G-VRML(1)

NAME

g-vrml - convert a BRL-CAD geometry database to a VRML 2.0 file

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SYNOPSIS
DESCRIPTION
OPTIONS
EXAMPLES
SEE ALSO
AUTHOR
COPYRIGHT
BUG REPORTS

SYNOPSIS

g-vrml [-b | -e] [-v] [-d _calc_dist_tol_] [-a _abs_tess_tol_] [-r _rel_tess_tol_] [-n _norm_tess_tol_] [-u _units_] [-x _librt_debug_flag_] [-X _NMG_debug_flag_] [-o _output.wrl_] _database.g_ _object_ [_object_ ...]

g-vrml converts the named objects from a BRL-CAD geometry database (database.g) into a faceted Virtual Reality Modeling Language (VRML) version 2.0 file. By default each region is tessellated and its Boolean operations are evaluated through the NMG routines, producing a triangulated IndexedFaceSet per region. Region colors and shaders (plastic, glass, texture) are translated into VRML material and texture nodes, and regions using the light shader are emitted as VRML light sources.

The result is written to the file named with -o, or to standard output if -o is not given. Output units default to millimeters; see -u to select a different unit. The conversion is the inverse direction of importers such as vrml-g would be, and complements other geometry exporters such as g-stl(1) and g-obj(1).

OPTIONS

-b: Dump BOT (Bag of Triangles) primitives directly to the VRML file without performing any Boolean evaluation; non-BOT (CSG) primitives are skipped. Mutually exclusive with -e.
-e: Evaluate all geometry, tessellating and performing the Boolean evaluation of both CSG and BOT primitives. Mutually exclusive with -b.
-v: Verbose output; report conversion progress on standard error.
-d calc_dist_tol: Calculational distance tolerance in millimeters, used to distinguish neighboring vertices. The default is 0.005.
-a abs_tess_tol: Absolute tessellation tolerance in millimeters (maximum chord error). Setting this disables the relative tolerance.
-r rel_tess_tol: Relative tessellation tolerance, expressed as a fraction of the bounding box of each primitive. The default is 0.01.
-n norm_tess_tol: Surface normal tessellation tolerance in degrees (maximum allowed angle between approximated and true surface normals). Setting this disables the relative tolerance.
-u units: Units for the resulting VRML file. The default is mm. Any unit name accepted by BRL-CAD (for example m, cm, in, ft) may be used.
-x librt_debug_flag: Set the librt debug flag (hexadecimal). See raytrace.h for bit values.
-X NMG_debug_flag: Set the NMG debug flag (hexadecimal). See nmg.h for bit values.
-o output.wrl: Write output to the named file. If omitted, output is written to standard output.
-h, -?: Print a usage message and exit.

EXAMPLES

Example 1. Convert specific tops objects to a VRML file

g-vrml -o havoc.wrl -u m havoc.g havoc

Tessellates and Boolean-evaluates the havoc object from havoc.g and writes a VRML 2.0 model in meters to havoc.wrl, ready to load in a web or desktop VRML viewer.

Example 2. Export only the triangle meshes from a model

g-vrml -b -o meshes.wrl model.g body wheels

Dumps the BOT meshes contained under the body and wheels objects directly, skipping CSG primitives and the comparatively slow Boolean evaluation. This is useful when a model is already mostly faceted and you want a fast export.