use external python script to open maya and run another script inside maya

Question

Is it possible to call a script from the command prompt in windows (or bash in linux) to open Maya and then subsequently run a custom script (possibly changing each time its run) inside Maya? I am searching for something a bit more elegant than changing the userSetup file and then running Maya.

The goal here is to be able to open a .mb file, run a script to position the scene inside, setup a generic set of lights and then render the scene to a specific place and file type. I want to be able to set this up as a scheduled task to check for any new scene files in a directory and then open maya and go.

Thanks for the help!

Answer 1

For something like this you can use Maya standalone instead of the full blown UI mode. It is faster. It is ideal for batch scheduled jobs like these. Maya standalone is just Maya running without the GUI. Once you have initialized your Maya standalone, you can import and call any scripts you want, as part of the original calling script. To start you off here is an example: (Feel free to use this as a reference/modify it to meet your needs)

In your script you first initialize Maya standalone.

import maya.standalone
maya.standalone.initialize("Python")

import maya.cmds as cmds
cmds.loadPlugin("Mayatomr") # Load all plugins you might need

That will get Maya running. Now we open and/or import all the files necessary (egs. lights, models etc.)

# full path to your Maya file to OPEN
maya_file_to_open = r"C:/Where/Ever/Your/Maya_Scene_Files/Are/your_main_maya_file.mb"

# Open your file
opened_file = cmds.file(maya_file_to_open, o=True)

# full path to your Maya file to IMPORT
maya_file_to_import = r"C:/Where/Ever/Your/Maya_Scene_Files/Are/your_maya_file.mb"

# Have a namespace if you want (recommended)
namespace = "SomeNamespaceThatIsNotAnnoying" 

# Import the file. the variable "nodes" will hold the names of all nodes imported, just in case.
nodes = cmds.file(maya_file_to_import, i=True,
                          renameAll=True,
                          mergeNamespacesOnClash=False,
                          namespace=namespace,
                          returnNewNodes=True,
                          options="v=0;",
                          type="mayaBinary" # any file type you want. this is just an example.
                          )

#TODO: Do all your scene setup/ positioning etc. if needed here...
#Tip: you can use cmds.viewFit(cam_name, fitFactor=1) to fit your camera on to selected objects

Now we save this file out and call Maya Batch renderer to render it out

render_file = "C:/Where/Ever/Your/Maya_Scene_Files/Are/your_RENDER_file.mb"
cmds.file(rename=render_file)
cmds.file(force=True, save=True, options='v=1;p=17', type='mayaBinary')

import sys
from os import path
from subprocess import Popen

render_project = r"C:/Where/Ever/YourRenderProjectFolder"
renderer_folder = path.split(sys.executable)[0]
renderer_exec_name = "Render"
params = [renderer_exec_name]
params += ['-percentRes', '75']
params += ['-alpha', '0']
params += ['-proj', render_project]
params += ['-r', 'mr']
params += [render_file]
p = Popen(params, cwd=renderer_folder)
stdout, stderr = p.communicate()

That's it! Of Course, your script will have to be run using Maya's Python interpreter (Mayapy).

Do check out the docs for all the commands used for more options, esp.: cmds.file() cmds.viewFit() cmds.loadPlugin() Subprocess and Popen

PLUS, because of the awesomeness of Python, you can use modules like sched (docs) to schedule the running of this method in your Python code.

Hope this was useful. Have fun with this. Cheers.