Tool parameters in Python: read and set the values of a tool

List the controls of an open tool, read and change their values and press its buttons from Python

Updated over 3 days ago

6 min read

Overview

When a tool window is open, its buttons, check boxes, number fields and drop-down lists are available to Python. A script can list them, read their values, change them and press buttons, exactly as you do in the window. This article uses the Mesh Healer tool (Mesh Repair › Mesh Healer) as the example.

Run the scripts in the Python window (Home › Python) with a mesh selected in the scene. How to open tabs and tools from a script is explained in Navigating MeshInspector’s UI Tree Programmatically.

Use the window name in the path

The parameters of a tool are inside the entry named after its window, the title shown at the top of the tool window. This is not always the name of the tool button in Ribbon: the button ['Ribbon', 'Object Section'] opens a window titled Section, so its parameters are under ['Section', ...], and the button ['Ribbon', 'Decimate Mesh'] opens the Simplify window. A wrong name stops the script with the error "No such entry", which lists the names that exist.

Listing Tool Parameters

Open the tool and list everything in its window with uiListEntries():

from meshlib import mrviewerpy as mv

# Open the Mesh Repair tab and the Mesh Healer tool
mv.uiPressButton(['RibbonTabs', 'Mesh Repair'])
mv.Viewer().skipFrames(1)
mv.uiPressButton(['Ribbon', 'Mesh Healer'])
mv.Viewer().skipFrames(1)

# List all controls inside the tool window
for entry in mv.uiListEntries(['Mesh Healer']):
    print(entry.name, entry.type)

Example output in MeshInspector 2.5.9 (Mesh Healer opens in the Local Repair mode):

##Auto Repair UiEntryType.button
##Local Repair UiEntryType.button
Disconnected Parts UiEntryType.valueUint
Flipped Normals UiEntryType.valueUint
Holes UiEntryType.valueUint
Repair Resolution UiEntryType.valueReal
Repair Selected UiEntryType.button
Restart on Mesh Selection Change UiEntryType.valueUint
Save Selection on Exit UiEntryType.valueUint
Self-Intersections UiEntryType.valueUint
Show Deviation Map UiEntryType.valueUint
Small Tunnels UiEntryType.valueUint
Thin Walls UiEntryType.valueUint
Undercuts UiEntryType.valueUint
Zero-Area Triangles UiEntryType.valueUint

The type tells you which function reads and writes the entry: button is pressed, valueReal is a number with a fraction, valueInt and valueUint are whole numbers (check boxes are valueUint with the values 0 and 1), valueString is text or a drop-down list.

Reading Parameter Values

Each value type has its own reading function. For a number field such as Repair Resolution use uiReadValueReal():

from meshlib import mrviewerpy as mv

val = mv.uiReadValueReal(['Mesh Healer', 'Repair Resolution'])
print("Current value:", val.value, "| Range:", val.min, "-", val.max)

Example output for a small test mesh (the value depends on the size of the mesh):

Current value: 0.004240000154823065 | Range: 0.001154000055976212 - 9.15999984741211

The result has the current value and the limits min and max of the field.

Changing Parameter Values

One function, uiWriteValue(), writes every type of value. It picks the type from the Python value you pass, so write a real number (0.5, 1.0) into a valueReal field: a whole number such as 1 does not change a real-number field. This script halves Repair Resolution and stays inside the allowed range:

from meshlib import mrviewerpy as mv

val = mv.uiReadValueReal(['Mesh Healer', 'Repair Resolution'])
new_val = max(val.min, min(val.max, val.value * 0.5))
mv.uiWriteValue(['Mesh Healer', 'Repair Resolution'], new_val)
mv.Viewer().skipFrames(1)

updated = mv.uiReadValueReal(['Mesh Healer', 'Repair Resolution']).value
print("Updated value:", updated)

Example output:

Updated value: 0.0021200000774115324

Keep the new value within min and max. Read the value back, as in the script, to make sure the change was applied.

Working with Different Value Types

Field	Read with	Write with
Real number	`uiReadValueReal()`	`uiWriteValue()` with a float
Whole number	`uiReadValueInt()`	`uiWriteValue()` with an int
Unsigned number	`uiReadValueUint()`	`uiWriteValue()` with an int
Check box	`uiReadValueUint()`	`uiWriteValue()` with `0` or `1`
Text, list	`uiReadValueString()`	`uiWriteValue()` with a string

All functions take the path of the entry; uiWriteValue() takes the new value as the second argument:

val = mv.uiReadValueReal(['Mesh Healer', 'Repair Resolution'])
mv.uiWriteValue(['Mesh Healer', 'Repair Resolution'], val.value * 0.5)

For a check box, 0 means cleared and 1 means checked. Mesh Healer remembers its check boxes when you close and open it again, so a script should set the ones it relies on. This line clears the Holes check box, so Repair Selected leaves holes alone:

mv.uiWriteValue(['Mesh Healer', 'Holes'], 0)

For a text field or a drop-down list, uiReadValueString() returns the value and, for a list, the allowed values; write one of them.

Triggering Actions (Buttons)

Buttons are pressed with uiPressButton(). In the Local Repair mode of Mesh Healer, Repair Selected fixes the problem types whose check boxes are checked. Mesh Healer also remembers its mode, so press the ##Local Repair button first: in the Auto Repair mode there is no Repair Selected.

from meshlib import mrviewerpy as mv

mv.uiPressButton(['Mesh Healer', '##Local Repair'])
mv.uiPressButton(['Mesh Healer', 'Repair Selected'])
mv.Viewer().skipFrames(1)
print("Action 'Repair Selected' triggered.")

This does the same as clicking the button in the window. A button that cannot be used now (for example, Repair Selected with no check box checked) is not pressed: the script continues without an error and only the MeshInspector log gets a warning. Check the status of the button before you rely on it:

from meshlib import mrviewerpy as mv

for entry in mv.uiListEntries(['Mesh Healer']):
    if entry.name == 'Repair Selected':
        print(entry.name, '->', entry.status)

The status is available, or the reason why the button is unavailable.

Local Repair and Auto Repair. Mesh Healer has two modes, switched with the buttons ##Local Repair and ##Auto Repair of its window. Repair Resolution belongs to both. The problem check boxes and Repair Selected are in Local Repair; Auto Repair rebuilds the whole model with the Auto Rebuild Model button and has its own settings. After you switch the mode, list the window again to see its controls.

Waiting for Long Operations

Inspection and repair can take a while. While an operation runs, the top of the UI tree has an entry named ProgressBar. This function waits until it disappears:

import time
from meshlib import mrviewerpy as mv

def wait_progress_bar():
    mv.Viewer().skipFrames(2)
    while any(e.name == "ProgressBar" for e in mv.uiListEntries([])):
        time.sleep(0.2)

Call it after you open a tool that inspects the mesh (Mesh Healer does) and after you press a button that starts a calculation.

Name Matching and Best Practices

List before you use. Get the names with uiListEntries(): the names are exact, including case, spaces and hyphens.
Use the window title for parameters and the internal tool name for Ribbon buttons.
Read before you write, so the new value stays within min and max.
Pass the right Python type to uiWriteValue(): a float for real numbers, an int for whole numbers and check boxes, a string for text.
Wait for long operations before you read results or press the next button.

Example: Full Workflow

This script opens Mesh Healer for the selected mesh, halves Repair Resolution, checks Holes, runs Repair Selected and prints the number of holes before and after:

import time
from meshlib import mrviewerpy as mv

def wait_progress_bar():
    mv.Viewer().skipFrames(2)
    while any(e.name == "ProgressBar" for e in mv.uiListEntries([])):
        time.sleep(0.2)

holes_before = mv.getSelectedMeshes()[0].topology.findNumHoles()

# Open the Mesh Repair tab and the Mesh Healer tool
mv.uiPressButton(['RibbonTabs', 'Mesh Repair'])
mv.uiPressButton(['Ribbon', 'Mesh Healer'])
wait_progress_bar()

# Switch to Local Repair (Mesh Healer opens in the mode it was closed in)
mv.uiPressButton(['Mesh Healer', '##Local Repair'])

# Adjust the parameters: halve Repair Resolution, make sure Holes is checked
val = mv.uiReadValueReal(['Mesh Healer', 'Repair Resolution'])
mv.uiWriteValue(['Mesh Healer', 'Repair Resolution'], max(val.min, val.value * 0.5))
mv.uiWriteValue(['Mesh Healer', 'Holes'], 1)
mv.Viewer().skipFrames(1)

# Run the repair and wait for it
mv.uiPressButton(['Mesh Healer', 'Repair Selected'])
wait_progress_bar()

holes_after = mv.getSelectedMeshes()[0].topology.findNumHoles()
print("Holes before:", holes_before, "after:", holes_after)

Example output for a test mesh with two small holes:

Holes before: 2 after: 0

Cookie	Duration	Description
meshinspector_cookie_consent	1 year	Stores your choices and a random consent ID used only to prove your consent.
__cf_bm	30 minutes	Set by Cloudflare on HubSpot and LinkedIn domains to tell people from bots, for example when the HubSpot forms on our contact and reseller pages load.
_GRECAPTCHA	Up to 6 months	Strictly necessary for the security of our contact form: Google reCAPTCHA sets it on google.com for its risk analysis, which protects the form against spam and abuse.
rc::a, rc::d-* (local storage)	Until cleared	Strictly necessary for the security of our contact form: Google reCAPTCHA stores them on google.com, in its frame inside the form, to tell people from bots.
rc::c (session storage)	Session	Strictly necessary for the security of our contact form: Google reCAPTCHA stores it on google.com for the current visit, to tell people from bots.

Cookie	Duration	Description
_ga	2 years	Google Analytics: distinguishes visitors.
_ga_SCHM0KJKPH	2 years	Google Analytics: keeps the session state.
_clck	1 year	Microsoft Clarity: keeps the Clarity user ID and preferences.
_clsk	1 day	Microsoft Clarity: connects several page views into one session.
_cltk (session storage)	Session	Microsoft Clarity: identifies the browser tab.
__hstc	6 months	HubSpot: main analytics cookie with visitor and session data.
hubspotutk	6 months	HubSpot: visitor identity; links a contact-form message or a reseller application to your earlier visits.
__hssc	30 minutes	HubSpot: counts page views in the current session.
__hssrc	Session	HubSpot: detects a new browser session.

Cookie	Duration	Description
_fbp	90 days	Meta (Meta Platforms Ireland Ltd. for the EEA): stores a unique ID to deliver and measure Facebook/Instagram ads, for the Meta pixels 1466808574144374 and 1230677305725443 (the second one through HubSpot ads).
_fbc	90 days	Meta: stores the ad click when you arrive from a Facebook or Instagram ad.
lastExternalReferrer, lastExternalReferrerTime, multiFbc (local storage)	Until cleared	Meta: the last other website that linked to ours and, after an ad click, its click IDs.
_gcl_au	90 days	Google Ads: links ad clicks to visits (conversion linker).
_gcl_aw, _gcl_dc, _gcl_gb	90 days	Google Ads conversion linker: stores the ad click (gclid, dclid, gbraid) when you arrive from a Google ad.
_gcl_ls (local storage)	90 days	Google Ads: conversion linker data in local storage.
li_fat_id	30 days	LinkedIn: stores the ad click when you arrive from a LinkedIn ad.
bcookie	1 year	LinkedIn: identifies the browser for the LinkedIn Insight tag.
li_gc	6 months	LinkedIn: stores your consent to non-essential LinkedIn cookies.
lidc	1 day	LinkedIn: selects the data center.
UserMatchHistory, AnalyticsSyncHistory, li_sugr, bscookie	30 days to 1 year	LinkedIn: set on linkedin.com by the Insight Tag, for example when you are signed in to LinkedIn; ad ID syncing and browser identification.
MUID, MR, SM, ANONCHK, SRM_B	Session to 13 months	Microsoft: set on clarity.ms and bing.com when Microsoft Clarity loads with this consent; identify the browser across Microsoft sites.
IDE	13 months in the EEA, Switzerland and the UK; 24 months elsewhere	Google: ad delivery and retargeting on doubleclick.net, when Google signals is active.