Python
30 May 2019

Maya Scripting Basics

Table of Contents

1. Create, Query, and Edit Flags in Maya

2. Get System Path of Maya

3. Writing and Running an External Script

4. Calling MEL Script with Python





1. Create, Query, and Edit Flags in Maya


  • "Create" flag is only relevant when first running the command, such as when you initially create a polygonal primitive eg: Create a Cube Command 
    myCube = cmds.polyCube()
  • "Query" flag can be queried after the command has been run and can be used to retrieve information about something in the scene eg: Use the query mode to store the new number of divisions to a variable 
    numOfDivisions = cmds.polyCube(myCube, query=True, subdivisionsX=True)
print(numOfDivisions)
# You should see "5.0" as the output.
  • "Edit" flag can be edited after the fact eg: Change the X subdivisions from the cube we created 
    cmds.polyCube(myCube, edit=True, subdivisionsX = 5)
  • "Multiple" flag can be used more than once in a single instance of the command (for example, to create specify multiple points when creating a curve)





2. Get System Path of Maya(Can store scripts)


import sys
pathList = sys.path
for path in pathList:
	print(path)

if we want to store scripts in our own directory

  1. create a python script

  2. import sys
sys.path.append('directory path')

  3. Let maya execute script everytime when runing the program, what we need to do is to save this file in

    Mac:

    ~/Library/Preference/Autodesk/maya/<version>/scripts

    Windows:

    <drive>:\Documents and Settings\<username>\My Documents\maya<version>\scripts





3. Writing and Running an External Script


When we want to runing an external script in maya, First thing is to make sure the script is in maya script folder, on Windows， it can be found in <drive>:\Documents and Settings\<username>\My Documents\maya<version>\scripts, on Mac can be found in ~/Library/Preference/Autodesk/maya/<version>/scripts

when import the script make sure to use reload() function to clear the caches.

For example:

if we have a python file with following code:

import maya.cmds as cmds
print("Imported the script!")
def makeObject():
    cmds.polyCube()
    print("Made a cube!")

We can call the function by running the following in maya

import myScript
reload(myScript)
myScript.makeObject()





4. Calling MEL Script with Python


Maya offers two different languages with which to create custom functionality via scripting—both Maya Embedded Language (MEL) scripts and Python. Normally we only want to use one of them, but some times we can call the mel script through python.


Code Example:

1.Create a Mel File add following:

global proc myMELScript()
{
    polyCube;
    print("Hello from MEL!");
}

2.Create a Python File add following:

import maya.cmds as cmds
import maya.mel as mel

def runMEL():
    print("Running MEL from Python")
    mel.eval("source myMELScript;")
    mel.eval("myMELScript;")

runMEL()

3.Run it in maya with

import runMEL
reload(runMEL)

End –Cheng Gu

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