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.\" RCSid "$Id: obj2rad.1,v 1.4 2007/09/04 17:36:40 greg Exp $"
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.TH ROBJUTIL 1 3/31/20 RADIANCE
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.SH NAME
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robjutil - operate on Wavefront .OBJ file
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.SH SYNOPSIS
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.B robjutil
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[
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.B +/-r
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][
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.B +/-v
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][
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.B +/-t
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][
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.B +/-n
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][
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.B "+/-m mname"
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][
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.B "+/-g gname"
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][
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.B "-c epsilon"
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]
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[
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.B input.obj ..
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]
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.SH DESCRIPTION
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.I Robjutil
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reads and manipulates a Wavefront .OBJ file, removing degenerate and
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duplicate faces.
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If the
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.I +r
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option is specified, a Radiance scene description
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will be produced on the standard output.
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If
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.I -r
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is given, a modified .OBJ file will be sent to the standard output.
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This is the default, and is
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typically more useful, since surface normals are better handled by the
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.I obj2rad(1)
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and
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.I obj2mesh(1)
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converters.
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The latter also preserves local texture coordinates for mapping materials.
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The
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.I +v
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option turns on verbose progress reports.
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.PP
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The
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.I \-t
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option tells
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.I robjutil
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to remove texture coordinates from the input.
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The
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.I \-n
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option will cause all surface normals to be removed.
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.PP
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The
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.I "\-m mname"
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option tells
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.I robjutil
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to remove all faces that use the material
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.I mname.
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Multiple
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.I \-m
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options may be given, each with a single (unique) material name.
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Alternatively, the
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.I "+m mname"
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option may be used to specify a material one wishes to keep, discarding the rest.
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Multiple
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.I +m
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options will keep all the named materials.
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The
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.I \-m
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and
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.I \+m
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options are mutually exclusive.
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Similarly, the
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.I "\-g gname"
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option says to remove all faces belonging to the group
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.I gname,
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and multiple
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.I \-g
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options may be given.
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There is also a
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.I +g
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option to save just the named group(s).
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.PP
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Finally, a
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.I "\-c epsilon"
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parameter may be given to coalesce vertices that are within the given epsilon.
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This is useful to improve the connectivity of models that were produced
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in a sloppy conversion process from independent polygons.
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When producing a Radiance file via the
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.I +r
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option, there will be no savings in the output size, but there can be
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a benefit in reducing the number of "cracks" in the resulting geometry,
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at least for triangle mesh input.
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.I Robjutil
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does not attempt to break up non-planar polygons into triangles,
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which is usually not a problem for .OBJ output, but may be for Radiance
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scene descriptions (+r).
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.SH EXAMPLES
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To remove degenerate and duplicate faces from "orig.obj" and write to "final.rad":
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.IP "" .2i
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robjutil +r orig.obj > final.rad
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.PP
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To convert the same file, preserving surface normal interpolation:
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.IP "" .2i
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robjutil orig.obj | obj2rad > withnormals.rad
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.PP
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To extract only the groups "cat" and "bell" from the file "kitty.obj" and
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write to a Radiance triangle mesh using materials from "kitty.mat":
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.IP "" .2i
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robjutil +g cat +g bell kitty.obj | obj2mesh -a kitty.mat > kitty.rtm
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.SH AUTHOR
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Greg Ward
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.SH "SEE ALSO"
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obj2mesh(1), obj2rad(1) oconv(1), xform(1)
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