Select Random Faces in Maya with Python Script from ChatGPT

Select random faces in Maya with Python script with a percentage slider that can speed up your workflow. This Python script has been generated with chatGPT by a few prompts.

In a previus article we explored how to select random faces in Maya with a mel script. That script eventhough was great and did the job, it didn’t have a percentage slider UI, so we had to change the percentage through the Script Editor in Maya, each time we needed to.

What this Python script does:

It randomly selects faces in our geometry we specify with a percentage slider. Everytime we run the script it select different faces, based on the slider percentage we specify. We can run this tool per object, that means we select one 3d object and run it, not multiselected objects.

Random Faces Python Script Generated from chatGPT:

As I said, I generated this script with chatGPT.

My first prompt was the following (left-click to expand the scripts):

import maya.cmds as cmds
import random

def select_random_faces(percentage=10):
    """
    Selects random faces on the currently selected polygon object.

    Args:
        percentage (int): The percentage of total faces to select.
    """
    # Get the current selection
    selection = cmds.ls(selection=True, dag=True, shapes=True)

    if not selection:
        cmds.warning("No polygon object selected.")
        return

    # Get all faces of the selected object
    face_count = cmds.polyEvaluate(selection[0], face=True)

    # Calculate the number of faces to select
    num_faces_to_select = max(1, int(face_count * (percentage / 100.0)))

    # Generate a list of random face indices
    face_indices = list(range(face_count))
    random.shuffle(face_indices)
    random_faces = face_indices[:num_faces_to_select]

    # Construct face selection strings
    face_selection = [f"{selection[0]}.f[{i}]" for i in random_faces]

    # Select the random faces
    cmds.select(face_selection, replace=True)
    print(f"Selected {len(random_faces)} random faces on {selection[0]}.")

# Example usage: Adjust the percentage as needed
select_random_faces(percentage=15)

Eventhough it was working pretty well, i didn’t want to change the percentage value manually through the Script Editor in Maya. The same thing pretty much does the previous mel script, so the new one wasn’t really an upgraded.

In that case, i had to open up everytime the python script in the Script Editor in Maya, and go all over the end, to find the last code line and change the value 15, which is the percentage value to something else.

# Example usage: Adjust the percentage as needed
select_random_faces(percentage=15)

So my second prompt gave me what i wanted. The upgrade i need:

import maya.cmds as cmds
import random

def select_random_faces(percentage=10):
    """
    Selects random faces on the currently selected polygon object.

    Args:
        percentage (int): The percentage of total faces to select.
    """
    # Get the current selection
    selection = cmds.ls(selection=True, dag=True, shapes=True)

    if not selection:
        cmds.warning("No polygon object selected.")
        return

    # Get all faces of the selected object
    face_count = cmds.polyEvaluate(selection[0], face=True)

    # Calculate the number of faces to select
    num_faces_to_select = max(1, int(face_count * (percentage / 100.0)))

    # Generate a list of random face indices
    face_indices = list(range(face_count))
    random.shuffle(face_indices)
    random_faces = face_indices[:num_faces_to_select]

    # Construct face selection strings
    face_selection = [f"{selection[0]}.f[{i}]" for i in random_faces]

    # Select the random faces
    cmds.select(face_selection, replace=True)
    print(f"Selected {len(random_faces)} random faces on {selection[0]}.")

def create_ui():
    """
    Creates a UI with a slider to control the percentage of random faces to select.
    """
    window_name = "randomFacesUI"

    if cmds.window(window_name, exists=True):
        cmds.deleteUI(window_name)

    # Create the window
    window = cmds.window(window_name, title="Select Random Faces", widthHeight=(300, 100))
    cmds.columnLayout(adjustableColumn=True)

    # Add a slider for percentage
    slider = cmds.intSliderGrp(
        field=True,
        label="Percentage:",
        minValue=1,
        maxValue=100,
        value=10
    )

    # Add a button to execute the selection
    cmds.button(
        label="Select Random Faces",
        command=lambda x: select_random_faces(cmds.intSliderGrp(slider, query=True, value=True))
    )

    # Show the window
    cmds.showWindow(window)

# Create the UI
create_ui()

As a result chatGPT created the same python script, only this time, added a percentage slider on a UI, which is extremely helpful.

Random Faces with Slider in Maya:

In this demonstration I have created a terrain 3d object in Maya from a simple plane, by just pulling faces with soft selection technique, nothing special.

Select your 3d geometry and go and open the Sctipt Editor by going to Windows – General Editors – Script Editor.

Copy the second generated script from above, and paste it into the Script Editor in Maya.

Highligh the whole python script with ctrl+A, and press ctrl+enter to execute the script.

Our new Python UI window appears. Set the percentage slider as you please and hit select random faces on the same window.

After that do what you want with that random selected faces. In my case, i just pull them up, in order to create some noise as you can see in the image below:

Don’t forget to put the script into a shelf in Maya for easy access, in case you use it a lot into your projects.