// read_anything()

ONE LINE IN.
ANY MESH OUT.

Reading 3D meshes in Python normally means installing one library per format. polyxios is a single small, maintained package that reads and writes all twenty-five — and raises instead of quietly corrupting your data.

$ pip install polyxios docs() -> formats() ->

25formats

1dependency

0silent truncations

mmaplazy reads

read_write.py— □ ×

import polyxios as px

mesh = px.read("brain.vtk")
mesh.vertices.shape        # (n, 3)
len(mesh.element_types)     # 2

px.write(mesh, "brain.ply")
px.write(mesh, "brain.stl", binary=True)

# gigabytes? memory-map it
mesh = px.read("huge.vtk", lazy=True)█

01 // formats

supported_extensions()

Every format carries its own page: what the specification says, what polyxios does with it, and a link to the authoritative document.

formatextreadwritelazy

VTK Legacy.vtk[x][x]mmap: binary VTK RectilinearGrid.vtr[x][x]- - - - VTK PolyData.vtp[x][x]- - - - Wavefront OBJ.obj[x][x]- - - - Stanford PLY.ply[x][x]mmap: binary STL.stl[x][x]mmap: binary OFF.off[x][x]- - - - Abaqus.inp[x][x]- - - - AVS-UCD.avs[x][x]- - - - Medit binary.meshb[x][x]mmap: binary DOLFIN / FEniCS XML.xml[x][x]- - - - FLAC3D.f3grid[x][x]- - - - Gmsh.msh[x][x] v2 only- - - - Nastran.bdf .nas .fem[x][x]- - - - Tecplot ASCII.tec[x][x]- - - - SU2.su2[x][x]- - - - TetGen.ele + .node[x][x]- - - - Well-Known Text.wkt[x][x]- - - - VTK UnstructuredGrid.vtu[x][x]- - - - VTK StructuredGrid.vts[x][x]- - - - VTK ImageData.vti[x][x]- - - - MFEM mesh.mesh[x][x]- - - - Netgen.vol[x][x]- - - - UGRID (AFLR).ugrid[x][x]- - - - Gaussian splat.splat[x][x]- - - -

} // 25 codecs, 34 extensions

02 // guarantees

assert not corrupted

[00]

No silent corruption

Large mesh indices raise an error instead of quietly truncating to a narrower integer.

[01]

Groups preserved

A face belonging to several tags stays in all of them, through a full read-write round trip.

[02]

Safe on untrusted files

Header counts are validated before any memory is allocated for the body.

[03]

No compiler needed

Pure Python fallbacks ship with the package; the Cython hot-paths are optional.

03 // cli

$ pxios

Ships with the package. Pull a catalogued model, convert it, and render it through FURY without writing a script.

list: remote catalogue, local cache, or codecs
fetch: one file, or every model for an extension
convert: format to format in a single process
viz: surface, --lines or --points

bash — 80×24

$ pxios fetch bunny.obj
  cached -> ~/.polyxios/bunny.obj  (2.9 MB)

$ pxios convert bunny.obj bunny.vtk
  35947 vertices · 69451 triangles · 0.4s

$ pxios list --codecs
  .avs .bdf .ele .f3grid .inp .meshb .msh
  .obj .off .ply .stl .su2 .tec .vtk .vtp
  .vtr .wkt .xml

$ pxios viz bunny.vtk --points█

04 // plugins

register() -> ".abc"

Any third-party package can teach polyxios a nineteenth format. Two functions and an entry point — no fork, no pull request, no restart.

step 01 — mypackage/abc_codec.py

from polyxios._registry import Codec

def read(path, *, lazy=False): ...
def write(poly, path, **opts): ...

def register():
    return ".abc", Codec(read, write)

step 02 — pyproject.toml

[project.entry-points."polyxios.codecs"]
abc = "mypackage.abc_codec:register"

# then, anywhere:
mesh = px.read("model.abc")
# picked up automatically

Full plugin guide ->