Mesh(ID)

Mesh Data

The mesh data is accessed in object mode and intended for compact storage, for more flexible mesh editing from Python see bmesh.

Blender stores 4 main arrays to define mesh geometry.

• Mesh.vertices (3 points in space)

• Mesh.edges (reference 2 vertices)

• Mesh.loops (reference a single vertex and edge)

• Mesh.polygons: (reference a range of loops)

Each polygon references a slice in the loop array, this way, polygons do not store vertices or corner data such as UVs directly, only a reference to loops that the polygon uses.

Mesh.loops, Mesh.uv_layers Mesh.vertex_colors are all aligned so the same polygon loop indices can be used to find the UVs and vertex colors as with as the vertices.

To compare mesh API options see: NGons and Tessellation Faces

This example script prints the vertices and UVs for each polygon, assumes the active object is a mesh with UVs.

import bpy

me = bpy.context.object.data
uv_layer = me.uv_layers.active.data

for poly in me.polygons:
    print("Polygon index: {:d}, length: {:d}".format(poly.index, poly.loop_total))

    # Range is used here to show how the polygons reference loops,
    # for convenience 'poly.loop_indices' can be used instead.
    for loop_index in range(poly.loop_start, poly.loop_start + poly.loop_total):
        print("    Vertex: {:d}".format(me.loops[loop_index].vertex_index))
        print("    UV: {!r}".format(uv_layer[loop_index].uv))

base classes — bpy_struct, ID

class bpy.types.Mesh(ID)

Mesh data-block defining geometric surfaces

animation_data

Animation data for this data-block (readonly)

Type:

AnimData

attributes

Geometry attributes (default None, readonly)

Type:

AttributeGroupMesh[Attribute]

auto_texspace

Adjust active object’s texture space automatically when transforming object (default True)

Type:

bool

color_attributes

Geometry color attributes (default None, readonly)

Type:

AttributeGroupMesh[Attribute]

corner_normals

The “slit” normal direction of each face corner, influenced by vertex normals, sharp faces, sharp edges, and custom normals. May be empty. (default None, readonly)

Type:

bpy_prop_collection[MeshNormalValue]

cycles

Cycles mesh settings (readonly)

Type:

CyclesMeshSettings

edges

Edges of the mesh (default None, readonly)

Type:

MeshEdges[MeshEdge]

has_custom_normals

True if there is custom normal data for this mesh (default False, readonly)

Type:

bool

is_editmode

True when used in editmode (default False, readonly)

Type:

bool

loop_triangle_polygons

The face index for each loop triangle (default None, readonly)

Type:

bpy_prop_collection[ReadOnlyInteger]

loop_triangles

Tessellation of mesh polygons into triangles (default None, readonly)

Type:

MeshLoopTriangles[MeshLoopTriangle]

loops

Loops of the mesh (face corners) (default None, readonly)

Type:

MeshLoops[MeshLoop]

materials

(default None, readonly)

Type:

IDMaterials[Material]

normals_domain

The attribute domain that gives enough information to represent the mesh’s normals (default 'FACE', readonly)

Type:

Literal[‘POINT’, ‘FACE’, ‘CORNER’]

polygon_normals

The normal direction of each face, defined by the winding order and position of its vertices (default None, readonly)

Type:

bpy_prop_collection[MeshNormalValue]

polygons

Polygons of the mesh (default None, readonly)

Type:

MeshPolygons[MeshPolygon]

radial_symmetry

Number of mirrored regions around a central axis (array of 3 items, in [1, 64], default (1, 1, 1))

Type:

bpy_prop_array[int]

remesh_mode

(default 'VOXEL')

• VOXEL Voxel – Use the voxel remesher.

• QUAD Quad – Use the quad remesher.

Type:

Literal[‘VOXEL’, ‘QUAD’]

remesh_voxel_adaptivity

Reduces the final face count by simplifying geometry where detail is not needed, generating triangles. A value greater than 0 disables Fix Poles. (in [0, 1], default 0.0)

Type:

float

remesh_voxel_size

Size of the voxel in object space used for volume evaluation. Lower values preserve finer details. (in [0, inf], default 0.1)

Type:

float

shape_keys

(readonly)

Type:

Key

skin_vertices

All skin vertices (default None, readonly)

Type:

bpy_prop_collection[MeshSkinVertexLayer]

texco_mesh

Derive texture coordinates from another mesh

Type:

Mesh

texspace_location

Texture space location (array of 3 items, in [-inf, inf], default (0.0, 0.0, 0.0))

Type:

mathutils.Vector

texspace_size

Texture space size (array of 3 items, in [-inf, inf], default (1.0, 1.0, 1.0))

Type:

mathutils.Vector

texture_mesh

Use another mesh for texture indices (vertex indices must be aligned)

Type:

Mesh

total_edge_sel

Selected edge count in editmode (in [0, inf], default 0, readonly)

Type:

int

total_face_sel

Selected face count in editmode (in [0, inf], default 0, readonly)

Type:

int

total_vert_sel

Selected vertex count in editmode (in [0, inf], default 0, readonly)

Type:

int

use_auto_texspace

Adjust active object’s texture space automatically when transforming object (default True)

Type:

bool

use_mirror_topology

Use topology based mirroring (for when both sides of mesh have matching, unique topology) (default False)

Type:

bool

use_mirror_vertex_groups

Mirror the left/right vertex groups when painting. The symmetry axis is determined by the symmetry settings. (default True)

Type:

bool

use_mirror_x

Enable symmetry in the X axis (default False)

Type:

bool

use_mirror_y

Enable symmetry in the Y axis (default False)

Type:

bool

use_mirror_z

Enable symmetry in the Z axis (default False)

Type:

bool

use_paint_bone_selection

Bone selection during painting (default True)

Type:

bool

use_paint_mask

Face selection masking for painting (default False)

Type:

bool

use_paint_mask_vertex

Vertex selection masking for painting (default False)

Type:

bool

use_remesh_fix_poles

Produces fewer poles and a better topology flow (default False)

Type:

bool

use_remesh_preserve_attributes

Transfer all attributes to the new mesh (default False)

Type:

bool

use_remesh_preserve_volume

Projects the mesh to preserve the volume and details of the original mesh (default False)

Type:

bool

uv_layer_clone

UV loop layer to be used as cloning source

Type:

MeshUVLoopLayer

uv_layer_clone_index

Clone UV loop layer index (in [0, inf], default 0)

Type:

int

uv_layer_stencil

UV loop layer to mask the painted area

Type:

MeshUVLoopLayer

uv_layer_stencil_index

Mask UV loop layer index (in [0, inf], default 0)

Type:

int

uv_layers

All UV loop layers (default None, readonly)

Type:

UVLoopLayers[MeshUVLoopLayer]

vertex_colors

Legacy vertex color layers. Deprecated, use color attributes instead. (default None, readonly)

Type:

LoopColors[MeshLoopColorLayer]

vertex_normals

The normal direction of each vertex, defined as the average of the surrounding face normals (default None, readonly)

Type:

bpy_prop_collection[MeshNormalValue]

vertices

Vertices of the mesh (default None, readonly)

Type:

MeshVertices[MeshVertex]

edge_creases

Edge crease values for subdivision surface, corresponding to the “crease_edge” attribute.

(readonly)

edge_keys

(readonly)

vertex_creases

Vertex crease values for subdivision surface, corresponding to the “crease_vert” attribute.

(readonly)

vertex_paint_mask

Mask values for sculpting and painting, corresponding to the “.sculpt_mask” attribute.

(readonly)

transform(matrix, *, shape_keys=False)

Transform mesh vertices by a matrix (Warning: inverts normals if matrix is negative)

Parameters:

• matrix (mathutils.Matrix) – Matrix (multi-dimensional array of 4 * 4 items, in [-inf, inf])

• shape_keys (bool) – Transform Shape Keys (optional)

flip_normals()

Invert winding of all polygons (clears tessellation, does not handle custom normals)

set_sharp_from_angle(*, angle=3.14159)

Reset and fill the “sharp_edge” attribute based on the angle of faces neighboring manifold edges

Parameters:

angle (float) – Angle, Angle between faces beyond which edges are marked sharp (in [0, 3.14159], optional)

split_faces()

Split faces based on the edge angle

calc_tangents(*, uvmap='')

Compute tangents and bitangent signs, to be used together with the custom normals to get a complete tangent space for normal mapping (custom normals are also computed if not yet present)

Parameters:

uvmap (str) – Name of the UV map to use for tangent space computation (optional, never None)

free_tangents()

Free tangents

calc_loop_triangles()

Calculate loop triangle tessellation (supports editmode too)

calc_smooth_groups(*, use_bitflags=False, use_boundary_vertices_for_bitflags=False)

Calculate smooth groups from sharp edges

Parameters:

• use_bitflags (bool) – Produce bitflags groups instead of simple numeric values (optional)

• use_boundary_vertices_for_bitflags (bool) – Also consider different smoothgroups sharing only vertices (but without any common edge) as neighbors, preventing them from sharing the same bitflag value. Only effective when use_bitflags is set. WARNING: Will overflow (run out of available bits) easily with some types of topology, e.g. large fans of sharp edges (optional)

Returns:

poly_groups, Smooth Groups, bpy_prop_array[int]

groups, Total number of groups, int

Return type:

tuple[bpy_prop_array[int], int]

normals_split_custom_set(normals)

Define custom normals of this mesh (use zero-vectors to keep auto ones)

Parameters:

normals (Sequence[float]) – Normals (multi-dimensional array of 1 * 3 items, in [-1, 1])

normals_split_custom_set_from_vertices(normals)

Define custom normals of this mesh, from vertices’ normals (use zero-vectors to keep auto ones)

Parameters:

normals (Sequence[float]) – Normals (multi-dimensional array of 1 * 3 items, in [-1, 1])

update(*, calc_edges=False, calc_edges_loose=False)

update

Parameters:

• calc_edges (bool) – Calculate Edges, Force recalculation of edges (optional)

• calc_edges_loose (bool) – Calculate Loose Edges, Calculate the loose state of each edge (optional)

update_gpu_tag()

update_gpu_tag

unit_test_compare(*, mesh=None, threshold=7.1526e-06)

unit_test_compare

Parameters:

• mesh (Mesh) – Mesh to compare to (optional)

• threshold (float) – Threshold, Comparison tolerance threshold (in [0, inf], optional)

Returns:

Return value, String description of result of comparison (never None)

Return type:

str

clear_geometry()

Remove all geometry from the mesh. Note that this does not free shape keys or materials.

validate(*, verbose=False, clean_customdata=True)

Validate geometry, return True when the mesh has had invalid geometry corrected/removed

Parameters:

• verbose (bool) – Verbose, Output information about the errors found (optional)

• clean_customdata (bool) – Clean Custom Data, Deprecated, has no effect (optional)

Returns:

Result

Return type:

bool

validate_material_indices()

Validate material indices of polygons, return True when the mesh has had invalid indices corrected (to default 0)

Returns:

Result

Return type:

bool

count_selected_items()

Return the number of selected items (vert, edge, face)

Returns:

Result, (array of 3 items, in [0, inf])

Return type:

bpy_prop_array[int]

edge_creases_ensure()

edge_creases_remove()

from_pydata(vertices, edges, faces, shade_flat=True)

Make a mesh from a list of vertices/edges/faces Until we have a nicer way to make geometry, use this.

Parameters:

• vertices (Iterable[Sequence[float]]) – float triplets each representing (X, Y, Z) eg: [(0.0, 1.0, 0.5), …].

• edges (Iterable[Sequence[int]]) –

  int pairs, each pair contains two indices to the vertices argument. eg: [(1, 2), …]

  When an empty iterable is passed in, the edges are inferred from the polygons.

• faces (Iterable[Sequence[int]]) – iterator of faces, each faces contains three or more indices to the vertices argument. eg: [(5, 6, 8, 9), (1, 2, 3), …]

Warning

Invalid mesh data (out of range indices, edges with matching indices, 2 sided faces… etc) are not prevented. If the data used for mesh creation isn’t known to be valid, run Mesh.validate after this function.

shade_flat()

Render and display faces uniform, using face normals, setting the “sharp_face” attribute true for every face

shade_smooth()

Render and display faces smooth, using interpolated vertex normals, removing the “sharp_face” attribute

vertex_creases_ensure()

vertex_creases_remove()

vertex_paint_mask_ensure()

vertex_paint_mask_remove()

classmethod bl_rna_get_subclass(id, default=None, /)

Parameters:

• id (str) – The RNA type identifier.

• default (bpy.types.Struct | None) – The value to return when not found.

Returns:

The RNA type or default when not found.

Return type:

bpy.types.Struct

classmethod bl_rna_get_subclass_py(id, default=None, /)

Parameters:

• id (str) – The RNA type identifier.

• default (type | None) – The value to return when not found.

Returns:

The class or default when not found.

Return type:

type

Inherited Properties

bpy_struct.id_data ID.name ID.name_full ID.id_type ID.session_uid ID.is_evaluated ID.original ID.users ID.use_fake_user ID.use_extra_user ID.is_embedded_data

ID.is_linked_packed ID.is_missing ID.is_runtime_data ID.is_editable ID.tag ID.is_library_indirect ID.library ID.library_weak_reference ID.asset_data ID.override_library ID.preview

Inherited Functions

bpy_struct.as_pointer bpy_struct.driver_add bpy_struct.driver_remove bpy_struct.get bpy_struct.id_properties_clear bpy_struct.id_properties_ensure bpy_struct.id_properties_ui bpy_struct.is_property_hidden bpy_struct.is_property_overridable_library bpy_struct.is_property_readonly bpy_struct.is_property_set bpy_struct.items bpy_struct.keyframe_delete bpy_struct.keyframe_insert bpy_struct.keys bpy_struct.path_from_id bpy_struct.path_from_module bpy_struct.path_resolve bpy_struct.pop bpy_struct.property_overridable_library_set bpy_struct.property_unset bpy_struct.rna_ancestors

bpy_struct.type_recast bpy_struct.values ID.bl_system_properties_get ID.rename ID.evaluated_get ID.copy ID.asset_mark ID.asset_clear ID.asset_generate_preview ID.override_create ID.override_hierarchy_create ID.user_clear ID.user_remap ID.make_local ID.user_of_id ID.animation_data_create ID.animation_data_clear ID.update_tag ID.preview_ensure ID.bl_rna_get_subclass ID.bl_rna_get_subclass_py

References

bpy.context.mesh BlendData.meshes BlendDataMeshes.new BlendDataMeshes.new_from_object BlendDataMeshes.remove

Mesh.texco_mesh Mesh.texture_mesh Mesh.unit_test_compare Object.to_mesh