GDIFF(nged)

✨ NAME ✨

okay so bestie, welcome to GDIFF(nged) — she lives in the BRL-CAD User Commands manual family 💅. gdiff is a BRL-CAD differential geometry comparator, and that’s the name-section tea. 🫖

🛠️ SYNOPSIS 🛠️

gdiff [options]... left_object right_object

💖 DESCRIPTION 💖

gdiff compares BRL-CAD geometry objects using LIBRT’s solid raytracing capabilities and visualizes differences in the display manager. It’s giving geometry detective with main character energy, fr fr. 🔍✨

Here’s the segment color lore:

• Red segments are the ones generated only from intersections with the left_obj object.
• Blue segments represent intersections unique to the right_obj object.
• White segments represent intersections common to both objects.

By default, only segments unique to the left and/or right objects are displayed. No extra noise, just the differences. 💅

Now, grid size is the thing you need to pay attention to, bestie. By default, gdiff will try to guess a reasonable grid spacing using the bounding boxes of the objects in question — but depending on the visual quality of the result, you may want to adjust the spacing up or down. 🎚️

⚠️ Be careful of specifying tolerances that are too fine — performance will drop off rapidly as grid spacing becomes very small. Like, dramatically. Don’t do it unless you know what you’re doing. 😭

🎀 OPTIONS 🎀

• -h, —help — prints help.
• -g spacing, —grid-spacing spacing — controls the spacing of the test-ray grid in millimeters.
• -l, —view-left — visualizes solid segments occurring only in the left object.
• -r, —view-right — visualizes solid segments occurring only in the right object.
• -b, —view-both — visualizes solid segments occurring in both the left and right objects.
• -G, —grazing — reports differences in grazing hits. By default, grazing-hit differences are reported only when nearby offset rays confirm a difference; this option disables that filter.
• -S, —structure — enables structure-diff mode. Instead of raytracing, gdiff compares tree structure, matrices, boolean operators, and leaf geometry while ignoring object names. This mode does not currently produce visual output.

🌈 EXAMPLES 🌈

Example 1. Compare two region trees and visualize only their differing volume.

mged> gdiff —grid-spacing 1.0 left.r right.r

Shoots a comparison grid across left.r and right.r and displays segments that appear only in one object or the other. Slay, differences visualized. 🔥

Example 2. Compare tree structure without raytracing.

mged> gdiff —structure left.r right.r

Checks whether the two trees differ in matrices, booleans, or leaf geometry without generating view output. Structure tea, no raytracing required. 🧚

👑 AUTHOR 👑

Clifford Yapp 👑

📜 COPYRIGHT 📜

This software is Copyright (c) 2016-2026 United States Government as represented by the U.S. Army Research Laboratory.

🐛 BUG REPORTS 🐛

Reports of bugs or problems should be submitted via electronic mail to devs@brlcad.org. Don’t be shy — they want the tea. 🫶

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💖 mwah, that’s the whole page — signing off from BRL-CAD with GDIFF(nged) energy. The date? Not listed on this page, bestie, so I’m not inventing one. Periodt. 🫶