The name of the new parameter, both in the VEX function declaration, the definition of any OP type that uses the VOPNET, and the VOP tile’s output. If a parameter by this name already exists, this operator will reference it and will disable most of of its own fields, such as the Parameter Type and Parameter Label.

The name must not be a reserved keyword.

The optional prefix to prepend to the parameter name. The prefix changes the final name of the new parameter, both in the VEX function declaration, the definition of any OP type that uses the VOPNET, and the VOP tile’s output.

The optional postfix to append to the parameter name. The postfix changes the final name of the new parameter, both in the VEX function declaration, the definition of any OP type that uses the VOPNET, and the VOP tile’s output.

A human-readable label for this parameter. Appears in the owner node’s parameters and the tooltip when the user hovers over the output on the VOP tile.

Toggles the display of the parameter label in the owner node’s parameters.

Specifies the VEX data type of the new parameter. It can also specify how the parameter should be represented in an OP dialog. For example, a VEX vector can be viewed as 3 float values or as a color value.

Depending on the parameter type selected, it represents the default value of the parameter in the VEX function and in the OP type that uses this VOP network.

Brief description of the parameter. The comment is included after the parameter declaration in the generated code.

When several Parameter VOPs have the same Parameter Name, only one of the nodes is used to control the attributes of the parameter. 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.

When several Parameter or Bind VOPs have the same Parameter Name, some other node will determine export context. However, it may be desirable to have each Parameter VOP exporting in a different context. In such cases, setting this parameter will enable this node to specify own export context, independent of the primary definer node.

If true, the VEX function parameter is checked to see if it is bound to an attribute in the current VEX context (e.g. point color). If not bound, the input value is is assigned to the VEX parameter. In a Surface VOP context, a VEX parameter is bound if the geometry being shaded has an attribute with the VEX parameter name.

If true, the shader node parameter defined by this Parameter VOP will also have a corresponding input connector, providing such shader nodes can have input and output connectors.

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. In SOP and POP networks, the exported parameters create new geometry attributes.

The context or contexts that the parameter is exported to. Use whitespace characters as separators when specifying multiple contexts.

If the parameter type is String or Integer, then you can provide a menu of choices instead of a string entry field or an integer slider.

A list of pairs of strings. The first string in each pair is the parameter value if that menu item is chosen. The second string is the label that appears in the dialog for that menu item.

The strings are separated by spaces. If you want a value or label to contain a space, surround the item with double quotes.

A script that populates the generated menu. You can write the script in either Hscript or Python. We highly recommend using Python.

A Python script should generate a list (or tuple) of strings where the odd items are values and the even items are labels, for example:

["10", "Light", "50", "Medium", "100", "Heavy"]

Houdini handles the Python script in an odd way: if the script field contains a single line, Houdini treats it as an expression and expects it to evaluate to a list. If it has multiple lines, Houdini treats it as a function body and it must end with a return statement:

result = []
for input_node in hou.pwd().inputs():
    result += [input_node.path(), input_node.name()]
return result

For Hscript, the script should print a space-separated list of the form:

echo "token1" "Label 1" "token2" "Label 2" ...

The language used by the script populating the menu.

Do not show the parameter in the shader’s parameter interface. The parameter still exists and will be used to generate shader strings.