DM_OGL_PROBE(1)

NAME

dm_ogl_probe - test whether a usable GLX/OpenGL display environment is available

On this page

SYNOPSIS
DESCRIPTION
OPTIONS
EXAMPLES
SEE ALSO
AUTHOR
COPYRIGHT
BUG REPORTS

SYNOPSIS

dm_ogl_probe [_display_]

dm_ogl_probe is a small helper utility used by BRL-CAD to determine, at run time, whether an X11 display supports a working GLX/OpenGL rendering context. It is the probe that backs the ogl display manager (the dm-ogl plugin): before BRL-CAD tools such as mged(1) or archer(1) attempt to open an ogl display, this probe can be run to confirm that the necessary GLX visual and context can actually be created.

The probe takes no flag options. It optionally accepts a single argument naming the X display to test; if omitted, the display named by the DISPLAY environment variable is used. dm_ogl_probe opens the display, verifies the GLX extension is present, searches for the deepest RGBA visual that supports OpenGL, creates an OpenGL context and a temporary window, and makes the context current. It then tears everything down and exits. No window is left on screen and nothing is printed on success; the result is communicated entirely through the exit status, making the tool suitable for use in scripts and build/setup logic.

The exit status indicates the outcome:

0 - a usable GLX/OpenGL context was created and made current.
2 - the display could not be opened.
3 - the X server does not provide the GLX extension.
4 - no suitable RGBA OpenGL visual was found.
5 - an OpenGL context could not be created.
6 - the temporary test window could not be created.
7 - the context could not be made current.

OPTIONS

display: The X display to probe, in standard X11 form (for example :0, :0.0, or hostname:0). When omitted, the DISPLAY environment variable selects the display.

EXAMPLES

Example 1. Probe the default display

dm_ogl_probe; echo $?

Tests the display named by DISPLAY and prints the exit status. A printed 0 means an ogl display manager can be opened on this display.

Example 2. Gate launching an OpenGL session on probe success

if dm_ogl_probe ":0"; then
    mged -c model.g
else
    echo "GLX/OpenGL not available on :0, falling back" >&2
fi

Runs the probe against display :0 and only launches mged(1) when a working GLX/OpenGL context is available, otherwise reporting the failure so a different display manager (such as X or swrast) can be selected.