Houdini 16.5 Nodes VOP nodes

Shading Layer Parameter VOP node

Creates a parameter to appear in the signature of the VEX function defined by the VOP network (VOPNET).

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This operator creates a parameter to appear in the signature of the VEX function defined by the VOP network (VOPNET). The new parameter is named according to the chosen geometry attribute and the specified layer.

Unlike the Parameter operator, which creates parameters of any name and type, Shading Layer computes the parameter name from the name of the geometry attribute and the specified layer. For example, choosing UV Coordinates from the attribute menu will generate uv, uv2, uv3 when the layer is 1 and respectively 2 and 3. The parameter type matches the type of the selected geometry attribute.

This operator always checks if the geometry attribute is bound and, if so, assigns its value to the new parameter. Thus, the new parameter will be hidden in the operator type defined by the VOP network.

One of the most common uses of this operator is the creation of layered textures, which requires different sets of texture coordinates for each Texture operator. To accomplish this task, choose UV Coordinates from this operator’s attribute menu and set the appropriate layer. Pipe the uv output into a Vector To Float operator to extract the s and t as individual float values, then wire s and t into the Texture operator. Repeat this operation for all the layers, then add or multiply the all Texture outputs using the Add or Multiply operator respectively.

Parameters

Geometry Attribute

The attribute to be searched for in the given layer. The following attributes are available in this operator:

Label          | Name  | Type     | Default If Not Bound
---------------+-------+----------+---------------------------
UV Coordinates | uv    | 3 floats | { global s, global t, .5 }
RGB Color      | Cd    | 3 floats | { 1, 1, 1} (i.e. white)
Alpha          | Alpha | 1 float  | 1          (i.e. opaque)

Geometry attributes are created in the Geometry module using a variety of SOP operators such as: AttribCreate, Attribute, Point, UV Project, UV Texture, UV Unwrap, etc.

Use This Node to Set Parameter Attributes

When several Shading Layer VOPs have the same Geometry Attribute chosen, only one of the nodes is used to control the settings of the attribute. Houdini decides which node to use for this by searching all the nodes according to the user defined order, then traversing inside subnets. If none of them have this parameter turned on, the first one found is used to set the parameter attributes. If one or more do have this option turned on, the first one with this option is used, even if another node (with this option turned off) is found first.

Attribute Layer

Attribute layer where to search for the geo attribute. Layer 1 is the default layer. Attributes in this layer do not have a suffix. Layers are created in the Geometry module using the Layer SOP.

Export

Specifies whether the new parameter can be exported to other contexts (written to as well as read from). If set to Always or When Input is Connected, this operator gets an input. The value wired into this input is then assigned to the exported parameter. In a Surface network, exported parameters can be used to create deep rasters.

Never

The parameter will not be exported.

Always

The parameter will be exported.

When Input is Connected

The parameter will only be exported if the node’s input is ultimately connected to another VOP.

Inputs

Export Value

The value assigned to the new parameter if the Export Parameter toggle is checked.

Outputs

Output Parameter

The value of this VEX function parameter.

Is Parameter Bound

True is the new parameter is bound to an attribute.

See also

VOP nodes