fbpoint [-F framebuffer] [-s squaresize] [-w width] [-n height]
[-x[prefix]] [-y[prefix]] [initialx [initialy]]FBPOINT(1)
NAME
fbpoint - point at and identify framebuffer coordinates
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SYNOPSIS
DESCRIPTION
fbpoint moves a non-destructive cursor around a framebuffer. As the cursor moves, fbpoint writes the coordinates of the pixel under the cursor, along with its red, green, and blue values, on standard error. On exit, it writes the final coordinates on standard output.
The starting position is center-screen unless the optional initialx and initialy values are given.
The h, j, k, and l keys step the cursor one pixel left, down, up, or right respectively. The H, J, K, and L keys (or ^B, ^N, ^P, ^F) step the cursor in the corresponding directions in large increments (one sixteenth of the framebuffer width). A ? prints a short command summary, and q, Q, or Enter exits the program.
By default both the x and y coordinates are written to standard output, which makes fbpoint useful for interactively grabbing coordinates via command substitution in a shell script. If only -x or -y is given, only that coordinate is written. An optional prefix string may be attached to the flag and is prepended to the output coordinate to ease passing the result as an argument to another program.
OPTIONS
- -F framebuffer
-
Explicitly specify the framebuffer device to open.
- -s squaresize
-
Set both the width and height of the framebuffer to squaresize pixels (default 512). -S is an equivalent synonym.
- -w width
-
Set the framebuffer width in pixels (default 512). -W is an equivalent synonym.
- -n height
-
Set the framebuffer height in pixels (default 512). -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. -? 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.pixDisplay 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.
SEE ALSO
brlcad(1), fbgrid(1), fbzoom(1), pix-fb(1)
AUTHOR
BRL-CAD Team
COPYRIGHT
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