Tutorial for Mesh

The Mesh entity is a 3D object in WCS build up from vertices and faces.

Create a cube mesh by directly accessing the base data structures:

import ezdxf


# 8 corner vertices
cube_vertices = [
    (0, 0, 0),
    (1, 0, 0),
    (1, 1, 0),
    (0, 1, 0),
    (0, 0, 1),
    (1, 0, 1),
    (1, 1, 1),
    (0, 1, 1),
]

# 6 cube faces
cube_faces = [
    [0, 1, 2, 3],
    [4, 5, 6, 7],
    [0, 1, 5, 4],
    [1, 2, 6, 5],
    [3, 2, 6, 7],
    [0, 3, 7, 4]
]

# MESH requires DXF R2000 or later
doc = ezdxf.new("R2000")
msp = doc.modelspace()
mesh = msp.add_mesh()
# do not subdivide cube, 0 is the default value
mesh.dxf.subdivision_levels = 0
with mesh.edit_data() as mesh_data:
    mesh_data.vertices = cube_vertices
    mesh_data.faces = cube_faces

doc.saveas("cube_mesh_1.dxf")

Create a cube mesh by assembling single faces using the edit_data() context manager of the Mesh class and the helper class MeshData:

import ezdxf


# 8 corner vertices
p = [
    (0, 0, 0),
    (1, 0, 0),
    (1, 1, 0),
    (0, 1, 0),
    (0, 0, 1),
    (1, 0, 1),
    (1, 1, 1),
    (0, 1, 1),
]

# MESH requires DXF R2000 or later
doc = ezdxf.new("R2000")
msp = doc.modelspace()
mesh = msp.add_mesh()

with mesh.edit_data() as mesh_data:
    mesh_data.add_face([p[0], p[1], p[2], p[3]])
    mesh_data.add_face([p[4], p[5], p[6], p[7]])
    mesh_data.add_face([p[0], p[1], p[5], p[4]])
    mesh_data.add_face([p[1], p[2], p[6], p[5]])
    mesh_data.add_face([p[3], p[2], p[6], p[7]])
    mesh_data.add_face([p[0], p[3], p[7], p[4]])
    # optional call optimize(): minimizes the vertex count
    mesh_data.optimize()

doc.saveas("cube_mesh_2.dxf")

Its recommended to use the MeshBuilder objects to create 3D meshes and render them as MESH entities by the render_mesh() method into a layout:

import ezdxf
from ezdxf import colors
from ezdxf.gfxattribs import GfxAttribs
from ezdxf.render import forms

cube = forms.cube().scale_uniform(10).subdivide(2)
red = GfxAttribs(color=colors.RED)
green = GfxAttribs(color=colors.GREEN)
blue = GfxAttribs(color=colors.BLUE)

doc = ezdxf.new()
msp = doc.modelspace()

# render as MESH entity
cube.render_mesh(msp, dxfattribs=red)
cube.translate(20)

# render as POLYFACE a.k.a. POLYLINE entity
cube.render_polyface(msp, dxfattribs=green)
cube.translate(20)

# render as a bunch of 3DFACE entities
cube.render_3dfaces(msp, dxfattribs=blue)

doc.saveas("meshes.dxf")

There exist some tools to manage meshes:

ezdxf.render.MeshBuilder: The MeshBuilder classes are helper tools to manage meshes buildup by vertices and faces.
ezdxf.render.MeshTransformer: Same functionality as MeshBuilder but supports inplace transformation.
ezdxf.render.MeshDiagnose: A diagnose tool which can be used to analyze and detect errors of MeshBuilder objects like topology errors for closed surfaces.
ezdxf.render.FaceOrientationDetector: A helper class for face orientation and face normal vector detection

The ezdxf.render.forms module provides function to create basic geometries like cube, cone, sphere and so on and functions to create meshes from profiles by extrusion, rotation or sweeping.

This example shows how to sweep a gear profile along a helix:

import ezdxf
from ezdxf.render import forms

doc = ezdxf.new()
doc.layers.add("MESH", color=ezdxf.colors.YELLOW)
msp = doc.modelspace()
# sweeping a gear-profile
gear = forms.gear(
    8, top_width=0.01, bottom_width=0.02, height=0.02, outside_radius=0.1
)
helix = path.helix(radius=2, pitch=1, turns=6)
# along a helix spine
sweeping_path = helix.flattening(0.1)
mesh = forms.sweep(gear, sweeping_path, close=True, caps=True)
# and render as MESH entity
mesh.render_mesh(msp, dxfattribs={"layer": "MESH"})
doc.saveas("gear_along_helix.dxf")