BMesh Types (bmesh.types)

Base Mesh Type

class bmesh.types.BMesh

The BMesh data structure

calc_loop_triangles()

Calculate triangle tessellation from quads/ngons.

Returns:The triangulated faces.
Return type:list of BMLoop tuples
calc_volume(signed=False)

Calculate mesh volume based on face normals.

Parameters:signed (bool) – when signed is true, negative values may be returned.
Returns:The volume of the mesh.
Return type:float
clear()

Clear all mesh data.

copy()
Returns:A copy of this BMesh.
Return type:BMesh
free()

Explicitly free the BMesh data from memory, causing exceptions on further access.

Note

The BMesh is freed automatically, typically when the script finishes executing. However in some cases its hard to predict when this will be and its useful to explicitly free the data.

from_mesh(mesh, face_normals=True, use_shape_key=False, shape_key_index=0)

Initialize this bmesh from existing mesh datablock.

Parameters:
  • mesh (Mesh) – The mesh data to load.
  • use_shape_key (boolean) – Use the locations from a shape key.
  • shape_key_index (int) – The shape key index to use.

Note

Multiple calls can be used to join multiple meshes.

Custom-data layers are only copied from mesh on initialization. Further calls will copy custom-data to matching layers, layers missing on the target mesh wont be added.

from_object(object, depsgraph, deform=True, cage=False, face_normals=True)

Initialize this bmesh from existing object datablock (currently only meshes are supported).

Parameters:
  • object (Object) – The object data to load.
  • deform (boolean) – Apply deformation modifiers.
  • cage (boolean) – Get the mesh as a deformed cage.
  • face_normals (boolean) – Calculate face normals.
normal_update()

Update mesh normals.

select_flush(select)

Flush selection, independent of the current selection mode.

Parameters:select (boolean) – flush selection or de-selected elements.
select_flush_mode()

flush selection based on the current mode current BMesh.select_mode.

to_mesh(mesh)

Writes this BMesh data into an existing Mesh datablock.

Parameters:mesh (Mesh) – The mesh data to write into.
transform(matrix, filter=None)

Transform the mesh (optionally filtering flagged data only).

Parameters:
  • matrix (4x4 mathutils.Matrix) – transform matrix.
  • filter (set) – set of values in (‘SELECT’, ‘HIDE’, ‘SEAM’, ‘SMOOTH’, ‘TAG’).
edges

This meshes edge sequence (read-only).

Type:BMEdgeSeq
faces

This meshes face sequence (read-only).

Type:BMFaceSeq
is_valid

True when this element is valid (hasn’t been removed).

Type:boolean
is_wrapped

True when this mesh is owned by blender (typically the editmode BMesh).

Type:boolean
loops

This meshes loops (read-only).

Type:BMLoopSeq

Note

Loops must be accessed via faces, this is only exposed for layer access.

select_history

Sequence of selected items (the last is displayed as active).

Type:BMEditSelSeq
select_mode

The selection mode, values can be {‘VERT’, ‘EDGE’, ‘FACE’}, can’t be assigned an empty set.

Type:set
verts

This meshes vert sequence (read-only).

Type:BMVertSeq

Mesh Elements

class bmesh.types.BMVert

The BMesh vertex type

calc_edge_angle(fallback=None)

Return the angle between this vert’s two connected edges.

Parameters:fallback (any) – return this when the vert doesn’t have 2 edges (instead of raising a ValueError).
Returns:Angle between edges in radians.
Return type:float
calc_shell_factor()

Return a multiplier calculated based on the sharpness of the vertex. Where a flat surface gives 1.0, and higher values sharper edges. This is used to maintain shell thickness when offsetting verts along their normals.

Returns:offset multiplier
Return type:float
copy_from(other)

Copy values from another element of matching type.

copy_from_face_interp(face)

Interpolate the customdata from a face onto this loop (the loops vert should overlap the face).

Parameters:face (BMFace) – The face to interpolate data from.
copy_from_vert_interp(vert_pair, fac)

Interpolate the customdata from a vert between 2 other verts.

Parameters:vert_pair (BMVert) – The vert to interpolate data from.
hide_set(hide)

Set the hide state. This is different from the hide attribute because it updates the selection and hide state of associated geometry.

Parameters:hide (boolean) – Hidden or visible.
normal_update()

Update vertex normal.

select_set(select)

Set the selection. This is different from the select attribute because it updates the selection state of associated geometry.

Parameters:select (boolean) – Select or de-select.

Note

Currently this only flushes down, so selecting a face will select all its vertices but de-selecting a vertex won’t de-select all the faces that use it, before finishing with a mesh typically flushing is still needed.

co

The coordinates for this vertex as a 3D, wrapped vector.

Type:mathutils.Vector
hide

Hidden state of this element.

Type:boolean
index

Index of this element.

Type:int

Note

This value is not necessarily valid, while editing the mesh it can become dirty.

It’s also possible to assign any number to this attribute for a scripts internal logic.

To ensure the value is up to date - see BMElemSeq.index_update.

is_boundary

True when this vertex is connected to boundary edges (read-only).

Type:boolean
is_manifold

True when this vertex is manifold (read-only).

Type:boolean
is_valid

True when this element is valid (hasn’t been removed).

Type:boolean
is_wire

True when this vertex is not connected to any faces (read-only).

Type:boolean

Edges connected to this vertex (read-only).

Type:BMElemSeq of BMEdge

Faces connected to this vertex (read-only).

Type:BMElemSeq of BMFace

Loops that use this vertex (read-only).

Type:BMElemSeq of BMLoop
normal

The normal for this vertex as a 3D, wrapped vector.

Type:mathutils.Vector
select

Selected state of this element.

Type:boolean
tag

Generic attribute scripts can use for own logic

Type:boolean
class bmesh.types.BMEdge

The BMesh edge connecting 2 verts

calc_face_angle(fallback=None)
Parameters:fallback (any) – return this when the edge doesn’t have 2 faces (instead of raising a ValueError).
Returns:The angle between 2 connected faces in radians.
Return type:float
calc_face_angle_signed(fallback=None)
Parameters:fallback (any) – return this when the edge doesn’t have 2 faces (instead of raising a ValueError).
Returns:The angle between 2 connected faces in radians (negative for concave join).
Return type:float
calc_length()
Returns:The length between both verts.
Return type:float
calc_tangent(loop)

Return the tangent at this edge relative to a face (pointing inward into the face). This uses the face normal for calculation.

Parameters:loop (BMLoop) – The loop used for tangent calculation.
Returns:a normalized vector.
Return type:mathutils.Vector
copy_from(other)

Copy values from another element of matching type.

hide_set(hide)

Set the hide state. This is different from the hide attribute because it updates the selection and hide state of associated geometry.

Parameters:hide (boolean) – Hidden or visible.
normal_update()

Update edges vertex normals.

other_vert(vert)

Return the other vertex on this edge or None if the vertex is not used by this edge.

Parameters:vert (BMVert) – a vert in this edge.
Returns:The edges other vert.
Return type:BMVert or None
select_set(select)

Set the selection. This is different from the select attribute because it updates the selection state of associated geometry.

Parameters:select (boolean) – Select or de-select.

Note

Currently this only flushes down, so selecting a face will select all its vertices but de-selecting a vertex won’t de-select all the faces that use it, before finishing with a mesh typically flushing is still needed.

hide

Hidden state of this element.

Type:boolean
index

Index of this element.

Type:int

Note

This value is not necessarily valid, while editing the mesh it can become dirty.

It’s also possible to assign any number to this attribute for a scripts internal logic.

To ensure the value is up to date - see BMElemSeq.index_update.

is_boundary

True when this edge is at the boundary of a face (read-only).

Type:boolean
is_contiguous

True when this edge is manifold, between two faces with the same winding (read-only).

Type:boolean
is_convex

True when this edge joins two convex faces, depends on a valid face normal (read-only).

Type:boolean
is_manifold

True when this edge is manifold (read-only).

Type:boolean
is_valid

True when this element is valid (hasn’t been removed).

Type:boolean
is_wire

True when this edge is not connected to any faces (read-only).

Type:boolean

Faces connected to this edge, (read-only).

Type:BMElemSeq of BMFace

Loops connected to this edge, (read-only).

Type:BMElemSeq of BMLoop
seam

Seam for UV unwrapping.

Type:boolean
select

Selected state of this element.

Type:boolean
smooth

Smooth state of this element.

Type:boolean
tag

Generic attribute scripts can use for own logic

Type:boolean
verts

Verts this edge uses (always 2), (read-only).

Type:BMElemSeq of BMVert
class bmesh.types.BMFace

The BMesh face with 3 or more sides

calc_area()

Return the area of the face.

Returns:Return the area of the face.
Return type:float
calc_center_bounds()

Return bounds center of the face.

Returns:a 3D vector.
Return type:mathutils.Vector
calc_center_median()

Return median center of the face.

Returns:a 3D vector.
Return type:mathutils.Vector
calc_center_median_weighted()

Return median center of the face weighted by edge lengths.

Returns:a 3D vector.
Return type:mathutils.Vector
calc_perimeter()

Return the perimeter of the face.

Returns:Return the perimeter of the face.
Return type:float
calc_tangent_edge()

Return face tangent based on longest edge.

Returns:a normalized vector.
Return type:mathutils.Vector
calc_tangent_edge_diagonal()

Return face tangent based on the edge farthest from any vertex.

Returns:a normalized vector.
Return type:mathutils.Vector
calc_tangent_edge_pair()

Return face tangent based on the two longest disconnected edges.

  • Tris: Use the edge pair with the most similar lengths.
  • Quads: Use the longest edge pair.
  • NGons: Use the two longest disconnected edges.
Returns:a normalized vector.
Return type:mathutils.Vector
calc_tangent_vert_diagonal()

Return face tangent based on the two most distent vertices.

Returns:a normalized vector.
Return type:mathutils.Vector
copy(verts=True, edges=True)

Make a copy of this face.

Parameters:
  • verts (boolean) – When set, the faces verts will be duplicated too.
  • edges (boolean) – When set, the faces edges will be duplicated too.
Returns:

The newly created face.
Return type:

BMFace
copy_from(other)

Copy values from another element of matching type.

copy_from_face_interp(face, vert=True)

Interpolate the customdata from another face onto this one (faces should overlap).

Parameters:
  • face (BMFace) – The face to interpolate data from.
  • vert (boolean) – When True, also copy vertex data.
hide_set(hide)

Set the hide state. This is different from the hide attribute because it updates the selection and hide state of associated geometry.

Parameters:hide (boolean) – Hidden or visible.
normal_flip()

Reverses winding of a face, which flips its normal.

normal_update()

Update face’s normal.

select_set(select)

Set the selection. This is different from the select attribute because it updates the selection state of associated geometry.

Parameters:select (boolean) – Select or de-select.

Note

Currently this only flushes down, so selecting a face will select all its vertices but de-selecting a vertex won’t de-select all the faces that use it, before finishing with a mesh typically flushing is still needed.

edges

Edges of this face, (read-only).

Type:BMElemSeq of BMEdge
hide

Hidden state of this element.

Type:boolean
index

Index of this element.

Type:int

Note

This value is not necessarily valid, while editing the mesh it can become dirty.

It’s also possible to assign any number to this attribute for a scripts internal logic.

To ensure the value is up to date - see BMElemSeq.index_update.

is_valid

True when this element is valid (hasn’t been removed).

Type:boolean
loops

Loops of this face, (read-only).

Type:BMElemSeq of BMLoop
material_index

The face’s material index.

Type:int
normal

The normal for this face as a 3D, wrapped vector.

Type:mathutils.Vector
select

Selected state of this element.

Type:boolean
smooth

Smooth state of this element.

Type:boolean
tag

Generic attribute scripts can use for own logic

Type:boolean
verts

Verts of this face, (read-only).

Type:BMElemSeq of BMVert
class bmesh.types.BMLoop

This is normally accessed from BMFace.loops where each face loop represents a corner of the face.

calc_angle()

Return the angle at this loops corner of the face. This is calculated so sharper corners give lower angles.

Returns:The angle in radians.
Return type:float
calc_normal()

Return normal at this loops corner of the face. Falls back to the face normal for straight lines.

Returns:a normalized vector.
Return type:mathutils.Vector
calc_tangent()

Return the tangent at this loops corner of the face (pointing inward into the face). Falls back to the face normal for straight lines.

Returns:a normalized vector.
Return type:mathutils.Vector
copy_from(other)

Copy values from another element of matching type.

copy_from_face_interp(face, vert=True, multires=True)

Interpolate the customdata from a face onto this loop (the loops vert should overlap the face).

Parameters:
  • face (BMFace) – The face to interpolate data from.
  • vert (boolean) – When enabled, interpolate the loops vertex data (optional).
  • multires (boolean) – When enabled, interpolate the loops multires data (optional).
edge

The loop’s edge (between this loop and the next), (read-only).

Type:BMEdge
face

The face this loop makes (read-only).

Type:BMFace
index

Index of this element.

Type:int

Note

This value is not necessarily valid, while editing the mesh it can become dirty.

It’s also possible to assign any number to this attribute for a scripts internal logic.

To ensure the value is up to date - see BMElemSeq.index_update.

is_convex

True when this loop is at the convex corner of a face, depends on a valid face normal (read-only).

Type:boolean
is_valid

True when this element is valid (hasn’t been removed).

Type:boolean

The next face corner (read-only).

Type:BMLoop

The previous face corner (read-only).

Type:BMLoop

The next loop around the edge (read-only).

Type:BMLoop

The previous loop around the edge (read-only).

Type:BMLoop

Loops connected to this loop, (read-only).

Type:BMElemSeq of BMLoop
tag

Generic attribute scripts can use for own logic

Type:boolean
vert

The loop’s vertex (read-only).

Type:BMVert

Sequence Accessors

class bmesh.types.BMElemSeq

General sequence type used for accessing any sequence of BMVert, BMEdge, BMFace, BMLoop.

When accessed via BMesh.verts, BMesh.edges, BMesh.faces there are also functions to create/remomove items.

index_update()

Initialize the index values of this sequence.

This is the equivalent of looping over all elements and assigning the index values.

for index, ele in enumerate(sequence):
    ele.index = index

Note

Running this on sequences besides BMesh.verts, BMesh.edges, BMesh.faces works but wont result in each element having a valid index, instead its order in the sequence will be set.

class bmesh.types.BMVertSeq
ensure_lookup_table()

Ensure internal data needed for int subscription is initialized with verts/edges/faces, eg bm.verts[index].

This needs to be called again after adding/removing data in this sequence.

index_update()

Initialize the index values of this sequence.

This is the equivalent of looping over all elements and assigning the index values.

for index, ele in enumerate(sequence):
    ele.index = index

Note

Running this on sequences besides BMesh.verts, BMesh.edges, BMesh.faces works but wont result in each element having a valid index, instead its order in the sequence will be set.

new(co=(0.0, 0.0, 0.0), example=None)

Create a new vertex.

Parameters:
  • co (float triplet) – The initial location of the vertex (optional argument).
  • example (BMVert) – Existing vert to initialize settings.
Returns:

The newly created edge.
Return type:

BMVert
remove(vert)

Remove a vert.

sort(key=None, reverse=False)

Sort the elements of this sequence, using an optional custom sort key. Indices of elements are not changed, BMElemeSeq.index_update() can be used for that.

Parameters:
  • key – The key that sets the ordering of the elements.
  • reverse – Reverse the order of the elements

Note

When the ‘key’ argument is not provided, the elements are reordered following their current index value. In particular this can be used by setting indices manually before calling this method.

Warning

Existing references to the N’th element, will continue to point the data at that index.

layers

custom-data layers (read-only).

Type:BMLayerAccessVert
class bmesh.types.BMEdgeSeq
ensure_lookup_table()

Ensure internal data needed for int subscription is initialized with verts/edges/faces, eg bm.verts[index].

This needs to be called again after adding/removing data in this sequence.

get(verts, fallback=None)

Return an edge which uses the verts passed.

Parameters:
  • verts (BMVert) – Sequence of verts.
  • fallback – Return this value if nothing is found.
Returns:

The edge found or None
Return type:

BMEdge
index_update()

Initialize the index values of this sequence.

This is the equivalent of looping over all elements and assigning the index values.

for index, ele in enumerate(sequence):
    ele.index = index

Note

Running this on sequences besides BMesh.verts, BMesh.edges, BMesh.faces works but wont result in each element having a valid index, instead its order in the sequence will be set.

new(verts, example=None)

Create a new edge from a given pair of verts.

Parameters:
  • verts (pair of BMVert) – Vertex pair.
  • example (BMEdge) – Existing edge to initialize settings (optional argument).
Returns:

The newly created edge.
Return type:

BMEdge
remove(edge)

Remove an edge.

sort(key=None, reverse=False)

Sort the elements of this sequence, using an optional custom sort key. Indices of elements are not changed, BMElemeSeq.index_update() can be used for that.

Parameters:
  • key – The key that sets the ordering of the elements.
  • reverse – Reverse the order of the elements

Note

When the ‘key’ argument is not provided, the elements are reordered following their current index value. In particular this can be used by setting indices manually before calling this method.

Warning

Existing references to the N’th element, will continue to point the data at that index.

layers

custom-data layers (read-only).

Type:BMLayerAccessEdge
class bmesh.types.BMFaceSeq
ensure_lookup_table()

Ensure internal data needed for int subscription is initialized with verts/edges/faces, eg bm.verts[index].

This needs to be called again after adding/removing data in this sequence.

get(verts, fallback=None)

Return a face which uses the verts passed.

Parameters:
  • verts (BMVert) – Sequence of verts.
  • fallback – Return this value if nothing is found.
Returns:

The face found or None
Return type:

BMFace
index_update()

Initialize the index values of this sequence.

This is the equivalent of looping over all elements and assigning the index values.

for index, ele in enumerate(sequence):
    ele.index = index

Note

Running this on sequences besides BMesh.verts, BMesh.edges, BMesh.faces works but wont result in each element having a valid index, instead its order in the sequence will be set.

new(verts, example=None)

Create a new face from a given set of verts.

Parameters:
  • verts (BMVert) – Sequence of 3 or more verts.
  • example (BMFace) – Existing face to initialize settings (optional argument).
Returns:

The newly created face.
Return type:

BMFace
remove(face)

Remove a face.

sort(key=None, reverse=False)

Sort the elements of this sequence, using an optional custom sort key. Indices of elements are not changed, BMElemeSeq.index_update() can be used for that.

Parameters:
  • key – The key that sets the ordering of the elements.
  • reverse – Reverse the order of the elements

Note

When the ‘key’ argument is not provided, the elements are reordered following their current index value. In particular this can be used by setting indices manually before calling this method.

Warning

Existing references to the N’th element, will continue to point the data at that index.

active

active face.

Type:BMFace or None
layers

custom-data layers (read-only).

Type:BMLayerAccessFace
class bmesh.types.BMLoopSeq
layers

custom-data layers (read-only).

Type:BMLayerAccessLoop
class bmesh.types.BMIter

Internal BMesh type for looping over verts/faces/edges, used for iterating over BMElemSeq types.

Selection History

class bmesh.types.BMEditSelSeq
add(element)

Add an element to the selection history (no action taken if its already added).

clear()

Empties the selection history.

discard(element)

Discard an element from the selection history.

Like remove but doesn’t raise an error when the elements not in the selection list.

remove(element)

Remove an element from the selection history.

validate()

Ensures all elements in the selection history are selected.

active

The last selected element or None (read-only).

Type:BMVert, BMEdge or BMFace
class bmesh.types.BMEditSelIter

Custom-Data Layer Access

class bmesh.types.BMLayerAccessVert

Exposes custom-data layer attributes.

bevel_weight

Bevel weight float in [0 - 1].

Type:BMLayerCollection
deform

Vertex deform weight BMDeformVert (TODO).

type: BMLayerCollection

float

Generic float custom-data layer.

type: BMLayerCollection

int

Generic int custom-data layer.

type: BMLayerCollection

paint_mask

Accessor for paint mask layer.

type: BMLayerCollection

shape

Vertex shapekey absolute location (as a 3D Vector).

Type:BMLayerCollection
skin

Accessor for skin layer.

type: BMLayerCollection

string

Generic string custom-data layer (exposed as bytes, 255 max length).

type: BMLayerCollection

class bmesh.types.BMLayerAccessEdge

Exposes custom-data layer attributes.

bevel_weight

Bevel weight float in [0 - 1].

Type:BMLayerCollection
crease

Edge crease for subsurf - float in [0 - 1].

Type:BMLayerCollection
float

Generic float custom-data layer.

type: BMLayerCollection

freestyle

Accessor for Freestyle edge layer.

type: BMLayerCollection

int

Generic int custom-data layer.

type: BMLayerCollection

string

Generic string custom-data layer (exposed as bytes, 255 max length).

type: BMLayerCollection

class bmesh.types.BMLayerAccessFace

Exposes custom-data layer attributes.

face_map

FaceMap custom-data layer.

type: BMLayerCollection

float

Generic float custom-data layer.

type: BMLayerCollection

freestyle

Accessor for Freestyle face layer.

type: BMLayerCollection

int

Generic int custom-data layer.

type: BMLayerCollection

string

Generic string custom-data layer (exposed as bytes, 255 max length).

type: BMLayerCollection

class bmesh.types.BMLayerAccessLoop

Exposes custom-data layer attributes.

color

Accessor for vertex color layer.

type: BMLayerCollection

float

Generic float custom-data layer.

type: BMLayerCollection

int

Generic int custom-data layer.

type: BMLayerCollection

string

Generic string custom-data layer (exposed as bytes, 255 max length).

type: BMLayerCollection

uv

Accessor for BMLoopUV UV (as a 2D Vector).

type: BMLayerCollection

class bmesh.types.BMLayerCollection

Gives access to a collection of custom-data layers of the same type and behaves like python dictionaries, except for the ability to do list like index access.

get(key, default=None)

Returns the value of the layer matching the key or default when not found (matches pythons dictionary function of the same name).

Parameters:
  • key (string) – The key associated with the layer.
  • default (Undefined) – Optional argument for the value to return if key is not found.
items()

Return the identifiers of collection members (matching pythons dict.items() functionality).

Returns:(key, value) pairs for each member of this collection.
Return type:list of tuples
keys()

Return the identifiers of collection members (matching pythons dict.keys() functionality).

Returns:the identifiers for each member of this collection.
Return type:list of strings
new(name)

Create a new layer

Parameters:name (string) – Optional name argument (will be made unique).
Returns:The newly created layer.
Return type:BMLayerItem
remove(layer)

Remove a layer

Parameters:layer (BMLayerItem) – The layer to remove.
values()

Return the values of collection (matching pythons dict.values() functionality).

Returns:the members of this collection.
Return type:list
verify()

Create a new layer or return an existing active layer

Returns:The newly verified layer.
Return type:BMLayerItem
active

The active layer of this type (read-only).

Type:BMLayerItem
is_singleton

True if there can exists only one layer of this type (read-only).

Type:boolean
class bmesh.types.BMLayerItem

Exposes a single custom data layer, their main purpose is for use as item accessors to custom-data when used with vert/edge/face/loop data.

copy_from(other)

Return a copy of the layer

Parameters:
  • other – Another layer to copy from.
  • other – BMLayerItem
name

The layers unique name (read-only).

Type:string

Custom-Data Layer Types

class bmesh.types.BMLoopUV
pin_uv

UV pin state.

Type:boolean
select

UV select state.

Type:boolean
select_edge

UV edge select state.

Type:boolean
uv

Loops UV (as a 2D Vector).

Type:mathutils.Vector
class bmesh.types.BMDeformVert
clear()

Clears all weights.

get(key, default=None)

Returns the deform weight matching the key or default when not found (matches pythons dictionary function of the same name).

Parameters:
  • key (int) – The key associated with deform weight.
  • default (Undefined) – Optional argument for the value to return if key is not found.
items()

Return (group, weight) pairs for this vertex (matching pythons dict.items() functionality).

Returns:(key, value) pairs for each deform weight of this vertex.
Return type:list of tuples
keys()

Return the group indices used by this vertex (matching pythons dict.keys() functionality).

Returns:the deform group this vertex uses
Return type:list of ints
values()

Return the weights of the deform vertex (matching pythons dict.values() functionality).

Returns:The weights that influence this vertex
Return type:list of floats