看节点几何体的属性，请在网络编辑器中单击该节点，然后选择 “工作表 ” 以打开该节点的几何体电子表格 。

Geometry components   几何部件

You can create and set attributes using the generic Attribute Create surface node, or the Vertex, Point, and Primitive nodes. You can attach attributes to vertices, points, and primitives (e.g. polygon faces), or the entire piece of geometry (called the detail level).
可以使用常规的“属性创建”（Attribute Create）曲面节点或“顶点”（Vertex）、“点”（Point）和“基本体”（Primitive）节点来创建和设定属性 。您可以将属性附加到顶点、点和基本体（例如多边形面）或整个几何体（称为细节级别）。

Attribute precedence   属性优先级

When two components in the same geometry have an attribute with the same name, the attribute on the “lower level” of geometry is used:
当同一几何体中的两个组件具有同名属性时，将使用几何体“较低级别”上的属性：

  • Vertex attributes override:
    顶点属性覆盖：

    • Point attributes, which override:
      点属性，覆盖：

      • Primitive attributes, which override:
        基本属性，覆盖：

        • Detail (whole geometry) attributes
          细节 （整个几何体）属性

Applying nodes based on attribute values
基于属性值应用节点

Most surface nodes have a Group field that lets you enter a named group or pattern to select the components the node should apply to. This field recognizes special syntax that allow you to select components by the value of an attribute. For example, in a Point node’s Group field, selects all points whose attribute is greater than .@foo>5foo5
大多数曲面节点都有一个 “组”（Group） 字段，允许您输入命名组或阵列以选择节点应应用到的组件。此字段识别允许您按属性值选择组件的特殊语法。例如，在“ 点” 节点的“ 组” 字段中，选择属性大于的所有点。@foo>5foo5

See the section on manually specifying groups for more information.
有关详细信息，请参阅手动指定组一节。

Dictionary attributes   字典属性

Since Houdini 18.5, SOP geometry supports dictionary attributes, an attribute type where each element (point, vertex, primitive/face, or the whole geometry/detail) can store a set of key/value pairs. Dictionary attributes can be used to store:
从 Houdini 18.5 开始，SOP 几何支持字典属性，一种每个元素（点，顶点，基元/面，或整个几何/细节）都可以存储一组键/值对的属性类型。字典属性可用于存储：

  • Complex “blind” element data, such as game engine data, or data for a foreign geometry format that Houdini does not support natively.
    复杂的“盲”元素数据，例如游戏引擎数据，或 Houdini 本机不支持的外国几何格式的数据。

  • Metadata about geometry on the detail (whole geometry).
    有关详图上几何图形的元数据（整个几何图形）。

  • Parameter values of the node that creates different elements for debugging. You could even store a node network as geometry by representing nodes with points, and their wires and parameters in a dictionary point attribute. See the Attribute From Parms SOP
    创建用于调试的不同元素的节点的参数值。您甚至可以将节点网络存储为几何体，方法是用点表示节点，并在字典点属性中表示节点的关联和参数。参见参数 SOP 中的属性    .

You can also create a dictionary array attribute, where the attribute value is an array of dictionaries, rather than a single dictionary.
还可以创建字典数组属性，其中属性值是字典数组 ，而不是单个字典。

Dictionary keys are strings. Dictionary values can be strings, numbers, arrays, or a (nested) dictionary. Dictionary attributes essentially have the same data model as JSON. In fact, UI such as the geometry spreadsheet displays the contents of a dictionary attribute like a JSON-encoded string.
字典键是字符串。字典值可以是字符串、数字、数组或（嵌套的）字典。 字典属性本质上具有与 JSON 相同的数据模型 。实际上，像几何图形电子表格这样的 UI 显示字典属性的内容，就像 JSON 编码的字符串一样。

Currently, support for dictionary attributes is mostly in Python, VEX, and VOPs. You can manipulate dictionary attributes on geometry using VEX snippets in Attribute Wrangle, or with a Python SOP. There is also simple support for reading key values in parameter expressions.
目前，对字典属性的支持主要在 Python、VEX 和 VOP 中。您可以使用属性矩形中的 VEX 片段或 Python SOP 操作几何体上的字典属性 。还支持在参数表达式中阅读键值。

Language   语言

Support   支持

VEX/VOPs

  • Use the standard VEX functions for reading attribute values to get the entire dictionary as a VEX dict type.
    使用标准 VEX 函数来阅读属性值 ，以获取作为 VEXdict 类型的整个字典。

  • You can check for the existence of a key with hasdetailattrib using as the name.‹attr_name›.‹key›
    您可以使用 hasdetailattrib 作为名称来检查密钥是否存在。<$attr_name<$.<$key<$

  • You can bind with a dictionary attribute in a VEX snippet with (or for a dictionary array attribute).d@food[]@foo
    您可以在 VEX 代码段中使用（或用于字典数组属性）绑定字典属性。d@food[]@foo

  • You can use to index. However, VEX has return type inference, so you may need return casts to do this. (The dictionary entry is any type, but must be resolved at compile time to a specific type.) Referring to a missing key returns a zero-value.[]
    您可以使用索引。但是，VEX 具有返回类型推断，因此您可能需要返回强制转换来执行此操作。(The 字典条目是任何类型，但必须在编译时解析为特定类型。）引用缺少的键将返回零值。[]

  • VEX/VOPs has functions for manipulating dictionaries. In addition, several functions for arrays also work with objects. For example, len on a returns the number of items in the dictionary, and isvalidindex tells whether a key is present in the dictionary.dictdict
    VEX/VOPs 具有操作字典的功能。此外，数组的几个函数也可以用于对象。例如，a 上的 len 返回字典中项目的数量，而 isvalidindex 告诉字典中是否存在键。 法令法令

  • keys returns the dictionary keys as an array of strings. (It is not possible to have an equivalent function for values since arrays must be single type in VEX).
    keys 将字典键作为字符串数组返回。(It 不可能有等效的值函数，因为 VEX 中的数组必须是单一类型）。

  • The set function lets you build up a dictionary from alternating key and value arguments:
    set 函数允许你从交替的键和值参数中构建一个字典：

    dict foo = set( 'key1', 3.2, 'key2', 'stringvalue');

See the documentation for the VEX dict type for more information on working with types in VEX.dict
有关在 VEX 中使用类型的更多信息，请参见 VEX dict 类型的文档。dict

Python

  • Use the standard hou.Geometry methods (for example, hou.Geometry.attribValue for detail attributes) to read a dictionary attribute. This will return the entire dictionary as a Python containing Python types (, , , , ).dictintfloatstrlistdict
    使用标准 hou.Geometry 方法（例如，hou.Geometry.attribValue 用于详细信息属性）读取字典属性。这将返回整个字典，作为一个包含 Python 类型（，）的 Python。dictintfloat 字符串列表 dict

  • Since the attribute methods return a pure Python structure, once you read the attribute value you can use regular Python to manipulate the data. For example, to get the number of items in the dictionary, to get the value associated with a key, etc.len()dict["‹key›"]
    由于属性方法返回一个纯 Python 结构，因此一旦读取了属性值，就可以使用常规 Python 来操作数据。例如，获取字典中的条目数，获取与键相关的值等。len（）dict["<$key<$"]

Expressions   表达式

  • You can read the value of a dictionary key in an expression with the standard functions for reading attribute values (detail, point, vertex, prim), using as the name.‹attr_name›.‹key›
    使用作为名称，可以使用阅读属性值（ 细节 、 点 、 顶点 、 顶点 ）的标准函数读取表达式中字典键的值。<$attr_name<$.<$key<$

  • If you use the string attribute functions (details, points, vertexs, prims) to read the whole attribute value, it will return a JSON-encoded string. However, there are no JSON-parsing expression functions, and limited string manipulation functions, to deal with such a string in an expression.
    如果使用字符串属性函数（details、points、vertexs、prims）读取整个属性值，它将返回 JSON 编码的字符串。但是，没有 JSON 解析表达式函数和有限的字符串操作函数来处理表达式中的此类字符串。

Tip  尖端

The Attribute Create node only creates an empty dictionary attribute. Currently, the best way to set dictionary values in a geometry network is with a Python SOP or Attribute Wrangle
“ 属性创建 ”节点仅创建空字典属性。目前，在几何网络中设置字典值的最佳方法是使用 Python SOP 或属性矩形.

Intrinsic attributes   内在属性

Intrinsic attributes are computed values derived from the geometry that you can access as if they were attributes.
内部属性是从几何体中导出的计算值 ，您可以像访问属性一样访问这些计算值。

Examples of intrinsic attributes
固有属性的示例

Detail   详细

intrinsic:pointcount

Number of points in the geometry
几何中的点数

Detail/primitive   细节/原始

intrinsic:bounds

Bounding box of the geometry
几何的边界框

Primitive   原始

intrinsic:measuredarea

Surface area of the geometry.
几何图形的表面积。

Primitive   原始

intrinsic:memoryusage

Amount of memory used by the primitive.
基元使用的内存量。

To...  去...Do this  这么做

See the available intrinsic attributes
查看可用的内部属性

  • The command line utility prints a list of all known intrinsic attributes.ginfo -I
    命令行实用程序打印所有已知内在属性的列表。ginfo -I

  • You can show intrinsic attributes in the geometry spreadsheet. By default they are not shown.
    可以在几何图形电子表格中显示固有属性。默认情况下，它们不显示。

    If you are viewing geometry at a component level that has intrinsic attributes, you can use the Intrinsics menu to show all intrinsics or choose the intrinsics to show in the spreadsheet.
    如果在具有内部属性的组件级别查看几何体，则可以使用“内部”（Intrinsics） 菜单显示所有内部，或选择要在电子表格中显示的内部。

  • The Inspect tool can show the intrinsic attributes that are available on the inspected geometry.
    “ 检查”工具可以显示被检查几何体上可用的固有属性。

Use intrinsic attributes
使用内部属性

Tip  尖端

Despite the name, some “intrinsic” attributes can actually be written to, causing Houdini or Mantra to change some internal setting. For example, you can set the intrinsic attribute on a packed primitive.intrinsic:unexpandedfilename
尽管名称，一些“内在”属性实际上可以写入，导致胡迪尼或曼特拉改变一些内部设置。例如，您可以在打包的基元上设置内部属性。intrinsic：未扩展文件名

Tip  尖端

Bounding box intrinsic attributes, like or are returned in (xmin, xmax, ymin, ymax, zmin, zmax) order.intrinsic:boundsintrinsic:packedbounds
边界框固有属性，如或，按（xmin，xmax，ymin，ymax，zmin，zmax）顺序返回。intrinsic：bounds 内部：压缩边界

Higher and lower precision storage
高低精度存储

You can choose the numeric precision of attributes you create with the Attribute Create node, and/or convert attributes to higher precision types (at the cost of more memory) or lower precision types (to save memory) using the Attrib Cast SOP node.
您可以选择使用“属性创建”节点创建的属性的数值精度 ，和/或使用“属性转换 SOP”节点将属性转换为更高精度类型（以更多内存为代价）或更低精度类型（以节省内存）。

See Attrib Cast for information on the available storage types and limitations.
有关可用存储类型和限制的信息，请参见属性投射。

Indexing and limit variables
索引和限制变量

You may see the following “pseudo-attributes” in VEX snippets. They represent the number of the current element being processed (for example, the point number), and the total number of elements in the geometry/list. See indexing and limit variables in VEX snippets for more information.
您可能会在 VEX 片段中看到以下“伪属性”。它们表示正在处理的当前元素的编号（例如，点编号）以及几何/列表中元素的总数。有关详细信息，请参阅 VEX 代码段中的索引和限制变量 。

@elemnum, , , @ptnum@primnum@vtxnum
@elemnum，@ptnum@primnum@vtxnum

Represents the number of the current element when a VEX snippet is run.
表示运行 VEX 代码段时当前元素的编号。

@numelem, , , @numpt@numprim@numvtx
@numelem，@numpt@numvtx @numvtx

Represents the total number of elements in the geometry/list when a VEX snippet is run.
表示运行 VEX 片段时几何图形/列表中的元素总数。

Common attributes   共同属性

Each type of node will use certain attributes if they exist (or in some cases require them to exist), and may create/set attributes as part of their operation. See the documentation for individual nodes to see the attributes they use/set.
每种类型的节点将使用某些属性（如果它们存在）（或者在某些情况下要求它们存在），并且可以创建/设置属性作为其操作的一部分。请参阅各个节点的文档以查看它们使用/设置的属性。

The following lists a number of attributes that by convention are read/written by multiple node types.
下面列出了许多属性，按照约定，这些属性可由多个节点类型读取/写入。

Geometry attributes   几何体属性

P

 vector  向量

Point position. The viewport uses this to lay out the points of the model in 3D space. You can overwrite this attribute to move the point.
点的位置。视口使用此选项在 3D 空间中布置模型的点。可以覆盖此属性以移动点。

On point
对点

N

 vector  向量

Normal direction. You can overwrite this attribute to change the normal.
正常方向。可以覆盖此属性以更改法线。

v

 vector  向量

Velocity. The renderer uses this attribute to know where to add motion blur. This attribute is not computed automatically, but several nodes, especially particle DOPs, can set/use it. You can add velocity to points using the Trail SOP
速度渲染器使用该属性来知道在哪里添加运动模糊。此属性不会自动计算，但多个节点（尤其是粒子 DOP）可以设置/使用它。您可以使用 Trail SOP 为点添加速度.

id

 int

A unique element ID. This is not the same as the element number (for example, the point number). This is an attribute you can, for example, assign to points to keep track of them even if the point numbers change (which can happen if the number of points change). Particle DOPs often set/use this attribute.
唯一的元素 ID。这与元素编号（例如，点编号）不同。例如，您可以将此属性指定给点以跟踪这些点，即使点编号发生更改也是如此（如果点数发生更改，则会发生这种情况）。粒子 DOP 通常设置/使用此属性。

name

 string  字符串

Set this value on primitives, such as volumes or packed primitives, to find them in code by name. Some nodes set/read this attribute.
对基本体（如卷或压缩基本体）设置此值，以按名称在代码中查找它们。某些节点设置/读取此属性。

piece

 int

Nodes that break up geometry into pieces will often set this attribute so that you can tell which polygonal faces are part of the same piece. Faces in the same piece will share the same value in their attribute. Other nodes may use this attribute to operate on pieces.piece
将几何体分解为多个片段的节点通常会设置此属性，以便可以区分哪些多边形面属于同一片段。同一块中的面将在其属性中共享相同的值。其他节点可以使用此属性对片段进行操作。 件
Sizes and rotations   尺寸和旋转

pscale

 float  浮子

Uniform scaling factor. This is used in different ways in different places. For particle/point rendering, it controls the size of the particle/point (in world space units) at render time. For instancing, you can use it to uniformly scale the instanced geometry.
统一比例因子。这在不同的地方以不同的方式使用。对于粒子/点渲染，它控制渲染时粒子/点的大小（以世界空间单位表示）。对于实例化，可以使用它统一缩放实例化的几何体。

scale

 vector  向量

Whereas is a single uniform scaling factor in all axes, this attribute lets you scale non-uniformly along each axis separately. pscale
虽然所有轴中有一个统一的缩放因子，但此属性允许您分别沿每个轴进行非均匀沿着缩放。pscale

width

 float  浮子

When rendering open curves, sets the line width (in world space units) at render time. If this attribute does not exist, Mantra renders the open curve as a thin line instead of a ribbon with thickness.
渲染开放曲线时，在渲染时设置线宽（使用世界空间单位）。如果此属性不存在，Mantra 将开放曲线渲染为细线，而不是具有厚度的带状。

On point
对点

lod

 float  浮子

Level of detail. This may be used in instancing.
详细程度。这可以在实例中使用。

On detail, prim
在细节上，

spritescale

 vector  向量

When displaying particles using sprint images, this gives additional sprite scaling over .pscale
当使用 sprint 图像显示粒子时，这会提供额外的精灵缩放。pscale

Default (1, 1, 1) On point
默认 （1，1，1） 在点

spriterot

 float  浮子

When displaying particles using sprint images, this gives sprite rotation (around camera angle) in degrees.
当使用 sprint 图像显示粒子时，这将以度为单位提供子画面旋转（围绕相机角度）。

Default 0 On point
默认 0 点

Viewport display attributes
视口显示属性

gl_wireframe

 int

If this detail attribute is 1, the geometry always appears as wireframe in the viewport.
如果该细节属性为1，则几何体在视口中始终显示为线框。

If this detail attribute is -1, the geometry always appears as shaded in the viewport. For guide geometry, which are normally only drawn as wireframe, this allows them to also be drawn as shaded when using any of the shaded viewport modes.
如果该细节属性为-1，则几何体在视口中始终显示为着色。对于通常仅绘制为线框的导向几何体，这允许它们在使用任何着色视口模式时也绘制为着色。

Default 0 On detail
默认 0 详细信息

gl_shadeopencurves

 int

If this detail attribute is 1 and a attribute is present, curves will be drawn as ribbons and shaded.width
如果该细节属性为 1 且存在属性，则曲线将绘制为带状并着色。 宽度

Default 0 On detail
默认 0 详细信息

gl_lit

 int

If this detail attribute is 0, the geometry always appears without lighting. This is currently ignored for guide geometry.
如果此细节属性为0，则几何体始终显示为无照明。对于引导几何体，当前忽略此操作。

Default 1 On detail
默认值 1 详细信息

gl_showallpoints

 int

If this detail attribute is not 0, all points will be rendered as sprites, even if they are connected to geometry. Normally only unconnected points are rendered. This is currently ignored for guide geometry.
如果此细节属性不为0，则所有点都将渲染为子画面，即使它们连接到几何体。通常只渲染未连接的点。对于引导几何体，当前忽略此操作。

Default 0 On detail
默认 0 详细信息

gl_spherepoints

 int

If this detail attribute is not 0, unconnected points will be drawn as spheres rather than as the render properties or as sprites. can cause connected points to also be drawn this way.gl_showallpoints
如果此细节属性不为 0，则未连接的点将绘制为球体，而不是渲染属性或精灵。也可以使连接点以这种方式绘制。gl_showallpoints

Default 0 On detail
默认 0 详细信息

gl_xray

 int

If this detail attribute is not 0, the geometry will be drawn in X-Ray mode (visible even when it is hidden behind other geometry).
如果此细节属性不为 0，则几何体将在 X 射线模式下绘制（即使隐藏在其他几何体后面也可见）。

Default 0 On detail
默认 0 详细信息

vm_cuspangle

 float  浮子

Controls the cusp angle used for generating normals when the geometry does not have any normals. 180 will produce entirely smooth point normals.
当几何体没有任何法线时，控制用于生成法线的尖点角度。180将产生完全平滑的点法线。

Default 60 On detail
默认 60 详细信息

gl_spritetex

 string  字符串

Specifies a texture for sprites. This is only valid on unconnected points, or if is 1.gl_showallpoints
指定子画面的纹理。这仅对未连接的点有效，或者如果为 1。gl_showallpoints

On point
对点

gl_spriteblend

 int

If this attribute is set to 1, turns on blending when drawing sprites. When set to 0, no depth sorting or blending occurs, greatly increasing the draw performance of sprites. Turning off blending is good for opaque sprites like vellum grains.
如果该属性设置为1，则在绘制精灵时启用混合。当设置为0时，不会发生深度排序或混合，从而大大提高子画面的绘制性能。关闭混合对不透明的精灵（如牛皮纸颗粒）有好处。

Default 1 On detail
默认值 1 详细信息

gl_spritecutoff

 float  浮子

When is 0, discard all pixels with an alpha value less than this cutoff value. 0 discards no pixels, while 1 only keeps fully opaque pixels. Values between 0.5-0.75 are generally good for opaque sprites with antialiased edges.gl_spriteblend
如果为 0，则丢弃 Alpha 值小于此截止值的所有像素。0 不丢弃任何像素，而 1 仅保留完全不透明的像素。值在 0.5-0.75 之间通常适用于具有抗锯齿边缘的不透明子画面。gl_spriteblend

Default 0 On detail
默认 0 详细信息

Viewport volume display attributes
视口体积显示属性

The following detail attributes control how the viewport renders volume primitives. The viewport can display these primitives as fog, height fields, or isosurfaces (signed distance fields). To query this property, you can read the primitive intrinsic attribute. The detail attributes listed in this section apply to fog volumes, and some of them also affect the viewport display of height fields.volumevisualmode
以下细节属性控制视口渲染体积基本体的方式。视口可以将这些基元显示为雾、高度场或等值面（带符号的距离场）。若要查询此属性，可以读取基元内部属性。本部分中列出的细节属性适用于雾体积，其中一些属性还影响高度场的视口显示。 体积视觉模式

A volume visualization set can have the following 4 components.
体积可视化套件可包含以下4个组件。

density

For fog, this component contains the optical thickness of the smoke. With height fields, this main volume should store the elevation at each voxel.
对于雾，此分量包含烟的光学厚度。对于高度字段，此主体积应存储每个体素的高程。

cd

The color field. This component can be used with both fog (to color the smoke) and height fields (to texture the terrain).
色场。此组件可与雾（为烟雾着色）和高度字段（为地形纹理）一起使用。

emit

With fog, this component contains the intensity of emission (or internal glowing). For height fields, this component acts like a visualization stencil - the viewport only draws parts of the height field where the value is at least .emit0.5
对于雾，该组件包含发射（或内部发光）的强度。对于高度字段，此组件的作用类似于可视化模具-视口仅绘制值至少为的高度字段部分。 发射 0.5

emitcd

This component can be used with fog volumes to color the internal emission.
该组件可以与雾体积一起使用，以对内部发射着色。

The in the attribute names in this section can be one of the above 4 strings. You can use the *Volume Visualization SOP to set or modify these attributes.
本节中属性名称中的可以是上述 4 个字符串之一。您可以使用 *Volume Visualization SOP 来设置或修改这些属性。

volvis_*field

 string  字符串

Name of the volume containing data for the respective component.
包含相应组件数据的卷的名称。

volvis_*range

 vector2  向量2

Range of volume values that gets remapped to the 0..1 range.
重新映射到0的体积值范围。1范围。

Default [0, 1]
默认值 [0，1]

volvis_*ramp

 string  字符串

Contains a string representation of the ramp that remaps the respective volume values. If no string is present, no ramp is used to remap the values.
包含渐变的字符串表示，该表示重新映射相应的体积值。如果不存在字符串，则不使用渐变来重新映射值。

volvis_*rampperiodic

 int

Flags how the ramp is applied to the remapped volume values. When set to , the ramp is evaluated at the modulus of the volume’s value with . This can be useful to create a checkerboard or striped effect to better see large ranges of values.11
标记渐变如何应用于重新映射的体积值。设置为时，渐变将以体积值的模数计算。这对于创建棋盘或条纹效果以更好地查看大范围的值非常有用。11

volvis_maxres

 int

Limits the visualization resolution of volumes. When set to a positive value and the volumes are high resolution, the volumes are resampled to this size before rendering.
限制体积的可视化分辨率。如果设置为正值且体积为高分辨率，则在渲染之前将体积重新采样为该大小。

Default -1
默认值-1

volvis_emitscale

 float  浮子

Acts as a multiplier for emission intensity. Higher values increase the brightness of the internal glow (for example, the flames in a fire).
作为发射强度的乘数。较高的值会增加内部辉光的亮度（例如，火中的火焰）。

Default 0
默认值 0

volvis_shadowscale

 float  浮子

Controls the intensity of self-shadowing from all light sources. Larger values result in darker self-shadows.
控制来自所有光源的自阴影强度。值越大，自阴影越暗。

Default 1
默认 1

volvis_ambientshadows

 float  浮子

Controls the intensity of self-shadowing from ambient light sources. Note that the default headlight is treated as an ambient source for fog volumes.
控制来自环境光源的自阴影的强度。请注意，默认前照灯被视为雾体积的环境光源。

The default value of this attribute is set by Ambient Occlusion under the viewport display options.
此属性的默认值由 “环境光遮挡 ”在 视口显示选项 。

volvis_ambientmapsize

 float  浮子

Controls the size of the occlusion map texture when shading for ambient light sources. Larger values (up to 1) are slower to shade, but produce higher quality results.
控制对环境光源进行着色时遮挡贴图纹理的大小。较大的值（最大为1）着色速度较慢，但会产生更高质量的结果。

Default 0.5
默认值 0.5

volvis_ambientsteprate

 float  浮子

Specifies how often the density texture is sampled when calculating self-shadowing from ambient light sources. Smaller values (down to 1) are slower to shade, but produce higher quality results.
指定从环境光源计算自阴影时，密度纹理的采样频率。较小的值（小至1）着色较慢，但会产生较高质量的结果。

Default 4
默认 4

volvis_shadowcolor

 vector  向量

Controls the color of the shadows cast by the smoke. The complements of these values act like additional density multipliers for the light of each color (red, green, or blue).
控制烟投射的阴影的颜色。这些值的补集就像每种颜色（红色、绿色或蓝色）的灯光的附加密度倍增器。

Default [1, 1, 1]
默认值 [1，1，1]

The viewport can additionally approximate scattering of light within fog volumes. This feature is experimental and may be changed or removed in future versions of Houdini.
此外，视口还可以近似雾体积内的灯光散射。此功能是实验性的，可能会在未来的 Houdini 版本中更改或删除。

volvis_extinctionratio

 float  浮子

Specifies the proportion of light that is absorbed by the volume (as opposed to being scattered out). A value of 1 signals that no scattering takes place. A value of 0 suggests that all light that interacts with the smoke is scattered.
指定被体积吸收的光的比例（与散射的光相对）。值为1表示不发生散射。值为0表示与烟雾相互作用的所有灯光都被散射。

Default 1
默认 1

volvis_scatteringiter

 int

Scattering is approximated by an iterative process, and this attribute stores the number of refinement iterations that are performed. Larger values produce more accurate results, but take longer to compute.
散射由迭代过程近似，该属性存储执行的细化迭代次数。值越大，结果越准确，但计算时间越长。

Default 25
默认值 25

When working with fog volumes, you can force the viewport to instead draw its motion vectors or normals. This behavior is also controlled through detail attributes.
使用雾体积时，可以强制视口改为绘制其运动向量或法线。此行为也通过详图属性进行控制。

volvis_motionvec

 int

The viewport will draw screen-space motion vectors for the fog when this attribute is non-zero. The vector volumes will be used to read the velocities.vel
当该属性不为零时，视口将为雾绘制屏幕空间运动向量。矢量体积将用于读取速度。vel

Default 0
默认值 0

volvis_normals

 int

The viewport will draw screen-space normals for the fog when this attribute is non-zero. If both and are non-zero, the viewport will draw the normals.volvis_normalsvolvis_motionvec
当该属性非零时，视口将为雾绘制屏幕空间法线。如果和都不为零，则视口将绘制法线。volvis_normalsvolvis_motionvec

Default 0
默认值 0

Particle attributes   粒子属性

force

 vector  向量

The attribute on the current point. This is set/used by some particle DOPs. It represents a change to the particle’s position computed by adding up all the forces acting on the particle.force
当前点上的属性。这由某些粒子 DOP 设置/使用。它表示通过将作用在粒子上的所有力相加而计算出的粒子位置的变化。 力

rest

 vector  向量

Conventional name for an attribute containing each point’s rest position, used by various nodes. Some shaders can use this rather than , so procedural textures will stick even if you deform your geometry.P
包含每个点的静止位置的属性的常规名称，由各种节点使用。某些着色器可以使用此选项而不是，因此即使变形几何体，程序纹理也会保持不变。P

On point
对点

torque

 vector  向量

The attribute on the current point. This is set/used by the torqueTorque DOP to spin particles.
当前点上的属性。这由扭矩 DOP 设置/使用以旋转粒子。

up

 vector  向量

Represents the up vector of a particle’s local space. This is used for instancing geometry onto a point. You can overwrite this attribute to change the particle’s orientation.
表示粒子局部空间的上方向向量。这用于将几何体实例化到点上。可以覆盖该属性以更改粒子的方向。

accel

 vector  向量

Obsolete, used by old POPs. The new DOP particle nodes use the attribute instead.force
很明显，被老的 POP 使用。新的 DOP 粒子节点将使用该属性。 力

backtrack

 vector4  矢量4

Obsolete. Used by old POPs to store the particle’s previous position.
不明显花瓣由旧 POP 用于存储粒子的先前位置。

orient

 vector4  矢量4

Quaternion orientation of a particle. Allows fully specifying rotation, whereas only orients along a single axis. If this exists, it is used for instancing geometry onto a point.up
粒子的四元数方向。允许完全指定旋转，而仅沿沿着单个轴定向。如果存在，则用于将几何体实例化到点上。 起来

rot

 vector4  矢量4

An additional offset-quaternion applied after all other attributes, used when instancing geometry onto a point.
在所有其他属性之后应用的附加偏移四元数，在将几何体实例化到点上时使用。

nextid

 int

Detail attribute storing the largest particle ID, allowing Houdini to create new particle ids efficiently.
细节属性存储最大的粒子 ID，允许 Houdini 有效地创建新的粒子 ID。

pstate

 int

A bit field encoding different pieces of information about a particle’s state (for example, whether it is alive, whether it is stopped, whether it collided in the previous frame, etc). Various particle DOPs read and write this attribute.
一个比特字段，用于编码关于粒子状态的不同信息（例如，它是否存活、是否停止、是否在前一帧中发生碰撞等）。各种粒子 DOP 读取和写入此属性。

The value is the sum of the following flags:pstate
该值是以下标志的总和：pstate

0x01

Is a “primary” particle (not birthed from an existing particle).
是一个“主要”粒子（不是从现有粒子产生的）。

0x02

Will die before the next frame.
会在下一帧前死去。

0x04

Stopped.  停止.

0x08

Has collided.  已经相撞。

0x10

Stuck to static or moving geometry.
停留在静态或动态几何体上。

0x20

Is associated with a rigid body dynamic simulation.
与刚体动力学模拟关联。

0x40

Active.  活跃

0x80

Motion is overridden by a CHOP.
运动被 CHOP 覆盖。

Shader overrides   着色器覆盖

Most shaders will use the override attributes to change how elements with these attributes are shaded.
大多数着色器将使用覆盖属性来更改具有这些属性的元素的着色方式。

Cd

 vector  向量

Diffuse color override. The viewport uses this to color OpenGL geometry.
漫反射颜色替代。视口使用此选项为 OpenGL 几何体着色。

Alpha

 float  浮子

Alpha transparency override. The viewport uses this to set the alpha of OpenGL geometry.
阿尔法透明度覆盖。视口使用此设置 OpenGL 几何体的 alpha。

Cs

 vector  向量

Specular color override.
镜面反射颜色覆盖。

Cr

 vector  向量

Reflect color override.  反射颜色替代。

Ct

 vector  向量

Transmit color override.
传输颜色覆盖。

Ce

 vector  向量

Emission color override.
发射颜色替代。

rough

 float  浮子

Roughness override.  粗糙度超驰。

fresnel

 float  浮子

Fresnel coefficient override.
菲涅尔系数超驰。

shadow

 float  浮子

Shadow intensity override.
阴影强度覆盖。

sbias

 float  浮子

Shadow bias override.  暗影偏移解除。

Rendering attributes   渲染属性

uv

 vector  向量

The UV coordinates of the point/vertex. The first two elements of this vector contain the current U and V coordinates. Note that is Houdini’s conventional attribute name for storing texture coordinates. You can store texture coordinates in other attributes and have multiple UV layouts on the same geometry. Most texture-related nodes have a field to let you specify the name of the UV attribute to use.uv
点/顶点的 UV 坐标。该向量的前两个元素包含当前 U 和 V 坐标。请注意，这是 Houdini 用于存储纹理坐标的传统属性名称。可以将纹理坐标存储在其他属性中，并在同一几何体上具有多个 UV 布局。大多数与纹理相关的节点都有一个字段，用于指定要使用的 UV 属性的名称。UV

On point, vertex
在点上 ，顶点

material

 string  字符串

The node path to the material to use to shade this primitive. Overrides the object’s material.
用于着色此基本体的材质的节点路径。替代对象的材质。

instance

 string  字符串

The attribute on the current point, containing a path to the geometry instanced on the point. This can be a file path to a geometry file, or an path to a geometry object or node. You can overwrite this attribute to change the instanced geometry.instanceop:
当前点上的属性，包含指向该点上实例化的几何体的路径。这可以是几何文件的文件路径，也可以是几何对象或节点的路径。可以覆盖此属性以更改实例化几何体。 实例操作：

On detail, prim
在细节上，

rishade

 string  字符串

Detail/primitive. The name of a RenderMan shader.
细节/原始。RenderMan 着色器的名称。

On detail, prim
在细节上，

See also   另见

Geometry   几何

Understanding   理解

Modeling   建模

Terrain   地形

Fracturing   压裂

Clouds   云

Next steps   后续步骤

Guru level   宗师级