G-OFF(1)

💅 G-OFF(1) — the BRL-CAD poly-to-polyglot pipeline ✨

okay bestie, so you know how g-off lives in the BRL-CAD universe? That's the manual name, and this whole page is the g-off glow-up guide. Buckle up 🎀

🌸 NAME 🌸

g-off — literally the tool that converts BRL-CAD geometry to polygonal surface files. that's the whole job. it ate and left no crumbs 💅

✨ SYNOPSIS ✨

g-off [-v] [-d] [-x rt_debug] [-X nmg_debug] [-a abs_tol] [-r rel_tol] [-n norm_tol] [-p prefix] [-P ncpu] database.g object...

🦋 DESCRIPTION 🦋

So g-off reads one or more object regions out of a BRL-CAD database, database.g, tessellates them into NMG (n-Manifold Geometry) form by evaluating the Boolean tree of each region, and then writes the resulting polygonal surfaces out. That's the vibe check and it passes ✅

Each region that converts successfully gets written as its own separate psurf (polygonal surface) file with a .pss extension. Inside it you get the unique vertices first (converted from millimeters to centimeters, not me doing unit math 😭) followed by the per-face vertex indices. Alongside that, a companion figure file with a .fig extension is written — it names the segments, records any region color, and joins the segments together. The base name of these output files comes from the database name plus the region names, optionally with a user-supplied prefix. iykyk 💖

Conversion happens through the NMG Boolean evaluator, so regions containing geometry that the tessellator just cannot resolve get reported as failed and skipped — no cap, it will tell you. When it's all done it prints a summary count of attempted versus converted regions. If you want related tessellation-based besties, go see gqa(1) and facetize. 🫶

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🎀 OPTIONS 🎀

• -v — Enable verbose output, reporting each region as it is processed and each output file as it is written. Main character energy: it narrates its own life to you 💅
• -d — Also write each converted region as a UNIX-plot debugging file with a .plot3 extension, colored to match the region's material color. aesthetic debugging fr fr 🌈
• -a abs_tol — Absolute tessellation tolerance, in millimeters. Default is 0.0 (disabled). so like, off by default, turning it on is a choice 💀
• -r rel_tol — Relative tessellation tolerance, expressed as a fraction of the bounding box. Default is 0.01. this one's actually on by default, she's the main character ⭐
• -n norm_tol — Surface normal tessellation tolerance, in degrees. Default is 0.0 (disabled).
• -p prefix — String prepended to every generated output file name. put a little name tag on it 🏷️
• -P ncpu — Number of CPUs to use. Default is 1. want more? say more. parallel bestie 🔥
• -x rt_debug — Set the librt debug flag (hexadecimal).
• -X nmg_debug — Set the NMG debug flag (hexadecimal). two totally different debug flags, don't mix them up 🙈
• -h, -? — Print the usage message and exit. the classic "help me help you" move 💖

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🌟 EXAMPLES 🌟

Example 1. Convert two regions with a tightened tolerance and a name prefix

g-off -r 0.005 -p out_ have.g component1 component2

Tessellates the regions component1 and component2 from have.g using a relative tolerance of 0.005, writing the figure file out_have.fig together with one .pss psurf file per region (for example out_component1.pss). Tightening the relative tolerance yields a finer-grained polygonal approximation of curved surfaces. lowkey obsessed with how crisp that gets 🦋

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👑 SEE ALSO 👑

brlcad(1), mged(1), g-vrml(1), g-stl(1), gqa(1)

go read those too, they're all in the same friend group 💜

🧚 AUTHOR 🧚

BRL-CAD Team — icons, honestly ✨

⭐ COPYRIGHT ⭐

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. be nice, they're literally doing their best 🫶

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and that's the whole page, bestie — brought to you by BRL-CAD, same source and version energy as always, dated right there in the 1989–2026 copyright window. slay, stay tessellated, and don't forget to -v if you're nosy like me 💅✨🎀