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Tractor Dispatcher for Blender
Dispatch jobs to Pixar's Tractor render farm manager
UI location Properties → Render → Tractor Dispatcher
Usage See below
Version 1.0.0 Author(s) Ragnar Brynjulfsson
Blender 2.65 License GPL
Category Render Distribution Extern

Executable information
File name
Current version download
Python modules os, subprocess, time, tempfile, shutil
External Python Modules or dependencies Render farm running Pixar's Tractor Engine and in path

Warning Breaks Cycles texture paths in Blender 2.64 and earlier
Known Issues Tractor's progress bar runs once for each pass when doing motion blur in internal render

Tractor Dispatcher for Blender is a simple tool for dispatching jobs to a render farm managed by Pixar’s Tractor render manager. It can be used both for rendering, and for running arbitrary batch jobs defined by a Python scripts.

To use it you need a render farm running tractor-engine, Pixar Tractor licenses and in path when you start blender.


If running Blender 2.64 and Cycles, this tool will break the paths to your textures, due to a bug in Blender that has since been fixed. Either use Blender 2.65, or make sure you save your file BEFORE dispatching a render job, and reload it after you dispatch it. Note that the file saved in the spool folder will still be intact, so you can grab that if the script corrupts your file.


  1. Download the latest version of Tractor Dispatcher for Blender from the link above.
  2. Unpack the render_tractor_dispatcher.tar.gz, and copy into (blender_folder)/2.65/scripts/addons/
  3. In Blender open File>User Preferences…>Addons and enter tractor in the search field. And activate the Render:Tractor Dispatcher addon by checking the checkbox next to it.

You should now have a Tractor Dispatcher pane at the bottom of the Properties>Render panel that looks something like this.

UI Tractor Dispatcher for Blender.png

How to Use

Simply define a spool path (see below), assign a crew, and hit the Dispatch Job button. Tractor Dispatcher will create an .alf job script, save a copy of your .blend file and pre/post-scripts if you have any, and run


Render Scene

Tells Tractor that it should render the scene. You would un-check this if you only wanted to run a python script on the scene, and not render this. This way you can for instance use the Tractor Dispatcher to dispatch fluid simulations to your farm (though it will unfortunately only run on one render node).

Show Progress

This shows progress bars in Tractor for each frame. This uses some basic *nix tools, so if running this on Windows you want to un-check this box (note that this script has only been tested on Linux). If you’re using Blender’s internal renderer the progress bar will run from 0 to full for each motion blur pass, like the progress bar does in Blenders interface.

Priority, Crews and Envkey

These are all standard features of Tractor. See Pixar’s Tractor documentation for details.


Pre-Script is a python script file that is run before a single frame is rendered, and Post-Script is a python script file that is run after a all frames have finished rendering. If you want to run a script before or after rendering each frame, look into in the Blender documentation.

Spool Path

This is the path where the .alf job script that Tractor uses to know which frames to render is placed. It is also where a copy of your .blend file and your pre/post-scripts is saved, and where Tractor reads them from. This means that all your render nodes must have access to this path, as well as any other textures and files your .blend file needs to render.

Use Full Binary Path

This defines if the full path to Blender should be written in the .alf job script. This can be handy if you’re using multiple versions of Blender, and want to be able to render from different ones, otherwise you can leave it unchecked.

Release Notes

1.0.0 – First public release