patch-g — convert FASTGEN ASCII databases into binary MGED databases.


patch-g [options] output.g


This program converts FASTGEN geometry into BRL-CAD mged(1) formats. FASTGEN is a modeling system used by the Air Force and Navy to create military target descriptions. FASTGEN databases consist of the following primitives which can be converted by patch-g : polygons, plates, boxes, wedges, cylinders, spheres, and rods. It is recommended that patch-g be run with the -p option for most uses.

patch-g requires that the FASTGEN file be run through the pre-processor rpatch . This is achieved by executing rpatch<fastgen_file>file.rpatch. Once this step is executed, patch-g can be used to convert the intermediate file into a binary brlcad(1) ".g" file.

patch-g will provide messages when encountering problems in the conversion of FASTGEN geometry. For further debugging information, the -d flag with levels 1-3 of debugging can be provided.

The available options are:

-T tolerance_distance

The tolerance_distance is specified in inches. Any two vertices within this distance from each other will be considered the same vertex.

-A perp_tolerance

The perp_tolerance is specified as the cosine of an angle (0.0 through 1.0). If the cosine of the angle between two vectors is less than the specified tolerance, then the vectors are considered perpendicular.

-u number_of_unions

The number_of_unions is the number of union operations per region, and has a pre-specified default value.

-x librt_debug_flag

Specifies a flag for debugging the librt package.

-X NMG_debug_flag

Specifies a flag for NMG routine debugging.


Produce polysolid output rather than the default NMG solids.


Convert plate-mode triangles using ARB6 solids.

-f preprocessed_input_file

Use the specified file as the input for conversion.

-i labels_file

Specifies desired group names to override defaults.

-m materials_file

Specifies material properties to be assigned to components.


Process volume mode as plate mode.

-t title

Specifies a title for the output model (default is "patch-g conversion").

-o top_level_name

Specifies a name for the top level object (default is "all").


Reverse normals for plate mode triangles.

-c "X Y Z"

Specifies centroid, in inches, for some plate mode surface normal calculations. Quotation marks are needed to provide for the embedded blanks.

-d debug_level

Specifies a debug level (1-3).


rpatch < fastgen_file > file.rpatch

patch-g -p -f file.rpatch file.g


The diagnostics are intended to be self-explanatory.


brlcad(1), mged(1)


Bill Mermagen, Jr.


This software is Copyright (c) 1991-2016 by the United States Government as represented by U.S. Army Research Laboratory.


Reports of bugs or problems should be submitted via electronic mail to <>.