man/man1/robjutil.1

.\" RCSid "$Id: robjutil.1,v 1.6 2021/03/12 18:32:33 greg Exp $"
.TH ROBJUTIL 1 3/31/20 RADIANCE
.SH NAME
robjutil - operate on Wavefront .OBJ file
.SH SYNOPSIS
.B robjutil
[
.B +/-r
][
.B +/-v
][
.B +/-t
][
.B +/-n
][
.B "+/-m mname"
][
.B "+/-g gname"
][
.B "-c epsilon"
][
.B +T
][
.B "-x 'xf spec'"
]
[
.B input.obj ..
]
.SH DESCRIPTION
.I Robjutil
reads and manipulates a Wavefront .OBJ file, removing degenerate and
duplicate faces.
If the
.I +r
option is specified, a Radiance scene description
will be produced on the standard output.
If
.I -r
is given, a modified .OBJ file will be sent to the standard output.
This is the default, and is more useful for preserving
texture coordinates if directed to
.I obj2mesh(1).
.PP
The
.I +v
option turns on verbose progress reports.
.PP
The
.I \-t
option tells
.I robjutil
to remove texture coordinates from the input.
The
.I \-n
option will cause all surface normals to be removed.
.PP
The
.I "\-m mname"
option tells
.I robjutil
to remove all faces that use the material
.I mname.
Multiple
.I \-m
options may be given, each with a single (unique) material name.
Alternatively, the
.I "+m mname"
option may be used to specify a material one wishes to keep, discarding the rest.
Multiple
.I +m
options will keep all the named materials.
The
.I \-m
and
.I \+m
options are mutually exclusive.
.PP
Similarly, the
.I "\-g gname"
option says to remove all faces belonging to the group
.I gname,
and multiple
.I \-g
options may be given.
There is also a
.I +g
option to save just the named group(s).
Object statements are treated the same as group statements in the input, so
.I +/-g
option can also be applied to object names.
Note that an object name will be overridden by a group name that follows
it in the input, and vice versa.
.PP
The
.I "\-c epsilon"
option tells
.I robjutil
to coalesce vertices that are within the given epsilon.
This is useful to improve the connectivity of models that were produced
in a sloppy conversion process from independent polygons.
When producing a Radiance file via the
.I +r
option, there will be no savings in the output size, but there can be
a benefit in reducing the number of "cracks" in the resulting geometry,
at least for triangle mesh input.
.I Robjutil
does not attempt to break up non-planar polygons into triangles,
which is usually not a problem for .OBJ output, but may be for Radiance
scene descriptions (+r).
.PP
The
.I +T
option turns all faces with 4 or more sides into triangles.
.PP
The
.I \-x
option may be used to specify a final transform to apply to all
coordinates in the file before output.
This specification must be contained in a single quoted word and
match the standard arguments used by
.I xform(1),
except that the
.I \-a
option is not supported for creating arrays of objects.
Also, any scaling factors do not affect the epsilon value given for
coalescing vertices, as this operation is applied prior to the transform,
even if
.I \-c
appears later in the command line.
.SH EXAMPLES
To remove degenerate and duplicate faces from "orig.obj" and write to "final.rad":
.IP "" .2i
robjutil +r orig.obj > final.rad
.PP
To extract only the groups "cat" and "bell" from the file "kitty.obj" and
write to a Radiance triangle mesh using materials from "kitty.mat":
.IP "" .2i
robjutil +g cat +g bell kitty.obj | obj2mesh -a kitty.mat > kitty.rtm
.PP
To rotate the scene 90 degrees about the Y-axis and scale by 10:
.IP "" .2i
robjutil -x "-ry 90 -s 10" orig.obj > transformed.obj
.SH NOTES
The .OBJ output of
.I robjutil
uses relative indices, so files it produces may be concatenated
on the input of other tools such as
.I obj2rad
and
.I obj2mesh
by piping from
.I cat(1)
or similar.
This offers a convenient way to separate geometry from a single .OBJ
input, manipulate it in some way, then recombine during conversion.
.PP
Unlike
.I obj2rad
and
.I obj2mesh,
.I robjutil
with the
.I +r
option will not substitute the group name for a material id if no
.I usemtl
statements are found on the input.
Instead, it will assign each surface the material
.I DEFAULT_MATERIAL.
Since it is possible to use the
.I +/-g
option to select groups to include or exclude on output, it is
still possible to assign materials by group manually.
.SH AUTHOR
Greg Ward
.SH "SEE ALSO"
cat(1), genbox(1), gensurf(1), obj2mesh(1), obj2rad(1) oconv(1), xform(1)
Revision:	1.7
Committed:	Thu Apr 15 23:51:04 2021 UTC (4 years, 1 month ago) by greg
Branch:	MAIN
Changes since 1.6:	+5 -13 lines
Log Message:	feat(genbox,robjutil): Added Radiance normal smoothing support to wfobj library
#	Content
1	.\" RCSid "$Id: robjutil.1,v 1.6 2021/03/12 18:32:33 greg Exp $"
2	.TH ROBJUTIL 1 3/31/20 RADIANCE
3	.SH NAME
4	robjutil - operate on Wavefront .OBJ file
5	.SH SYNOPSIS
6	.B robjutil
7	[
8	.B +/-r
9	][
10	.B +/-v
11	][
12	.B +/-t
13	][
14	.B +/-n
15	][
16	.B "+/-m mname"
17	][
18	.B "+/-g gname"
19	][
20	.B "-c epsilon"
21	][
22	.B +T
23	][
24	.B "-x 'xf spec'"
25	]
26	[
27	.B input.obj ..
28	]
29	.SH DESCRIPTION
30	.I Robjutil
31	reads and manipulates a Wavefront .OBJ file, removing degenerate and
32	duplicate faces.
33	If the
34	.I +r
35	option is specified, a Radiance scene description
36	will be produced on the standard output.
37	If
38	.I -r
39	is given, a modified .OBJ file will be sent to the standard output.
40	This is the default, and is more useful for preserving
41	texture coordinates if directed to
42	.I obj2mesh(1).
43	.PP
44	The
45	.I +v
46	option turns on verbose progress reports.
47	.PP
48	The
49	.I \-t
50	option tells
51	.I robjutil
52	to remove texture coordinates from the input.
53	The
54	.I \-n
55	option will cause all surface normals to be removed.
56	.PP
57	The
58	.I "\-m mname"
59	option tells
60	.I robjutil
61	to remove all faces that use the material
62	.I mname.
63	Multiple
64	.I \-m
65	options may be given, each with a single (unique) material name.
66	Alternatively, the
67	.I "+m mname"
68	option may be used to specify a material one wishes to keep, discarding the rest.
69	Multiple
70	.I +m
71	options will keep all the named materials.
72	The
73	.I \-m
74	and
75	.I \+m
76	options are mutually exclusive.
77	.PP
78	Similarly, the
79	.I "\-g gname"
80	option says to remove all faces belonging to the group
81	.I gname,
82	and multiple
83	.I \-g
84	options may be given.
85	There is also a
86	.I +g
87	option to save just the named group(s).
88	Object statements are treated the same as group statements in the input, so
89	.I +/-g
90	option can also be applied to object names.
91	Note that an object name will be overridden by a group name that follows
92	it in the input, and vice versa.
93	.PP
94	The
95	.I "\-c epsilon"
96	option tells
97	.I robjutil
98	to coalesce vertices that are within the given epsilon.
99	This is useful to improve the connectivity of models that were produced
100	in a sloppy conversion process from independent polygons.
101	When producing a Radiance file via the
102	.I +r
103	option, there will be no savings in the output size, but there can be
104	a benefit in reducing the number of "cracks" in the resulting geometry,
105	at least for triangle mesh input.
106	.I Robjutil
107	does not attempt to break up non-planar polygons into triangles,
108	which is usually not a problem for .OBJ output, but may be for Radiance
109	scene descriptions (+r).
110	.PP
111	The
112	.I +T
113	option turns all faces with 4 or more sides into triangles.
114	.PP
115	The
116	.I \-x
117	option may be used to specify a final transform to apply to all
118	coordinates in the file before output.
119	This specification must be contained in a single quoted word and
120	match the standard arguments used by
121	.I xform(1),
122	except that the
123	.I \-a
124	option is not supported for creating arrays of objects.
125	Also, any scaling factors do not affect the epsilon value given for
126	coalescing vertices, as this operation is applied prior to the transform,
127	even if
128	.I \-c
129	appears later in the command line.
130	.SH EXAMPLES
131	To remove degenerate and duplicate faces from "orig.obj" and write to "final.rad":
132	.IP "" .2i
133	robjutil +r orig.obj > final.rad
134	.PP
135	To extract only the groups "cat" and "bell" from the file "kitty.obj" and
136	write to a Radiance triangle mesh using materials from "kitty.mat":
137	.IP "" .2i
138	robjutil +g cat +g bell kitty.obj \| obj2mesh -a kitty.mat > kitty.rtm
139	.PP
140	To rotate the scene 90 degrees about the Y-axis and scale by 10:
141	.IP "" .2i
142	robjutil -x "-ry 90 -s 10" orig.obj > transformed.obj
143	.SH NOTES
144	The .OBJ output of
145	.I robjutil
146	uses relative indices, so files it produces may be concatenated
147	on the input of other tools such as
148	.I obj2rad
149	and
150	.I obj2mesh
151	by piping from
152	.I cat(1)
153	or similar.
154	This offers a convenient way to separate geometry from a single .OBJ
155	input, manipulate it in some way, then recombine during conversion.
156	.PP
157	Unlike
158	.I obj2rad
159	and
160	.I obj2mesh,
161	.I robjutil
162	with the
163	.I +r
164	option will not substitute the group name for a material id if no
165	.I usemtl
166	statements are found on the input.
167	Instead, it will assign each surface the material
168	.I DEFAULT_MATERIAL.
169	Since it is possible to use the
170	.I +/-g
171	option to select groups to include or exclude on output, it is
172	still possible to assign materials by group manually.
173	.SH AUTHOR
174	Greg Ward
175	.SH "SEE ALSO"
176	cat(1), genbox(1), gensurf(1), obj2mesh(1), obj2rad(1) oconv(1), xform(1)