JACK-G(1)

📦 version 7.44.0, in nixpkgs unstable

✨ JACK-G(1) ✨

Okay so bestie, let me put you onto jack-g — it’s literally the main character of Psurf-to-BRL-CAD conversions, no cap. Periodt.

🌸 SYNOPSIS 🌸

jack-g [-r region] [-g group] [jack_db] [brlcad_db]

💖 DESCRIPTION 💖

So jack-g converts a Jack Psurf (.pss) file into a BRL-CAD database (.g). The way it does this is kind of iconic: it reads the polygonal surface geometry from the Psurf file into an n-Manifold Geometry (NMG) model, and then writes that out as a BOT (Bag of Triangles) object wrapped in a region. And not me noticing that coordinates get scaled from centimeters to millimeters during conversion — like, she’s precise, okay? 💅

Jack, for the uninitiated, originally came from the University of Pennsylvania's Computer Graphics Research Laboratory. It’s a package for human figure animation and ergonomic analysis (later developed commercially as Tecnomatix Jack). Very “I was in academia before it was cool” energy.

The Jack Psurf file is read from jack_db, or from standard input if no input file is given (or if jack_db is given as -). The resulting geometry is written to the BRL-CAD database named brlcad_db, which is required — like, you literally cannot skip it, bestie. For each surface, a solid named s.region, a region named r.region, and optionally a group are created.

🎀 OPTIONS 🎀

  • -r region — This names the BRL-CAD region created for the converted surface. If you don’t specify it, the region name is derived from the input file name (with any leading path and trailing .pss extension removed). Lowkey convenient, highkey slay.
  • -g group — Adds the converted region to a BRL-CAD group of this name, creating the group if necessary. So you can organize your geometry like the responsible icon you are. Iykyk.
  • -h, -? — Prints a usage message and exits. Standard behavior, but still giving “I’m helpful” realness.

🦋 EXAMPLES 🦋

Example 1. Convert a Jack human figure into a named region and group

jack-g -r torso -g body torso.pss model.g

This reads the Jack Psurf file torso.pss, writes a BOT solid s.torso inside region r.torso into model.g, and adds that region to the group body. The resulting model.g can then be raytraced with rt(1) or inspected interactively with mged(1). Not me being obsessed with this whole workflow. 😭🔥

Example 2. Convert geometry piped from standard input

cat figure.pss | jack-g -r figure model.g

This reads the Psurf data from standard input, which is useful when the geometry is produced by another tool in a pipeline rather than stored on disk. So if you’re the kind of person who pipes things through a pipeline, this is your moment. 🌈

🌟 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

And that’s the whole vibe, bestie. This page is from BRL-CAD (source) and honestly it’s giving 1989-2026 legacy energy. Stay slaying. 🫶💅✨

📦 where this page comes from