FBLINE(1)

NAME

fbline - draw a colored line on a framebuffer

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SYNOPSIS
DESCRIPTION
OPTIONS
EXAMPLES
SEE ALSO
AUTHOR
COPYRIGHT
BUG REPORTS

SYNOPSIS

fbline [-c] [-F framebuffer] [-s squaresize] [-w width] [-n height]
       [-r red] [-g green] [-b blue] x1 y1 x2 y2

fbline draws a single line on the currently selected framebuffer between the points (x1, y1) and (x2, y2) using a Bresenham line algorithm. Endpoints that fall outside the framebuffer are clamped to the screen edges. Coordinates are given in framebuffer pixels with the origin at the lower-left corner.

The environment variable FB_FILE specifies the framebuffer to use; see brlcad(1). The framebuffer may instead be named explicitly with the -F option. By default the requested framebuffer size is 512x512 pixels and the line color is white (255, 255, 255).

Use fbpoint(1) to interactively determine endpoint coordinates.

OPTIONS

-c: Clear the framebuffer before drawing. By default the line is drawn over the existing image.
-F framebuffer: Explicitly specify the framebuffer device.
-s squaresize: Set both the width and height of the framebuffer to squaresize pixels. Also available as -S.
-w width: Set the framebuffer width in pixels. Also available as -W.
-n height: Set the framebuffer height in pixels. Also available as -N.
-r red: Red component [0..255] of the line color (default 255).
-g green: Green component [0..255] of the line color (default 255).
-b blue: Blue component [0..255] of the line color (default 255).
-h: Print a usage message and exit. Also available as -?.

EXAMPLES

Example 1. Draw crosshairs over an image on the framebuffer

pix-fb -s 512 image.pix
fbline -r 255 -g 0 -b 0 256 0 256 511
fbline -r 255 -g 0 -b 0 0 256 511 256

Display a 512x512 image with pix-fb(1), then overlay a red vertical and a red horizontal line through the center to mark the image center. Because fbline draws over the existing image without clearing it, successive invocations accumulate on the same framebuffer.