Attribute(bpy_struct)

Attributes are used to store data that corresponds to geometry elements. Geometry elements are items in one of the geometry domains like points, curves, or faces.

An attribute has a name, a type, and is stored on a domain.

name

The name of this attribute. Names have to be unique within the same geometry. If the name starts with a ., the attribute is hidden from the UI.

type

The type of data that this attribute stores, e.g. a float, integer, color, etc. See Attribute Type Items.

domain

The geometry domain that the attribute is stored on. See Attribute Domain Items.

Using Attributes

Attributes can be stored on geometries like Mesh, Curves, PointCloud, etc. These geometries have attribute groups (usually called attributes). Using the groups, attributes can then be accessed by their name:

radii = curves.attributes["radius"]

Creating and storing custom attributes is done using the attributes.new function:

# Add a new attribute named `my_attribute_name` of type `float` on the point domain of the geometry.
my_attribute = curves.attributes.new("my_attribute_name", 'FLOAT', 'POINT')

Removing attributes can be done like so:

attribute = drawing.attributes["some_attribute"]
drawing.attributes.remove(attribute)

Note

Some attributes are required and cannot be removed, like "position".

Attribute values are read by accessing their attribute.data collection property. However, in cases where multiple values should be read at once, it is better to use the bpy_prop_collection.foreach_get function and read the values into a numpy buffer.

import numpy as np

# Get the radius attribute.
radii = curves.attributes["radius"]
# Print the radius of the first point.
print(radii.data[0].value)
# Output: 0.005

# Get the total number of points.
num_points = attributes.domain_size('POINT')
# Create an empty buffer to read all the radii into.
radii_data = np.zeros(num_points, dtype=np.float32)
# Read all the radii of the curves into `radii_data` at once.
radii.data.foreach_get('value', radii_data)
# Print all the radii.
print(radii_data)
# Output: [0.1, 0.2, 0.3, 0.4, ... ]

Note

Some attribute types use different named properties to access their value. Instead of value, vectors use vector, and colors use color.

Writing to different attribute types is very similar. You can simply assign to a value directly. Again, when writing to multiple values, it is recommended to use the bpy_prop_collection.foreach_set function to write the values from a numpy buffer.

import numpy as np

radii = curves.attributes["radius"]
# Write a radius with a value of 0.5 to the first point.
radii.data[0].value = 0.5
print(radii.data[0].value)
# Output: 0.5

num_points = attributes.domain_size('POINT')
# Generate random radii with values between 0.001 and 0.05 using numpy.
new_radii = np.random.uniform(0.001, 0.05, num_points)
# Write the new radii to the radius attribute.
radii.data.foreach_set('value', new_radii)

The bpy_prop_collection.foreach_get / bpy_prop_collection.foreach_set methods require a flat array. This is sometimes not desirable, e.g. when reading/writing positions, which are 3D vectors. In these cases, it’s possible to use np.ravel to pass the data as a flat array:

num_points = attributes.domain_size('POINT')
positions = curves.attributes['position']
# Here, we're using a numpy array with shape (num_points, 3) so that each
# element is a 3d vector.
positions_data = np.zeros((num_points, 3), dtype=np.float32)
# The `np.ravel` function will pass the `positions_data` as a flat array
# without changing the original shape.
positions.data.foreach_get('vector', np.ravel(positions_data))
print(positions_data)
# Output: [[0.1, 0.2, 0.3], [0.4, 0.5, 0.6], ...]

base class — bpy_struct

subclasses — BoolAttribute, ByteColorAttribute, ByteIntAttribute, Float2Attribute, Float4x4Attribute, FloatAttribute, FloatColorAttribute, FloatVectorAttribute, Int2Attribute, IntAttribute, QuaternionAttribute, Short2Attribute, StringAttribute

class bpy.types.Attribute(bpy_struct)

Geometry attribute

data_type

Type of data stored in attribute

Type:

enum in Attribute Type Items, default ‘FLOAT’, (readonly)

domain

Domain of the Attribute

Type:

enum in Attribute Domain Items, default ‘POINT’, (readonly)

is_internal

The attribute is meant for internal use by Blender

Type:

boolean, default False, (readonly)

is_required

Whether the attribute can be removed or renamed

Type:

boolean, default False, (readonly)

name

Name of the Attribute

Type:

string, default “”, (never None)

classmethod bl_rna_get_subclass(id, default=None)
Parameters:

id (str) – The RNA type identifier.

Returns:

The RNA type or default when not found.

Return type:

bpy.types.Struct subclass

classmethod bl_rna_get_subclass_py(id, default=None)
Parameters:

id (str) – The RNA type identifier.

Returns:

The class or default when not found.

Return type:

type

Inherited Properties

Inherited Functions

References