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.. _tut_polyface:
Tutorial for Polyface
=====================
The :class:`~ezdxf.entities.Polyface` entity represents a 3D mesh build of
vertices and faces and is just an extended POLYLINE entity with a complex
VERTEX structure. The :class:`Polyface` entity was used in DXF R12 and older
DXF versions and is still supported by newer DXF versions. The new
:class:`~ezdxf.entities.Mesh` entity stores the same data much more efficient
but requires DXF R2000 or newer. The :class:`Polyface` entity supports only
triangles and quadrilaterals as faces, the :class:`Mesh` entity supports also
n-gons.
Its recommended to use the :class:`~ezdxf.render.MeshBuilder` objects to
create 3D meshes and render them as POLYFACE entities by the
:meth:`~ezdxf.render.MeshBuilder.render_polymesh` method into a layout:
.. code-block:: Python
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")
.. image:: gfx/mesh_cubes.png
.. warning::
If the mesh contains n-gons the render methods for POLYFACE and
3DFACES subdivides the n-gons into triangles, which does **not** work for
concave faces.
The usage of the :class:`~ezdxf.render.MeshBuilder` object is also recommended
for inspecting :class:`Polyface` entities:
- :attr:`MeshBuilder.vertices` is a sequence of 3D points as
:class:`ezdxf.math.Vec3` objects
- a face in :attr:`MeshBuilder.faces` is a sequence of indices into the
:attr:`MeshBuilder.vertices` sequence
.. code-block:: Python
import ezdxf
from ezdxf.render import MeshBuilder
def process(mesh):
# vertices is a sequence of 3D points
vertices = mses.vertices
# a face is a sequence of indices into the vertices sequence
faces = mesh.faces
...
doc = ezdxf.readfile("meshes.dxf")
msp = doc.modelspace()
for polyline in msp.query("POLYLINE"):
if polyline.is_poly_face_mesh:
mesh = MeshBuilder.from_polyface(polyline)
process(mesh)
.. seealso::
:ref:`tut_mesh`
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