How to use the command 'blender' (with examples)

The blender command is a command-line interface to the Blender 3D computer graphics application. It allows you to interact with Blender and perform tasks programmatically. This article provides examples of different use cases of the blender command.

Use case 1: Render all frames of an animation in the background

Code:

blender --background path/to/file.blend --render-anim

Motivation: This example is useful when you want to render all frames of an animation without loading the Blender user interface. It can be helpful for rendering large animations without the overhead of the UI.

Explanation:

• --background: Runs Blender in the background mode without loading the UI.
• path/to/file.blend: Specifies the path to the .blend file that contains the animation.
• --render-anim: Instructs Blender to render the animation.

Example output: The rendered frames of the animation are saved to the /tmp directory.

Use case 2: Render an animation using a specific image naming pattern

Code:

blender --background path/to/file.blend --render-output //render/frame_###.png --render-anim

Motivation: This example is useful when you want to render an animation using a specific image naming pattern. It allows you to define a custom output path and naming convention for the rendered frames.

Explanation:

• --render-output //render/frame_###.png: Sets the output path and image naming pattern for the rendered frames. The ### notation indicates a placeholder for the frame number.
• //: Specifies a path relative to the .blend file.

Example output: The rendered frames of the animation are saved as PNG images in the render directory relative to the .blend file.

Use case 3: Render a single frame of an animation

Code:

blender --background path/to/file.blend --render-output /path/to/output_directory --render-frame 10

Motivation: This example is useful when you only want to render a specific frame of an animation. It allows you to specify the frame number and the output directory.

Explanation:

• --render-frame 10: Specifies the frame number to render.
• /path/to/output_directory: Sets the output directory for the rendered frame.

Example output: The 10th frame of the animation is saved as an image in the specified output directory.

Use case 4: Render a specific frame of an animation as a JPEG image

Code:

blender --background path/to/file.blend --render-output //output_directory --render-frame JPEG --render-frame -2

Motivation: This example is useful when you want to render a specific frame of an animation in a different image format. It allows you to convert the frame to JPEG and choose a relative output directory.

Explanation:

• --render-frame JPEG: Specifies the image format to render the frame as.
• --render-frame -2: Renders the second last frame of the animation.

Example output: The second last frame of the animation is saved as a JPEG image in the specified output directory.

Use case 5: Render a specific scene of an animation within a frame range

Code:

blender --background path/to/file.blend --scene scene_name --frame-start 10 -e 500 --render-anim

Motivation: This example is useful when you want to render a specific scene within a defined frame range. It allows you to render a subset of the animation or focus on a particular scene.

Explanation:

• --scene scene_name: Specifies the scene to render.
• --frame-start 10 -e 500: Sets the start and end frame of the frame range to render.

Example output: The specified scene of the animation is rendered, starting from frame 10 and ending at frame 500.

Use case 6: Render an animation at a specific resolution using a Python expression

Code:

blender --background path/to/file.blend --python-expr 'import bpy; bpy.data.scenes[0].render.resolution_percentage = 25' --render-anim

Motivation: This example is useful when you want to render an animation at a specific resolution. It allows you to control the resolution through a Python expression.

Explanation:

• --python-expr 'import bpy; bpy.data.scenes[0].render.resolution_percentage = 25': Executes the provided Python expression, which sets the render resolution percentage to 25%.

Example output: The animation is rendered at the specified resolution percentage.

Use case 7: Start an interactive Blender session with a Python console

Code:

blender --background --python-console

Motivation: This example is useful when you want to start an interactive Blender session in the terminal. It allows you to perform live scripting and interact with Blender using a Python console.

Explanation:

• --python-console: Opens a Python console after starting the Blender session.

Example output: A Blender session starts in the terminal, and a Python console is available for interactive scripting.

Conclusion:

The blender command-line interface provides a wide range of capabilities for interacting with the Blender 3D computer graphics application. By using various arguments and options, you can render animations, control rendering parameters, and perform scripting tasks. The examples in this article demonstrate different use cases and highlight the versatility of the blender command.