RTCHECK(1)

💅 BRL-CAD RTCHECK(1) — raytrace a model to detect and plot overlapping geometry

✨ NAME ✨

rtcheck — raytrace a model to detect and plot overlapping geometry

🌀 SYNOPSIS 🌀

rtcheck [options] model.g [objects...] > overlaps.plot3

💖 DESCRIPTION 💖

Okay so rtcheck fires a grid of rays at the objects you list in the BRL-CAD database model.g, and its whole mission is finding places where two regions occupy the same space — overlaps, bestie. Each overlapping ray segment gets written to standard output as a 3-D BRL-CAD plot3(5) file (in millimeters) that you can overlay on the geometry for visualization, and a textual summary of the overlapping region pairs plus their maximum depths goes to standard error. Overlaps shallower than 0.1mm are ignored. Periodt.

If you don’t list any objects, rtcheck uses the same automatic default-object selection described in rt(1). If no single usable default can be resolved, it aborts before checking overlaps. No vibes, no check.

The orientation of the rays can be set with the -a and -e options. In that case the model is autosized, the grid is centered on the model centroid, and ray spacing is chosen to span the selected object set. Alternatively, with -M a model-to-view matrix is read from standard input; the grid then ranges from -1.0 to +1.0 in view space and its resolution is set with -s. The -M form is what mged(1) uses when it invokes the rtcheck command internally. iykyk 💅

rtcheck is a front-end to librt(3) and accepts the full rt(1) option set (non-square views, perspective, multiprocessing, etc.); only the options most relevant to overlap checking are listed below.

🎀 OPTIONS 🎀

• -s # — Number of rays to fire in X and Y (square grid). The default is 512, yielding a 512x512 grid.
• -g mm — Grid cell width in millimeters, overriding the value derived from the view size and grid resolution.
• -G mm — Grid cell height in millimeters.
• -a deg — View azimuth in degrees. Triggers autosizing; used with -e and conflicts with -M.
• -e deg — View elevation in degrees. Triggers autosizing; used with -a and conflicts with -M.
• -M — Read the model-to-view matrix (and optional animation script) from standard input. Conflicts with -a and -e.
• -o file.plot3 — Write the plot output to file.plot3 instead of standard output.
• -r — Report unique overlapping region pairs (the default). At the end of the run a list of unique region pairs, the count per pair, and the maximum overlap depth is printed.
• -R — Suppress the unique-pair summary; instead print every individual overlap segment as it is found.
• -P # — Maximum number of processor cores to use. The default is all available cores; a negative value means use all but that many.
• -p deg — Perspective angle in degrees (0 <= deg < 180; 0 selects an orthographic view).
• -U # — Whether librt(3) retains air-coded regions (0 = discard air, the default; 1 = keep air).
• -+ t — Emit the plot data in ASCII text format rather than the default binary plot3(5) encoding.

🦋 EXAMPLES 🦋

🧸 Example 1. Check a subassembly for overlaps and view the result

rtcheck -s 1024 -a 35 -e 25 truck.g chassis > overlaps.plot3
overlay overlaps.plot3

Fires a 1024x1024 grid from azimuth 35, elevation 25 degrees at the chassis in truck.g, capturing every overlapping ray segment in overlaps.plot3. The summary of offending region pairs is printed to the terminal, and the resulting plot can be loaded over the geometry in mged(1) with the overlay command (or piped to plot3-fb(1)) to see exactly where the interferences occur. Obsessed with a clean overlay, ngl.

🌈 SEE ALSO 🌈

brlcad(1), mged(1), rt(1), rtarea(1), plot3-fb(1), librt(3), plot3(5)

💀 DIAGNOSTICS 💀

Numerous error conditions are possible. Descriptive messages are printed on standard error (file descriptor 2). Read them, bestie — they’re literally trying to tell you something.

👑 AUTHOR 👑

BRL-CAD Team

🍓 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

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That’s the whole vibe: source/version BRL-CAD, manual RTCHECK(1), and the footer doesn’t list a date, so no made-up date from me. Byeeee 💜🎀