parm_set
Destructive
Write Houdini node parameter values, press buttons, set expressions or keyframes, and snapshot or restore settings, with reasons when a write fails.
Instructions
Write parameter values, or press a button. One write, or a list in one undo group.
Use it after node_inspect has confirmed the parameter name and the type.
A write can be accepted and change nothing, and Houdini says nothing. This
tool looks for all six causes and names the one it found:
- the parameter carries an expression, which still decides the value;
- the parameter is animated, so the value became a new key;
- the parameter is locked;
- another parameter disables or hides it, so the cook does not read it;
- a strict range clamped the value;
- the parameter reads another node through a channel reference, so the
write would change that other node. It is refused; give
`follow_reference=true` to write the node at the other end.
Read `warnings` and `not_applied` in the result before you report success.
mode, and the arguments that each mode reads:
"value" — path, parm, value. Or path and parameters, a
dictionary of several names and values. A menu
takes its token, for example "custom". A
bit-field menu takes a token or a list of them.
"press" — path, parm: press a button, for example Save to
Disk on a File Cache, Reload on a File SOP, or
Resimulate on a solver. The result holds the errors
and the warnings of the node after the press,
because work that a button starts fails later and
in silence.
"expression" — path, parm, expression, language ("hscript" or
"python").
"keyframe" — path, parm, frame, value.
"keyframes" — path, parm, keyframes: a list of {frame, value}.
"delete_keyframe" — path, parm, frame.
"revert" — path, parm: back to the default, and the
expression goes away.
"lock" — path, parm, locked.
"link" — src_path, src_parm, path, parm: the parameter at
path follows the one at src_path.
"spare" — path, parameters: a list of controls to add, each
{name, label, type, default, min, max, strict,
help, value, expression, items}. type is "float",
"int", "vector", "toggle", "string", "menu" (with
items), "ramp" or "color_ramp" (default: a list of
[position, value]). One control can also come as
name, label, parm_type, default, expression.
On a wrangle it first does what the Create
Parameters button does, a parameter for each ch()
call, and puts every control in that folder above
the code. Use it instead of numbers typed into VEX:
the user tunes these. A control that exists is
replaced in place, so a second call is safe.
"render_settings" — path, settings for a ROP node.
"chop_export" — chop_path, channel_name, path, parm.
"snapshot" — name, paths: save every parameter of these nodes,
with expressions, keys and the bypass flag, to the
record `name` on disk. "/obj/geo1/*" names every
node in a network. It overwrites a record of the
same name.
"restore" — name: put the record back, and list what changed.
`paths` limits it to some of the nodes.
"diff" — name: list how the scene differs from the record.
Changes nothing.
In a sweep, restore before each variant, not once
at the end: a variant that does not name a
parameter keeps the value of the one before.
Returns JSON with the value before, the value after, and a reason when the
write did not take.
Input Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| mode | No | One of "value", "press", "expression", "keyframe", "keyframes", "delete_keyframe", "revert", "lock", "link", "spare", "render_settings", "chop_export", "snapshot", "restore", "diff". | value |
| name | No | spare: the name of one control. snapshot, restore, diff: the record on disk. | |
| parm | No | The parameter name, for example "tx" or "divsize". | |
| path | No | The node that holds the parameter. | |
| frame | No | keyframe, delete_keyframe: the frame of the key. | |
| items | No | A list of writes, each a dictionary with the keys of one call. An argument outside items is the default for each one. | |
| label | No | spare: the label of one control. | |
| paths | No | snapshot: the nodes to save; "/obj/geo1/*" names every node in a network. restore: put back only these nodes. | |
| value | No | value, keyframe: the value to write. A menu takes its token. | |
| locked | No | lock: true locks the parameter, false unlocks it. | |
| default | No | spare: the default of one control. | |
| language | No | expression: "hscript" or "python". | hscript |
| settings | No | render_settings: the ROP parameters to write, by name. | |
| src_parm | No | link: the parameter to follow. | |
| src_path | No | link: the node to follow. | |
| chop_path | No | chop_export: the CHOP node. | |
| keyframes | No | keyframes: a list of {frame, value}. | |
| parm_type | No | spare: the type of one control, for example "float" or "toggle". | |
| expression | No | expression: the expression text. | |
| parameters | No | value: several names and values in one write, as a dictionary. spare: the list of controls to add. | |
| channel_name | No | chop_export: the channel that drives the parameter. | |
| follow_reference | No | Write the node at the other end of a channel reference. Without it, a write through a reference is refused. |
Output Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |