blender python mesh edge

blender_python_mesh.md

How to get a list of edges of current face in bpy

[see blender.stackexcange] (http://blender.stackexchange.com/questions/6727/how-to-get-a-list-of-edges-of-current-face-in-bpy)

Standard API

The active face's index is accessible in the standard API (bpy) like:

me.polygons.active

To get the actual polygon, you do:

me.polygons[me.polygons.active]

Note that the index is 0 (first polygons) even if there's no face at all, and it's independent from vertex and edge selection (a face can be active without its edges or vertices being selected).

There's no direct access for a face's edges, you can create a dictionary from the edge_keys however:

import bpy

ob = bpy.context.object

if ob.type != 'MESH':
    raise TypeError("Active object is not a Mesh")

# Get editmode changes
ob.update_from_editmode()

me = ob.data

if len(me.polygons) < 1:
    raise ValueError("Mesh has no faces")

# Build lookup dictionary for edge keys to edges
edges = me.edges
face_edge_map = {ek: edges[i] for i, ek in enumerate(me.edge_keys)}

# Get active face by index
face = me.polygons[me.polygons.active]

selected = "selected"
not_selected = " ".join(("NOT", selected))

for ek in face.edge_keys:
    edge = face_edge_map[ek]
    print("%12s - %r" % ((selected if edge.select else not_selected), edge))

You can also do without such lookup dictionary, may use less memory and perform better, 'since there's just one face we need to find the edges of:

for ek in face.edge_keys:
    edge = me.edges[me.edge_keys.index(ek)]

Bmesh module

You can access the edges directly using the bmesh module (for edge in face.edges):

import bpy
import bmesh

ob = bpy.context.object

if ob.type != 'MESH':
    raise TypeError("Active object is not a Mesh")

me = ob.data

if me.is_editmode:
    # Gain direct access to the mesh
    bm = bmesh.from_edit_mesh(me)
else:
    # Create a bmesh from mesh
    # (won't affect mesh, unless explicitly written back)
    bm = bmesh.new()
    bm.from_mesh(me)


# Get active face
face = bm.faces.active

selected = "selected"
not_selected = " ".join(("NOT", selected))

for edge in face.edges:
    print("%12s - bm.edges[%i]" % ((selected if edge.select else not_selected), edge.index))


# No need to do anything here if you haven't changed the (b)mesh
# Otherwise, flush changes from wrapped bmesh / write back to mesh
"""
if me.is_editmode:
    bmesh.update_edit_mesh(me)
else:
    bm.to_mesh(me)
    me.update()

bm.free()
del bm
"""