Skip to content

Options Classes

This page documents the options classes for configuring remeshing operations.

Overview

Each mesh kind has a corresponding options class:

Mesh Kind Options Class
TETRAHEDRAL Mmg3DOptions
TRIANGULAR_2D Mmg2DOptions
TRIANGULAR_SURFACE MmgSOptions

Options classes are immutable dataclasses with:

  • Type-checked parameters
  • IDE autocomplete support
  • Factory methods for common configurations
  • Conversion to dictionary for remesh()

3D Options

mmgpy.Mmg3DOptions dataclass 

Mmg3DOptions(
    *,
    hmin: float | None = None,
    hmax: float | None = None,
    hsiz: float | None = None,
    hausd: float | None = None,
    hgrad: float | None = None,
    hgradreq: float | None = None,
    ar: float | None = None,
    verbose: int | None = None,
    mem: int | None = None,
    optim: bool = False,
    noinsert: bool = False,
    noswap: bool = False,
    nomove: bool = False,
    nreg: bool = False,
    anisosize: bool = False,
    nosurf: bool = False,
    opnbdy: bool = False,
    nofem: bool = False,
    optim_les: bool = False,
)

Bases: _MmgOptionsBase

Options for 3D tetrahedral mesh remeshing (MMG3D).

All parameters are optional. When None, MMG uses its internal defaults. Options are immutable after creation.

Inherits from _MmgOptionsBase

hmin, hmax, hsiz, hausd, hgrad, hgradreq, ar, verbose, mem, optim, noinsert, noswap, nomove, nreg, anisosize

Additional Attributes

nosurf : bool Disable surface modifications (3D only). opnbdy : bool Preserve open boundaries (no closing at non-manifold edges). nofem : bool Skip the final FEM-friendly element-quality cleanup pass. optim_les : bool Optimize mesh for LES (Large-Eddy Simulation) anisotropic boundary layers.

Example:

opts = Mmg3DOptions(hmax=0.1, hausd=0.01) mesh.remesh(opts) # Pass options directly

nosurf class-attribute instance-attribute 

nosurf: bool = False

Disable surface modifications (3D only).

opnbdy class-attribute instance-attribute 

opnbdy: bool = False

Preserve open boundaries (no closing at non-manifold edges).

nofem class-attribute instance-attribute 

nofem: bool = False

Skip the final FEM-friendly element-quality cleanup pass.

optim_les class-attribute instance-attribute 

optim_les: bool = field(default=False, metadata={'mmg_name': 'optimLES'})

Optimize for LES anisotropic boundary layers.

__post_init__ 

__post_init__() -> None

Validate options after initialization.

options: show_root_heading: true members: - init - fine - coarse - optimize_only - to_dict

2D Options

mmgpy.Mmg2DOptions dataclass 

Mmg2DOptions(
    *,
    hmin: float | None = None,
    hmax: float | None = None,
    hsiz: float | None = None,
    hausd: float | None = None,
    hgrad: float | None = None,
    hgradreq: float | None = None,
    ar: float | None = None,
    verbose: int | None = None,
    mem: int | None = None,
    optim: bool = False,
    noinsert: bool = False,
    noswap: bool = False,
    nomove: bool = False,
    nreg: bool = False,
    anisosize: bool = False,
    nosurf: bool = False,
    opnbdy: bool = False,
    nofem: bool = False,
)

Bases: _MmgOptionsBase

Options for 2D triangular mesh remeshing (MMG2D).

All parameters are optional. When None, MMG uses its internal defaults. Options are immutable after creation.

Inherits from _MmgOptionsBase

hmin, hmax, hsiz, hausd, hgrad, hgradreq, ar, verbose, mem, optim, noinsert, noswap, nomove, nreg, anisosize

Additional Attributes

nosurf : bool Disable boundary modifications. opnbdy : bool Preserve open boundaries. nofem : bool Skip the final FEM-friendly element-quality cleanup pass.

nosurf class-attribute instance-attribute 

nosurf: bool = False

Disable boundary modifications.

opnbdy class-attribute instance-attribute 

opnbdy: bool = False

Preserve open boundaries.

nofem class-attribute instance-attribute 

nofem: bool = False

Skip the final FEM-friendly element-quality cleanup pass.

__post_init__ 

__post_init__() -> None

Validate options after initialization.

options: show_root_heading: true members: - init - fine - coarse - optimize_only - to_dict

Surface Options

mmgpy.MmgSOptions dataclass 

MmgSOptions(
    *,
    hmin: float | None = None,
    hmax: float | None = None,
    hsiz: float | None = None,
    hausd: float | None = None,
    hgrad: float | None = None,
    hgradreq: float | None = None,
    ar: float | None = None,
    verbose: int | None = None,
    mem: int | None = None,
    optim: bool = False,
    noinsert: bool = False,
    noswap: bool = False,
    nomove: bool = False,
    nreg: bool = False,
    anisosize: bool = False,
    keep_ref: bool = False,
)

Bases: _MmgOptionsBase

Options for surface mesh remeshing (MMGS).

All parameters are optional. When None, MMG uses its internal defaults. Options are immutable after creation.

Inherits from _MmgOptionsBase

hmin, hmax, hsiz, hausd, hgrad, hgradreq, ar, verbose, mem, optim, noinsert, noswap, nomove, nreg, anisosize

Note: Surface remeshing (MMGS) does not have a nosurf option.

Additional Attributes

keep_ref : bool Keep edge references in the output (forwarded as keepRef).

keep_ref class-attribute instance-attribute 

keep_ref: bool = field(default=False, metadata={'mmg_name': 'keepRef'})

Keep edge references in the output (forwarded as keepRef).

__post_init__ 

__post_init__() -> None

Validate options after initialization.

options: show_root_heading: true members: - init - fine - coarse - optimize_only - to_dict

Parameter Reference

Size Parameters

Parameter Type Description
hmin float Minimum edge length
hmax float Maximum edge length
hsiz float Uniform target edge length
hgrad float Gradation: max ratio between adjacent edges (default: 1.3)

Geometric Parameters

Parameter Type Description
hausd float Hausdorff distance: max distance to input geometry
angle float Ridge detection angle in degrees (default: 45.0)

Control Parameters

Parameter Type Description
optim bool Optimize element quality without other topology changes
optim_les bool (3D only) Optimize for LES anisotropic boundary layers (optimLES)
noinsert bool Disable vertex insertion (no new vertices)
nosurf bool (3D / 2D) Preserve surface or boundary, don't move them
nomove bool Disable vertex motion (no smoothing)
noswap bool Disable edge swapping (no topology changes)
opnbdy bool (3D / 2D) Preserve open boundaries / non-manifold edges
nofem bool (3D / 2D) Skip the final FEM-friendly element-quality cleanup pass
nreg bool Use vertex normals to smooth the mesh (normal regularization)
anisosize bool Treat the size map as anisotropic (otherwise treated as isotropic)
keep_ref bool (Surface only) Keep edge references in the output (keepRef)

Niche Parameters (kwargs only)

These are accepted as keyword arguments to remesh(...) but are not exposed as fields on the dataclasses:

Parameter Mesh kinds Description
octree 3D Octree-based search (advanced)
numsubdomain all Restrict remeshing to a subdomain by reference
isoref all Reference value for the implicit-domain interface
nosizreq all Disable required-entity size enforcement
xreg all Enable coordinate-field regularization
xreg_val all Strength of xreg regularization
rmc all Remove small connected components (level-set mode)
3dmedit 2D Toggle the 3D-Medit file-format flag

Output Parameters

Parameter Type Description
verbose int Verbosity: -1=silent, 0=errors, 1=info, 2+=debug

Usage Examples

Basic Usage

import pyvista as pv
import mmgpy  # noqa: F401  -- registers reader/writer + accessor
from mmgpy import Mmg3DOptions

mesh = pv.read("input.mesh")

opts = Mmg3DOptions(
    hmin=0.01,
    hmax=0.1,
    hausd=0.001,
    verbose=1,
)

remeshed = mesh.mmg.remesh(opts)

Factory Methods

from mmgpy import Mmg3DOptions

# Fine mesh (small elements)
fine_opts = Mmg3DOptions.fine(hmax=0.01)

# Coarse mesh (large elements)
coarse_opts = Mmg3DOptions.coarse(hmax=1.0)

# Optimization only (no topology changes)
opt_opts = Mmg3DOptions.optimize_only()

Converting to Dictionary

opts = Mmg3DOptions(hmax=0.1, hausd=0.001)

# Get as dictionary
params = opts.to_dict()
print(params)  # {'hmax': 0.1, 'hausd': 0.001}

# Unpack into remesh
remeshed = mesh.mmg.remesh(**opts.to_dict())

Customizing Presets

# Start with fine preset values, then customize
custom = Mmg3DOptions(hmax=0.05, hausd=0.01, hgrad=1.2, verbose=1)

Combining with Keyword Arguments

Options objects and keyword arguments cannot be mixed:

# Correct: use options object
remeshed = mesh.mmg.remesh(opts)

# Correct: use keyword arguments
remeshed = mesh.mmg.remesh(hmax=0.1, hausd=0.001)

# Error: mixing both
remeshed = mesh.mmg.remesh(opts, verbose=1)  # TypeError!

For Quality Optimization

opts = Mmg3DOptions(
    optim=1,       # Enable optimization mode
    noinsert=1,    # Don't add vertices
    hgrad=1.1,     # Gentle gradation
)

For Surface Preservation

opts = Mmg3DOptions(
    hmax=0.1,
    hausd=0.0001,  # Tight approximation
    nosurf=1,      # Preserve surface vertices
)

For CFD Meshes

opts = Mmg3DOptions(
    hmin=0.001,
    hmax=0.1,
    hgrad=1.2,     # Smooth size transition
    hausd=0.001,
    ar=20,       # Detect more ridges
)

For FEM Meshes

opts = Mmg3DOptions(
    hmin=0.01,
    hmax=0.1,
    hgrad=1.3,
    verbose=1,
)