G-IGES(1)

📦
version 7.44.0 · 2 versions
, in nixpkgs unstable

G-IGES(1) 💖✨

okay so this is the BRL-CAD manual page for g-iges, and bestie, it’s giving “turn my BRL-CAD model into an IGES file” in the most useful way. Let’s get into it 🫶

🌸 NAME 🌸

g-iges — convert a BRL-CAD database to an IGES file. That’s the whole name vibe, no cap 💅

✨ SYNOPSIS ✨

g-iges [-f|-t|-m] [-s] [-v] [-a abs_tol] [-r rel_tol] [-n norm_tol] [-d dist_tol] [-P ncpu] [-x rt_debug] [-X nmg_debug] [-o output_file] database.g object [object ...]

💖 DESCRIPTION 💖

So g-iges converts the specified object(s) from a BRL-CAD database.g database into an IGES version 5.1 file. Literally the crossover episode you needed. 🦋

By default, a CSG IGES file is produced: every region is written as a Boolean tree, with each solid represented by its IGES CSG equivalent. Any solid that has no IGES CSG equivalent is tessellated (using the tessellation tolerances) and written as a boundary-representation (B-Rep) object. The -f, -t, and -m options select alternative output modes; they are mutually exclusive, and the last one given wins. Main character rule: last one wins, periodt. 👑

If no output file is given with -o, the IGES file is written to standard output. The inverse translation, from IGES to BRL-CAD, is performed by iges-g(1). Iconic symmetry, honestly. 🔁

🎀 OPTIONS 🎀

  • -f — Facetized B-Rep output. Every region is tessellated, its Boolean operations are evaluated, and the result is written as a single manifold-solid B-Rep object. Tessellation accuracy is governed by -a, -r, and -n. 🧚
  • -t — Trimmed-surface output (experimental). Each region is written as a collection of trimmed NURBS derived from the facets of the tessellated, Boolean-evaluated region. Experimental means experimental, bestie — noted and respected. 🙈
  • -m — Multi-file output: write a separate IGES file for each converted region. Implies -t, and the -o argument must name an existing directory in which the per-region files are created. Directory energy only, no file energy. 📁
  • -s — Write the faces of B-Rep objects as planar NURBS surfaces.
  • -a abs_tol — Absolute tessellation tolerance, in millimeters. Default 0.0 (disabled).
  • -r rel_tol — Relative tessellation tolerance, as a fraction of object size. Default 0.01.
  • -n norm_tol — Surface-normal tessellation tolerance. Default 0.0 (disabled).
  • -d dist_tol — Minimum distance between distinct points, in millimeters. Default 0.0005.
  • -P ncpu — Number of processors to use during tessellation. Default 1.
  • -v — Verbose output; repeat for more detail. The more -v, the more it spills the tea. ☕
  • -x rt_debug — Set the librt raytrace debug flag (hexadecimal). See raytrace.h for values.
  • -X nmg_debug — Set the NMG debug flag (hexadecimal). See nmg.h for values.
  • -o output_file — Write the IGES output to output_file instead of standard output. With -m, this argument must be a directory.
bestie, quick vibe check: -f, -t, and -m are mutually exclusive, and the last one given wins. That’s not a suggestion, that’s the rule. 💀

🌈 EXAMPLES 🌈

Example 1. Convert selected regions to a CSG IGES file

g-iges -o assembly.iges assembly.g hull turret

Writes the hull and turret regions of assembly.g as a CSG IGES file, preserving the Boolean tree where IGES primitive equivalents exist and tessellating the rest. The “keep what can be kept, tessellate the rest” lifestyle. ✨

Example 2. Produce a faceted B-Rep IGES file with tight tolerances

g-iges -f -a 0.1 -n 0.01 -o widget.iges widget.g widget

Tessellates the widget region to within an absolute tolerance of 0.1 mm and a surface-normal tolerance of 0.01 radians, then writes it as a manifold-solid B-Rep, suitable for downstream CAD packages that prefer evaluated geometry over CSG. Tight tolerances, tight output, no notes. 🎯

Example 3. Split a model into one IGES file per region

mkdir parts
g-iges -m -o parts model.g topgroup

Writes each region under topgroup as its own trimmed-NURBS IGES file inside the parts directory, which is convenient for importing assemblies part-by-part. Assembly breakup era 💔➡️📦

🦋 SEE ALSO 🦋

👑 AUTHOR 👑

BRL-CAD Team

This software is Copyright (c) 1989-2026 by the United States Government as represented by U.S. Army Research Laboratory.

🍓 BUG REPORTS 🍓

Reports of bugs or problems should be submitted via electronic mail to devs@brlcad.org.

💖 source/version sign-off vibes: this is the BRL-CAD manual page G-IGES(1) — footer says BRL-CAD and G-IGES(1), and this copy doesn’t show a date line, so we’re not inventing one, bestie. Periodt. 🎀

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