TikZ (.tikz)

TikZ/PGF output for 2D meshes — a write-only visualization format that draws the mesh cells as a LaTeX figure. By default it emits a standalone, directly pdflatex-compilable document; it can also emit a bare tikzpicture snippet for \input into a larger LaTeX document. It is the LaTeX counterpart to the SVG writer.

Format name	tikz
Extensions	.tikz
Read / Write	— / ✓
Extra dependencies	—

Reading & writing

There is no reader — register_format is called with read=None. Full write signature:

import meshioplusplus

meshioplusplus.tikz.write(
    "out.tikz", mesh,
    float_fmt=".6f",
    standalone=True,
    line_width=None,
    fill="gray!30",
    draw="black",
    scale=None,
)

• float_fmt — coordinate number format.
• standalone — if True (default), wrap the tikzpicture in a full \documentclass{standalone} + \usepackage{tikz} document that compiles directly with pdflatex. If False, emit only the \begin{tikzpicture}…\end{tikzpicture} environment for \input into an existing document.
• line_width — TikZ line width for edges, e.g. "0.4pt"; if None (default), TikZ's own default width is used. When set it is applied both on the tikzpicture options and on each \draw.
• fill — xcolor fill spec for the filled faces (triangles/quads), e.g. "gray!30", "blue!20".
• draw — xcolor spec for the edge stroke.
• scale — optional \begin{tikzpicture}[scale=…] factor; if None (default), coordinates are emitted verbatim and no scale key is added.

File structure

One \draw command per drawable cell inside a single tikzpicture environment. Each cell's vertices are emitted as (x,y) coordinate pairs (float_fmt-formatted) joined by TikZ's -- path operator:

cell type	\draw template
line	\draw[draw=…] (x0,y0) -- (x1,y1); (open, no cycle)
triangle	\draw[fill=…, draw=…] (x0,y0) -- (x1,y1) -- (x2,y2) -- cycle;
quad	\draw[fill=…, draw=…] (x0,y0) -- (x1,y1) -- (x2,y2) -- (x3,y3) -- cycle;

Points must be flat 2D: if points.shape[1] == 3, every z coordinate must be ~0 (atol=1e-14), else WriteError. Only the first two columns are used.

Unlike the SVG writer, the y-coordinate is not flipped — TikZ/PGF already uses the math convention (y grows upward), so mesh coordinates map straight onto the canvas.

Cell types

line, triangle, quad only. Any other cell block present in the mesh is silently dropped (matching the SVG writer's behaviour).

Data mapping

None consumed — point_data/cell_data/field_data are ignored entirely; only geometry and cell connectivity affect the output.

Quirks & limitations

• No winding correction on quad cells — a "crossed" (bowtie) node ordering renders incorrectly with no error raised.
• Non-line/triangle/quad cells vanish from the output silently.
• Write-only; there is no way to read a TikZ figure back into a Mesh.

Notes

• Backed by the C++ core (write_tikz) with a pure-Python fallback: meshioplusplus.tikz.write uses the C++ writer for real file paths and falls back to Python for file-object/buffer targets or on any error. The C++ writer is byte-for-byte identical to the Python reference. Registered in the shared dispatch registry, so it is also reachable from the WASM, C API, and Fortran flat bindings (write-only, fixed default styling; the flat surface always emits the standalone document).
• tests/test_tikz.py checks the document/tikzpicture wrappers and \draw count, cross-checks the C++ and Python writers are byte-identical, and covers the standalone=False snippet and the non-flat-3D WriteError path. cpp/tests/test_svg_tikz.cpp covers the C++ writer directly (standalone vs snippet, filled faces vs open lines, \draw count, style/scale options, the non-flat WriteError).