blender-mesh-modeling

Create mesh from Python data

import bpy, bmesh

# 1. Create mesh datablock
mesh = bpy.data.meshes.new("PartMesh")

# 2. Fill with vertex/edge/face data
verts = [(-1,-1,0), (1,-1,0), (1,1,0), (-1,1,0),
         (-1,-1,2), (1,-1,2), (1,1,2), (-1,1,2)]
faces = [(0,1,2,3), (4,5,6,7), (0,1,5,4), (1,2,6,5), (2,3,7,6), (3,0,4,7)]
mesh.from_pydata(verts, [], faces)   # edges=[] lets Blender derive them from faces
mesh.update()

# 3. Wrap in object and link to scene
obj = bpy.data.objects.new("PartObj", mesh)
bpy.context.scene.collection.objects.link(obj)

from_pydata params:

• vertices — required, sequence of (x, y, z) tuples
• edges — list of (i, j) index pairs; pass [] when faces fully define connectivity
• faces — list of index sequences (tris, quads, or ngons)

BMesh workflow

bm = bmesh.new()
bm.from_mesh(mesh)      # load from existing mesh datablock

# ... topology edits (see ops below) ...

bm.to_mesh(mesh)        # write back
mesh.update()
bm.free()               # release memory

Always call bm.free() when done. Mode switches invalidate references — avoid in headless scripts.

BMesh operations

Extrude faces

top_faces = [f for f in bm.faces if f.calc_center_median().z > threshold]
ret = bmesh.ops.extrude_face_region(bm, geom=top_faces)
extruded_verts = [g for g in ret["geom"] if isinstance(g, bmesh.types.BMVert)]
bmesh.ops.translate(bm, verts=extruded_verts, vec=(0.0, 0.0, 1.0))

Op	Required params	Notes
bmesh.ops.extrude_face_region	bm, geom (faces/edges/verts)	Returns {"geom": [new elements]}
bmesh.ops.translate	bm, verts, vec=(x,y,z)	Object-local coordinates
bmesh.ops.triangulate	bm, faces	quad_method, ngon_method optional
bmesh.ops.remove_doubles	bm, verts, dist	See blender-mesh-repair
bmesh.ops.holes_fill	bm, edges, sides=0	See blender-mesh-repair

Triangulate all faces

bmesh.ops.triangulate(bm, faces=bm.faces[:])
# Optional: quad_method='BEAUTY', ngon_method='EAR_CLIP'

Filter geometry by position

top_faces   = [f for f in bm.faces if f.calc_center_median().z > 1.0]
outer_verts = [v for v in bm.verts if v.co.x > 0.5]

Ensure updates propagate

After bm.to_mesh(mesh):

mesh.update()
# If normals need recalculating:
mesh.calc_normals()   # or use bmesh.ops.recalc_face_normals before to_mesh

Add primitive shortcut (operator-based)

When you don't need full procedural control, primitives are fine in headless:

bpy.ops.mesh.primitive_cube_add(size=2.0, location=(0,0,0))
obj = bpy.context.active_object

Other: primitive_uv_sphere_add, primitive_cylinder_add, primitive_torus_add, primitive_monkey_add.