G-JACK(1)

📦 version 7.44.0, in nixpkgs unstable

💖 NAME — g-jack (G-JACK(1)) 💖

okay so bestie, g-jack is the main-character command that converts a BRL-CAD model to Jack Psurf (.pss) and figure (.fig) files. That's the G-JACK(1) manual, and we're gonna get you comfy with it. 💅

✨ SYNOPSIS ✨

g-jack [-v] [-d] [-f] [-x _rt_debug_] [-X _nmg_debug_] [-u _eu_dist_] [-a _abs_tess_tol_] [-r _rel_tess_tol_] [-n _norm_tess_tol_] [-D _dist_calc_tol_] [-p _prefix_] [-P _ncpu_] _database.g_ _object(s)_...

🌸 DESCRIPTION 🌸

g-jack converts the specified object(s) from a BRL-CAD database database.g into the Jack Psurf format used by the Jack human figure animation and ergonomic analysis package (originally from the University of Pennsylvania, later the commercial Tecnomatix Jack from Siemens). iykyk, it's giving legacy-but-iconic.

Each region is tessellated through the NMG boolean evaluator and written to its own polygonal surface file with a .pss suffix; the file name is derived from the region's leaf object name with periods replaced by underscores (Jack's Peabody language disallows periods). So yes, those periods become underscores, no cap. 🫶

A single Jack figure file with a .fig suffix is also produced, named after database.g, that references every .pss segment, records material colors, and connects the segments with joints. Coordinates are converted from millimeters to centimeters on output. metric glow-up, honestly.

💅 OPTIONS 💅

  • -v — Enable verbose progress reporting. chatty terminal era.
  • -d — Also write a UNIX-plot debugging file (.plot3) for each converted region. debug girlie behavior, and we respect it.
  • -f — Suppress writing of the per-region .pss output files; the .fig file is still produced. Useful for checking that the geometry converts without generating output.
  • -u eu_dist — Set the edgeuse distance tolerance used for visualization (default 2.0).
  • -a abs_tess_tol — Set the absolute tessellation tolerance in millimeters.
  • -r rel_tess_tol — Set the relative tessellation tolerance (default 0.01).
  • -n norm_tess_tol — Set the surface normal tessellation tolerance.
  • -D dist_calc_tol — Set the calculation distance tolerance in millimeters used when deciding whether vertices are coincident (default 0.0005).
  • -p prefix — Prepend prefix to every generated output file name. name-brand your outputs, slay.
  • -P ncpu — Set the number of processors to use (default 1).
  • -x rt_debug — Set the librt debug flag (hexadecimal).
  • -X nmg_debug — Set the NMG debug flag (hexadecimal).

🎀 EXAMPLES 🎀

Example 1. Convert selected regions and inspect them

g-jack -p model_ -v -r 0.005 mannequin.g torso left_arm right_arm

Tessellates the three named regions from mannequin.g using a tighter relative tolerance, writing verbose progress to the terminal. The output files are named with the model_ prefix (for example model_torso.pss) and a model_mannequin.fig figure file is produced that ties the segments together for loading into Jack. obsessed with a clean little pipeline. ✨

🦋 SEE ALSO 🦋

👑 AUTHOR 👑

BRL-CAD Team. shoutout to the authors, the icons who made the manual page happen. 👑

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

signed off with 💖 by BRL-CAD — this is the G-JACK(1) page, with the copyright dates 1989–2026 doing their little date moment at the end. 🎀

📦 where this page comes from