G2ASC(1)

NAME

g2asc - convert a BRL-CAD geometry database from binary to ASCII

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SYNOPSIS
DESCRIPTION
DEPRECATION
OPTIONS
EXAMPLES
SEE ALSO
AUTHOR
COPYRIGHT
BUG REPORTS

SYNOPSIS

g2asc [-h] input.g output.asc

g2asc reads a binary BRL-CAD ".g" geometry database and writes an ASCII representation of it. It is the converse of asc2g(1); together the two programs form a pair of filters for moving geometry between the binary and ASCII forms.

The output format depends on the version of the input database. A modern "v5" database is exported as a Tcl command script (a sequence of put, attr, and similar commands). An older "v4" database is exported in the legacy one-line record format.

The "v5" binary format is already machine independent, so converting to ASCII is no longer required merely to transfer a database between differing computer architectures; g2asc remains useful for inspecting, editing, or diff’ing geometry as text.

Both an input and an output file name are required. Either may be given as a single dash (-) to use standard input or standard output, but a dash is rejected for "v5" databases: those must be named regular files. The input and output may not refer to the same file.

DEPRECATION

g2asc is not deprecated and remains a supported part of BRL-CAD. However, its original purpose — producing an architecture-independent ASCII form of a geometry database for transfer between machines — has been obsoleted by the machine-independent "v5" binary ".g" format, which can be moved between systems directly. For that reason, g2asc is no longer needed for portability. It is still applicable for inspecting, editing, or diff’ing geometry as text, after which asc2g(1) can convert the result back to binary form.

OPTIONS

-h, --help: Print a usage summary and exit. The hidden alias -? is also accepted.

EXAMPLES

Example 1. Round-trip a database through ASCII to edit it as text

g2asc model.g model.asc
sed -i 's/old_part/new_part/g' model.asc
asc2g model.asc model_edited.g

Export model.g to a text file, rename an object with a stream editor, then reimport the result with asc2g(1). This text round-trip is handy for bulk edits or scripted fixups that are awkward inside mged(1).

Example 2. Inspect what changed between two databases

g2asc before.g before.asc
g2asc after.g after.asc
diff before.asc after.asc

Convert two binary databases to ASCII and diff them to see exactly which objects and parameters differ, which is impossible directly on the binary form.