Render from terminal

Overview

A Blender extension to write script file to launch renders from the terminal.

Write file .sh and, but poorly tested, .bat.

Launching renders from the command line is useful for:

• automating the rendering phase
• optimizing resources
• adding external commands (editing renders, uploading them online, sending messages...)
• launching the render remotely

With this addon the script creation is simplified and can then be modified and customized according to your needs.

With default values ​​this addon writes a script to start rendering the current frame with the project settings; clicking the "Write script" button creates a .sh and/or .bat file in the same folder as the .blend project, with the same name followed by "_render":[blend file name]_render.sh

This file is ready to be launched from the terminal with

./<nome blend file>_render.sh

---

The script

The created script has a function "startrender" which is called by passing several parameters:

• the name to give to the render empty string to use the project settings
• frames to render
  • 1,3: render frame 1 and 3
  • 1-3: render from frame 1 to frame 3, inclusive
  • 1..3: as 1-3
  • no value: the current frame when the "write script" button is pressed
• Resolution Scale as "Resolution scale" nel pannello "Format"
• render engine BLENDER_EEVEE_NEXT, BLENDER_WORKBENCH, CYCLES or empty string to use the project settings
• render quality "max samples" for Cycles and "samples" for Eevee
• scene to use
• whether or not it should overwrite the renders
• a python script to run before render

The values ​​for resolution percentage, render engine, render quality and overwrite are collected in a Python string that is passed to blender with the --python-expr parameter.
The other values ​​are passed with the corresponding blender command line parameters.

Use

Frame to render

In this panel you choose which frames to render

• Render only current frame: renders only the current frame; (the same result is obtained if you leave the "frames to render" field empty).

• Launch animation as in project launches the animation as set in the project; if the "Enable Override values" option is not selected in the script, Blender is launched with the -a option; if instead there are changes to the project settings ("Enable Override values" selected) Blender is launched passing the frame interval set with "Frame Start" and "End" of the animation.

• frames to render

  • 1,3: render frame 1 and 3
  • 1-3: render from frame 1 to frame 3 included
  • 1..3: as 1-3
  • the above values ​​can be entered together; e.g.; 1,3,5-10 (render frames 1 and 3, and frames 5 to 10)
  • no value: the current frame when the "write script" button is pressed

• animation as singles If there is an animation, e.g. 1-5, the command line does not have the animation -f 1..5, but the single separate frames: -f 1,2,3,4,5.
  Useful when used together with "new call each render"

• new call each render For each frame indicated in the "frames to render" field a blender call is made.
  For example:\

  • in the "frames to render" field there is: 1,3,5-8\
  • if "new call each render" NOT selected:\
    • Blender is launched only once by passing -f 1,3,5..8\
  • if "new call each render" is selected:\
    • Blender is launched three times, passing\
      • the first time -f 1\
      • the second time -f 3\
      • and the third time -f 5..8\
  • if "new call each render" is selected e also "animation as singles" is selected:\
    • Blender is launched six times, passing\
      • the first time -f 1\
      • the second time -f 3\
      • the third -f 5\
      • the fourth -f 6\
      • the fifth -f 7\
      • the sixth -f 8

This can be useful if you need to reload the entire project before each render.

Additional commands

These are commands that you want to run before or after the renders.

Warning: these values ​​will be copied into the script without any syntax checking or anything else.

• Start before launching the first Blender call
• Pre before launching any Blender call
• Python python file to pass to blender (-P pyfile.py)
• Post after each Blender call
• End after the last Blender call

Override values

With these values ​​the script will launch the renders by modifying the project settings.

• Enable Override values Enable override
• Output path Like the "Output path" field in the "Output" panel, if empty uses the project setting
• Override overwrite + Overwrite With "Override overwrite" selected it allows you to choose whether to overwrite the renders or not
• Override placeholder + Placeholder With "Override placeholder" selected it allows you to choose whether to create placeholder or not.

Note for multiple PCs or parallel sessions
If the script needs to be run on multiple computers or from different sessions (terminals) on the same computer, it is best to uncheck "overwrite" and check "placeholder" to avoid the same frame being rendered multiple times, even if these options are set differently in the project.

• Render Engine Choosing which render engine to use:\

  • Default (as set in the project)\
  • BLENDER_EEVEE_NEXT\
  • BLENDER_WORKBENCH\
  • CYCLES

• Samples rendering quality, "max samples" for Cycles and "samples" for Eevee

• % As "Resolution Scale", 0: Use project setting

• Scene Scene to load before launching the render (-S [scene name])

Multi instances render

By enabling this option, you can specify how many Blender instances will be launched in the script.
In practice, the script will contain a command that launches Blender as many times as specified in the "render session" field.

Warning
This option can be useful for speeding up rendering, for example when rendering from VSE or for projects with very fast EEVEE rendering, where multiple active Blender sessions can optimize the use of PC's resources.
Not all projects will benefit from using multiple, or parallel, instances.
However, this extension does not control any settings in project or extension that could lead to counterproductive results, so you should think carefully before using this option.
To render single frames, it is obviously pointless to launch multiple sessions.
If the "overwrite" option is selected in the project, or in the "overrides" of this extension, and the use of "placeholders" is not selected, the render sessions will all render the same frames, overwriting them. So it's best to always set the "overrides" by deselecting "overwrite" and selecting "placeholders."
If you select "animation as singles" along with "new call each render," the sessions will be launched to render one frame at a time, which is pointless.
So be careful with your settings and do some test.

Write script

Write the script:
[blend file name]_render.sh

Warning: The .bat file for Windows has not been adequately tested.