Plotting

A 3D result cut by a plane, and the field in the cut A constraint sketch on the solid it lies on Example Airplane windows: where the stress collects

planex2d draws its objects with matplotlib or plotly, every edge from its exact curve. px.Plot takes faces, shapes, wires, compounds and sketches, and in Jupyter, every object shows itself as an SVG picture without a call. px.Plot3d draws the objects on their planes in 3D, next to OpenCASCADE solids.

A plot is also a check of the geometry. Marks show tiny edges, open ends and chosen edges, line_col="type" gives lines, arcs and splines a color each, and a sketch is drawn in the colors of its constraint state. px.PlotField draws measurements and simulation results from NGSolve or FEniCSx on the same geometry, from wall thickness maps to temperatures with contours, arrows and field lines.

In this section

General

matplotlibPlot returns the Axes, for several objects in one figure, panels and saving.

plotlyInteractive plots to zoom and pan, saved as HTML.

SVGThe picture Jupyter shows, as text, with arcs as exact SVG arcs.

Marking edgesMarking tiny edges, open ends and chosen edges, and coloring by the edges' own colors.

In 3DPlot3d draws planex2d objects on their planes in 3D, together with OpenCASCADE shapes.

Sketches

Sketch plotsConstraint states and signs, ends, directions, the solid below, and ids on hover.

Measurements and fields

MeasurementsThickness maps over faces and edges, and drawing measurements of your own.

FieldsNGSolve and FEniCSx results drawn the same way, with contours, arrows and field lines.

Everything at a glance

px.Plot option
obj	A face, shape, wire, compound, sketch or selection, an id that names one such as "Sketch.1", or an OpenCASCADE shape.
plane	For an OpenCASCADE shape: the plane it is cut at (see A section through a solid); without one, it is drawn flat in its own plane.
ax	A matplotlib Axes or plotly Figure to draw into; it also selects the backend.
backend	"matplotlib" (default) or "plotly".
line_col	The color of every edge. "type" draws lines in black, arcs in arc_col and splines in spline_col, each with a legend entry; "property" uses each edge’s own col.
face_col	The fill color of the faces (default #dde6f0); None draws the outlines only.
mark_edges_smaller, mark_free_edges	Marks short edges and edges with an open end at their midpoints.
highlight	Marks chosen edges, given as ids, selected edges or faces, indices or a mask.
legend	Shows the legend.
show_constraints, show_ends, show_direction	For a sketch: constraint signs, start and end pieces, and direction arrows.
show_parent	For a sketch: the OpenCASCADE solid it lies on, projected under it (see On a solid).

Fields and meshes
px.PlotField(field, mesh, obj)	Color maps of NGSolve and FEniCSx fields or of measurements, with the options on, vectors, field_lines, contours, min, max, colormap and samples.
px.PlotMesh(mesh, obj)	The element edges of a mesh, or of a cut through a 3D mesh.

See Fields and Measurements for drawing fields and measurements, and NGSolve and FEniCSx for the solvers.

Jupyter displays a plot by itself. In a script, plt.show() from matplotlib.pyplot opens the window.