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  • houdini.label (STRING): The UI name of the parameter. Defaults to an automatically capitalized version of the Arnold parameter name.
  • (STRING): The tooltip text.
  • houdini.type(STRING): A subtype for some parameters:
    • "file:image": Add an image file requester button for a string parameter.
    • "file:*.toto": Add a file requester with "*.toto" as file filter.
    • "menu:<type>:<language>": Add a menu to the parameter, of type {replace|toggle|append|wild|exclusive|single}, whose items are taken from the metadata (menu), or generated with a Python (python) or HScript (hscript) script {menu|python|hscript}."
    • "opfilter[:<filter>]": The parameter is an operator path, with an optional filter specification. For example, "opfilter:!!OBJ/CAMERA!!" will filter out everything but cameras. See PRM/PRM_SpareData.h for a complete list of valid filter values.

  • houdini.disable_whenhoudini.hide_when (STRING): Parameter expression to specify a condition under which a parameter is hidden or disabled (grayed out). Hiding a parameter will not hide its corresponding input. The expression syntax is described here:
  • houdini.invisible (BOOL): Parameter will be created, but its UI will not be visible.
  • houdini.no_menu_caps (BOOL): Do not auto-capitalize menu entries.
  • linkable (BOOL): This parameter cannot vary per sample and thus no input should be created for it.
  • houdini.no_input (BOOL): Do not create a corresponding input for the parameter. Use this metadata only in case you need to override the "linkable" metadata.
  • houdini.skip (BOOL): Skip parameter altogether, it will not appear in control nor inputs.
  • minmaxsoftminsoftmax (FLOAT): (hard, soft) x (minimum, maximum) values for the parameter. Note that Houdini only supports a min and a max, optionally qualified as hard or soft, so these values will be mapped to a PRM_Range in the getRange() helper function.
  • (STRING): A user defined menu to be used for drop-down menus, choice-lists, etc. The items are semi-colon separated token-label pairs, eg. "one;Item number 1;two;Item number 2".
  • houdini.menu_script (STRING): An HScript or Python script to generate token-label pair representing menu items. Cf.
  • houdini.expression (STRING): A default expression to set on the parameter. If prefixed with "python:", the expression will be treated as Python code, otherwise it will be treated as old expression script.

  • houdini.array_token (STRING): A token string for array parameters that must contain "%s" for the container token and "%i" for the element index, in this order.

  • houdini.join_next (BOOL): The next parameter will be on the same line.

  • houdini.no_label (BOOL): Do not display the label.

  • houdini.callback (STRING): A callback script called when the parameter value changes. The script can be prefixed with "hscript:" or "python:" to specity the language. Without a prefix, the script is considered to be written in HScript.


The following plugins are available for HtoA: 

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