pyvista_js.PolyData.contour

pyvista_js.PolyData.contour#

PolyData.contour(isosurfaces: int | list[float] = 10, scalars: ArrayLike | None = None, scalar_name: str | None = None) → PolyData#

Generate contour lines at constant scalar values.

This filter extracts isolines from the mesh at specified scalar values using a marching triangles algorithm implemented in JavaScript. It mirrors the PyVista contour filter API.

Note

The contour is computed in JavaScript at render time by applying the marching triangles algorithm to each triangle of the mesh, interpolating edge crossings at the specified iso-values. vtk.js does not support vtkPolyData input for vtkContourFilter, so this filter is implemented as a custom JavaScript pass.

Parameters:

  • isosurfaces (int or list of float, optional) – Number of evenly spaced contours to generate, or a list of explicit scalar values at which to generate contours. Default is 10.

  • scalars (array-like, optional) – Scalar values per point to use for contouring. If not provided, uses the mesh’s existing scalars attribute. Must have length equal to n_points.

  • scalar_name (str, optional) – Name for the scalar array in vtk.js. If not provided, uses the mesh’s existing scalar_name attribute or defaults to “scalars”.

Returns:

A new mesh containing the contour lines.

Return type:

PolyData

Raises:

ValueError – If no scalars are provided and the mesh has no scalar data, or if isosurfaces parameter is invalid.

Examples

>>> import pyvista_js as pv
>>> sphere = pv.Sphere()
>>> sphere_scalars = sphere.points[:, 2]
>>> contours = sphere.contour(isosurfaces=5, scalars=sphere_scalars)
>>> isinstance(contours, pv.PolyData)
True

Generate contours at specific values:

>>> contours = sphere.contour(isosurfaces=[-0.5, 0.0, 0.5], scalars=sphere_scalars)

Render the contours:

>>> contours.plot()
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