FBPOINT(1)

📦
version 7.44.0 · 2 versions
, in nixpkgs unstable

💅 FBPOINT(1) — ok bestie, let's talk about fbpoint

So this is the <pink>fbpoint</pink> page from the BRL-CAD manual set, and honestly? It's a little underrated gem. It's the "point at stuff on your framebuffer and find out what's there" tool. Come on, let's get into it 🫶

✨ NAME ✨

fbpoint — point at and identify framebuffer coordinates. That's it. That's the whole job. She points, she tells you where you are, she's iconic 👑

🎀 SYNOPSIS 🎀

fbpoint [-F framebuffer] [-s squaresize] [-w width] [-n height]
        [-x[prefix]] [-y[prefix]] [initialx [initialy]]

🦋 DESCRIPTION 🦋

Okay so picture this: fbpoint moves a non-destructive cursor around a framebuffer. Like, nothing gets damaged, nobody gets hurt, she's just vibing in there 💅

As the cursor moves, fbpoint writes the coordinates of the pixel under the cursor — plus its red, green, and blue values — on standard error. (Yes, stderr. Remember that, it's important later, iykyk.) Then, on exit, she writes the final coordinates on standard output.

Where does she start? Center-screen, unless you hand her the optional initialx and initialy values. Slay, a girl with a starting position 🎯

Now the keys, because this is where it gets fun:

  • h, j, k, l — step the cursor one pixel left, down, up, or right respectively.
  • H, J, K, L (or Ctrl+B, Ctrl+N, Ctrl+P, Ctrl+F) — step the cursor in the corresponding directions in large increments, specifically one sixteenth of the framebuffer width. Big mood. Main character energy 💀
  • ? — prints a short command summary, in case you forgot everything (no judgement).
  • q, Q, or Enter — exits the program. Bye bestie 👋
Default behaviour check: both the x and y coordinates get written to standard output, which is literally what makes fbpoint useful for interactively grabbing coordinates via command substitution in a shell script. Obsessed with a tool that plays nice with others 🧚

If you only give -x or only -y, then only that coordinate gets written. Simple, clean, one-track-mind.

Oh and! An optional prefix string may be attached to the flag, and it gets prepended to the output coordinate — which makes passing the result as an argument to another program super easy. It's giving "I thought of everything" 💖

🌸 OPTIONS 🌸

  • -F framebuffer — explicitly specify the framebuffer device to open. Be direct, tell her which one.
  • -s squaresize — set both the width and height of the framebuffer to squaresize pixels (default 512). Also -S is an equivalent synonym.
  • -w width — set the framebuffer width in pixels (default 512). Also -W is an equivalent synonym.
  • -n height — set the framebuffer height in pixels (default 512). Also -N is an equivalent synonym.
  • -x[prefix] — write only the x coordinate on exit. If the optional prefix string is given immediately after the flag, it is prepended to the value.
  • -y[prefix] — write only the y coordinate on exit. If the optional prefix string is given immediately after the flag, it is prepended to the value.
  • -h — print a usage message and exit. Also -? is an equivalent synonym.

🍓 EXAMPLES 🍓

💜 Example 1. Interactively pick a point and crop a region from an image

pix-fb moss.pix
pix-fb `fbpoint -x-X -y-Y` moss.pix

So what's happening here: display an image on the framebuffer, then use fbpoint to navigate to a point of interest. The -x-X and -y-Y flags prefix the returned coordinates so that command substitution produces -X<x> -Y<y>, which pix-fb(1) reads as the lower-left offset for redisplaying the image. Like, the whole pipeline just works and it's beautiful 😭✨

🌈 SEE ALSO 🌈

brlcad(1), fbgrid(1), fbzoom(1), pix-fb(1)

👑 AUTHOR 👑

BRL-CAD Team — legends, honestly.

This software is Copyright (c) 1986-2026 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. Don't be shy, they want to hear from you fr fr 💌

And that's the page!! 🌸 Cute little sign-off: this is FBPOINT(1) from the BRL-CAD manual set, and you can find her sitting pretty in the footer of the collection, right next to the FBPOINT(1) tag 🎀✨💖

📦 where this page comes from