Blender is a popular 3D computer graphics application that allows users to create, model, animate, and render various objects and scenes. Alongside its graphical user interface (GUI), Blender also provides a command-line interface (CLI) that allows users to interact with the application using text-based commands. The CLI is known as “blender” and provides a range of functionality and options for performing tasks within Blender through scripting or automation.
Here are some key aspects and features of the Blender command-line interface:
- Command Execution: The Blender CLI allows users to execute commands in the order they are given. These commands can perform a variety of tasks, such as loading and manipulating 3D models, applying materials and textures, animating objects, rendering images or animations, and more. By executing commands from the command line, users can automate repetitive tasks or integrate Blender into scripts and pipelines.
- Scripting Capabilities: The Blender CLI supports scripting in Python, a powerful and popular programming language. Users can write Python scripts that interact with Blender’s functionality and execute them through the command line. This enables users to create complex workflows, automate tasks, and extend Blender’s capabilities beyond its built-in features.
- Command-Line Arguments: The Blender CLI accepts command-line arguments that modify its behavior and affect the execution of commands. These arguments can specify the input files to load, the output files to generate, rendering settings, animation parameters, scripting options, and more. By providing different arguments, users can customize their workflow and achieve specific results without manual intervention.
- Batch Processing: The Blender CLI is particularly useful for batch processing tasks. Users can provide a list of commands or scripts to execute in sequence, allowing them to process multiple files or perform repetitive operations automatically. This is beneficial for tasks such as rendering multiple frames of an animation, converting file formats, applying modifications to a set of models, and more.
- Integration with Automation Tools: The Blender CLI can be integrated into automation tools and workflows, enabling seamless integration with other software or systems. It can be used in conjunction with scripting languages, version control systems, build systems, or any tool that supports command-line execution. This integration allows for streamlined and efficient production pipelines for 3D content creation.
- Flexibility and Extensibility: The Blender CLI, combined with Python scripting, offers immense flexibility and extensibility. Users can leverage Blender’s extensive API to create custom tools, add-ons, or scripts that suit their specific needs. This flexibility allows users to adapt Blender to different workflows, industries, or specialized requirements.
- Documentation and Community Support: Blender has a thriving community of users and developers who actively contribute to its development and provide support. The Blender documentation and community resources offer extensive information and examples on using the Blender CLI, scripting, and automation. This support network ensures that users can access help, tutorials, and guidance to make the most of Blender’s command-line capabilities.
blender Command Examples
1. Render all frames of an animation in the background, without loading the UI (output is saved to /tmp):
# blender --background /path/to/file.blend --render-anim
2. Render an animation using a specific image naming pattern, in a path relative (//) to the .blend file:
# blender --background /path/to/file.blend --render-output //render/frame_###.png --render-anim
3. Render the 10th frame of an animation as a single image, saved to an existing directory (absolute path):
# blender --background /path/to/file.blend --render-output /path/to/output_directory --render-frame 10
4. Render the second last frame in an animation as a JPEG image, saved to an existing directory (relative path):
# blender --background /path/to/file.blend --render-output //output_directory --render-frame JPEG --render-frame -2
5. Render the animation of a specific scene, starting at frame 10 and ending at frame 500:
# blender --background /path/to/file.blend --scene scene_name --frame-start 10 -e 500 --render-anim
6. Render an animation at a specific resolution, by passing a Python expression:
# blender --background /path/to/file.blend --python-expr 'import bpy; bpy.data.scenes.render.resolution_percentage = 25' --render-anim
7. Start an interactive Blender session in the terminal with a python console (do import bpy after starting):
# blender --background --python-console
In summary, the Blender command-line interface (CLI) provides a powerful way to interact with Blender, the 3D computer graphics application. By executing commands from the command line, users can automate tasks, batch process files, create custom workflows, and integrate Blender into larger automation pipelines. Combined with Python scripting, the Blender CLI offers extensive flexibility and extensibility for 3D content creation and enables users to harness Blender’s capabilities to their fullest potential.