man/man1/tmesh2rad.1

.\" RCSid "$Id"
.TH TMESH2RAD 1 3/18/96 RADIANCE
.SH NAME
tmesh2rad - convert a triangular mesh to a RADIANCE scene description
.SH SYNOPSIS
.B tmesh2rad
[
.B "\-o obj"
][
.B "\-m mat"
][
.B "\-p pat"
]
[
.B input ..
]
.SH DESCRIPTION
.I Tmesh2rad
converts one or more triangle-mesh files to a RADIANCE scene description.
The
.I \-o
option may be used to assign a default object name.
The single letter "T" is used if no name is given on the command
line or in the file.
The
.I \-m
option may be used to assign a default material name.
The non-material "void" is used as a default if none is given on the
command line or in the file.
The
.I \-p
option may be used to assign a default picture for a surface
pattern.
If none is given on the command line or in the file, the surface
will not have an associated pattern.
.SH "FILE FORMAT"
A triangle-mesh is a free-format ASCII file
composed of the following eight primitive
types.
Each primitive is begun with a single, white-space-delimited letter:
.TP 10n
.BI # \ Comment
Whatever follows up until the end of line is passed as a comment
to the output.
Note that there must be at least one space or tab
following the pound-sign.
.TP
.BI o \ name
The white-space-delimited string
.I name
is used as a prefix for all following output triangles.
.TP
.BI m \ material
The white-space-delimited string
.I material
is used as the modifier name for all following output triangles.
.TP
.BI p \ picture
The white-space-delimited string
.I picture
is used as the name of the RADIANCE picture file
to be used as a pattern for
all following output triangles with properly defined vertices.
(See
.I i
primitive below.)\0
.TP
.BI v " id x y z"
Defines the vertex
.I id
with 3-dimensional coordinates
.I "x, y"
and
.I z.
The identifier,
.I id
must be some small, non-negative integer value.
If the same integer is used for a later vertex definition,
this definition will be lost, though any triangles using the
vertex prior to its redefinition will be unaffected.
.TP
.BI n " nx ny nz"
Defines a surface normal vector with the 3-dimensional components
.I "nx, ny"
and
.I nz.
This vector will be associated with the most recently defined
vertex, and is often placed on the same line as the vertex
definition for clarity.
The vector need not be normalized.
.TP
.BI i " u v"
Defines a picture index for the most recently defined vertex.
The
.I u
value will be used to lookup the horizontal pixel coordinate
in the currently defined picture.
The
.I v
value will be used to lookup the vertical pixel coordinate.
(See the RADIANCE reference manual for details on picture coordinate
values.)\0
As with associated surface normals, picture indices are interpolated
using barycentric coordinates based on the triangle vertices.
If these coordinates are calculated correctly, this
should result in a smooth mapping of a pattern onto the
surface mesh.
.TP
.BI t " id1 id2 id3"
Create a triangle connecting the three vertices identified by
.I "id1, id2"
and
.I id3.
The right-hand rule is used to determine the default surface
normal orientation, and this should not be too far from the
associated vertex normals (if any).
All three vertices must have an associated normal if the triangle
is to be smoothed.
If a picture file is defined and all three vertices have pattern
indices associated with them, then this picture will be used as a
pattern to modify the triangle's color.
.PP
We realize there are many similar
T-mesh file formats in existence, and that it would have been just
as easy to support one of these formats directly.
The disadvantage to supporting an existing format is that conversion
from other formats might prove difficult.
It was our hope to provide a "greatest common multiple" format that
would support all similar T-mesh formats, rather than supporting
WaveFront's .obj format (for example) and being unable to associate
a pattern with an object.
Converting from other formats should be relatively straightforward.
In many cases, an
.I "awk(1), rcalc(1)"
or even a
.I sed(1)
script should be sufficient.
.SH EXAMPLE
Here is an example T-mesh file:
.sp
.RS
.nf
# Our object name:
o test_object
# Our material:
m puce
# Our vertices:
v 1     10      15      5
v 2     10      -15     5
v 3     0       -15     0
v 4     -10     15      -5
# Two triangles joined together:
t 1 2 3
t 2 3 4
.fi
.RE
.sp
Which generates the following output:
.sp
.RS
.nf
## T-mesh read from: <stdin>

# Our material:

# Our vertices:

# Two triangles joined together:

puce polygon test_object.1
0
0
9
                10                 15                  5
                10                -15                  5
                 0                -15                  0

puce polygon test_object.2
0
0
9
                10                -15                  5
                 0                -15                  0
               -10                 15                 -5
.fi
.RE
.sp
.PP
Here is another example:
.sp
.RS
.nf
# A partial cylinder:
m BluePlastic
v 1 -14.673 -3.119    50 n -0.95677 -0.203374 1.17936e-10
v 2 -12.136 -8.817   -50 n -0.791363 -0.574922 4.84915e-10
v 3 -12.136 -8.817    50 n -0.791363 -0.574922 4.84915e-10
t 1 2 3
m OrangePlastic
v 1 -7.501 -12.991    50 n -0.549094 -0.812427 -1.45812e-09
v 2 -12.136 -8.817    50 n -0.791363 -0.574922 4.84915e-10
v 3 -12.136 -8.817   -50 n -0.791363 -0.574922 4.84915e-10
t 1 2 3
m BluePlastic
v 1 -1.568 -14.918    50 n -0.171094 -0.965568 -5.69788e-09
v 2 -7.501 -12.991    50 n -0.549094 -0.812427 -1.45812e-09
v 3 -7.501 -12.991   -50 n -0.429001 -0.881759 -3.6502e-09
t 1 2 3
.fi
.RE
.sp
Note that the same three vertices were used repeatedly, and
intermingled with the triangle definitions.
.SH AUTHOR
Greg Ward
.SH BUGS
Triangle smoothing doesn't work very well for glass or trans
material types in Radiance, since textures cause distorted
transmission through these materials.
It is best to use the dielectric material type if smooth
transmission is desired.
.SH "SEE ALSO"
arch2rad(1), awk(1), ies2rad(1), thf2rad(1),
oconv(1), rcalc(1), sed(1), xform(1)
Revision:	1.1
Committed:	Tue Mar 11 19:20:21 2003 UTC (21 years, 2 months ago) by greg
Branch:	MAIN
CVS Tags:	rad3R5
Log Message:	Added documentation to repository
#	User	Rev	Content
1	greg	1.1	.\" RCSid "$Id"
2			.TH TMESH2RAD 1 3/18/96 RADIANCE
3			.SH NAME
4			tmesh2rad - convert a triangular mesh to a RADIANCE scene description
5			.SH SYNOPSIS
6			.B tmesh2rad
7			[
8			.B "\-o obj"
9			][
10			.B "\-m mat"
11			][
12			.B "\-p pat"
13			]
14			[
15			.B input ..
16			]
17			.SH DESCRIPTION
18			.I Tmesh2rad
19			converts one or more triangle-mesh files to a RADIANCE scene description.
20			The
21			.I \-o
22			option may be used to assign a default object name.
23			The single letter "T" is used if no name is given on the command
24			line or in the file.
25			The
26			.I \-m
27			option may be used to assign a default material name.
28			The non-material "void" is used as a default if none is given on the
29			command line or in the file.
30			The
31			.I \-p
32			option may be used to assign a default picture for a surface
33			pattern.
34			If none is given on the command line or in the file, the surface
35			will not have an associated pattern.
36			.SH "FILE FORMAT"
37			A triangle-mesh is a free-format ASCII file
38			composed of the following eight primitive
39			types.
40			Each primitive is begun with a single, white-space-delimited letter:
41			.TP 10n
42			.BI # \ Comment
43			Whatever follows up until the end of line is passed as a comment
44			to the output.
45			Note that there must be at least one space or tab
46			following the pound-sign.
47			.TP
48			.BI o \ name
49			The white-space-delimited string
50			.I name
51			is used as a prefix for all following output triangles.
52			.TP
53			.BI m \ material
54			The white-space-delimited string
55			.I material
56			is used as the modifier name for all following output triangles.
57			.TP
58			.BI p \ picture
59			The white-space-delimited string
60			.I picture
61			is used as the name of the RADIANCE picture file
62			to be used as a pattern for
63			all following output triangles with properly defined vertices.
64			(See
65			.I i
66			primitive below.)\0
67			.TP
68			.BI v " id x y z"
69			Defines the vertex
70			.I id
71			with 3-dimensional coordinates
72			.I "x, y"
73			and
74			.I z.
75			The identifier,
76			.I id
77			must be some small, non-negative integer value.
78			If the same integer is used for a later vertex definition,
79			this definition will be lost, though any triangles using the
80			vertex prior to its redefinition will be unaffected.
81			.TP
82			.BI n " nx ny nz"
83			Defines a surface normal vector with the 3-dimensional components
84			.I "nx, ny"
85			and
86			.I nz.
87			This vector will be associated with the most recently defined
88			vertex, and is often placed on the same line as the vertex
89			definition for clarity.
90			The vector need not be normalized.
91			.TP
92			.BI i " u v"
93			Defines a picture index for the most recently defined vertex.
94			The
95			.I u
96			value will be used to lookup the horizontal pixel coordinate
97			in the currently defined picture.
98			The
99			.I v
100			value will be used to lookup the vertical pixel coordinate.
101			(See the RADIANCE reference manual for details on picture coordinate
102			values.)\0
103			As with associated surface normals, picture indices are interpolated
104			using barycentric coordinates based on the triangle vertices.
105			If these coordinates are calculated correctly, this
106			should result in a smooth mapping of a pattern onto the
107			surface mesh.
108			.TP
109			.BI t " id1 id2 id3"
110			Create a triangle connecting the three vertices identified by
111			.I "id1, id2"
112			and
113			.I id3.
114			The right-hand rule is used to determine the default surface
115			normal orientation, and this should not be too far from the
116			associated vertex normals (if any).
117			All three vertices must have an associated normal if the triangle
118			is to be smoothed.
119			If a picture file is defined and all three vertices have pattern
120			indices associated with them, then this picture will be used as a
121			pattern to modify the triangle's color.
122			.PP
123			We realize there are many similar
124			T-mesh file formats in existence, and that it would have been just
125			as easy to support one of these formats directly.
126			The disadvantage to supporting an existing format is that conversion
127			from other formats might prove difficult.
128			It was our hope to provide a "greatest common multiple" format that
129			would support all similar T-mesh formats, rather than supporting
130			WaveFront's .obj format (for example) and being unable to associate
131			a pattern with an object.
132			Converting from other formats should be relatively straightforward.
133			In many cases, an
134			.I "awk(1), rcalc(1)"
135			or even a
136			.I sed(1)
137			script should be sufficient.
138			.SH EXAMPLE
139			Here is an example T-mesh file:
140			.sp
141			.RS
142			.nf
143			# Our object name:
144			o test_object
145			# Our material:
146			m puce
147			# Our vertices:
148			v 1 10 15 5
149			v 2 10 -15 5
150			v 3 0 -15 0
151			v 4 -10 15 -5
152			# Two triangles joined together:
153			t 1 2 3
154			t 2 3 4
155			.fi
156			.RE
157			.sp
158			Which generates the following output:
159			.sp
160			.RS
161			.nf
162			## T-mesh read from: <stdin>
163
164			# Our material:
165
166			# Our vertices:
167
168			# Two triangles joined together:
169
170			puce polygon test_object.1
171			0
172			0
173			9
174			10 15 5
175			10 -15 5
176			0 -15 0
177
178			puce polygon test_object.2
179			0
180			0
181			9
182			10 -15 5
183			0 -15 0
184			-10 15 -5
185			.fi
186			.RE
187			.sp
188			.PP
189			Here is another example:
190			.sp
191			.RS
192			.nf
193			# A partial cylinder:
194			m BluePlastic
195			v 1 -14.673 -3.119 50 n -0.95677 -0.203374 1.17936e-10
196			v 2 -12.136 -8.817 -50 n -0.791363 -0.574922 4.84915e-10
197			v 3 -12.136 -8.817 50 n -0.791363 -0.574922 4.84915e-10
198			t 1 2 3
199			m OrangePlastic
200			v 1 -7.501 -12.991 50 n -0.549094 -0.812427 -1.45812e-09
201			v 2 -12.136 -8.817 50 n -0.791363 -0.574922 4.84915e-10
202			v 3 -12.136 -8.817 -50 n -0.791363 -0.574922 4.84915e-10
203			t 1 2 3
204			m BluePlastic
205			v 1 -1.568 -14.918 50 n -0.171094 -0.965568 -5.69788e-09
206			v 2 -7.501 -12.991 50 n -0.549094 -0.812427 -1.45812e-09
207			v 3 -7.501 -12.991 -50 n -0.429001 -0.881759 -3.6502e-09
208			t 1 2 3
209			.fi
210			.RE
211			.sp
212			Note that the same three vertices were used repeatedly, and
213			intermingled with the triangle definitions.
214			.SH AUTHOR
215			Greg Ward
216			.SH BUGS
217			Triangle smoothing doesn't work very well for glass or trans
218			material types in Radiance, since textures cause distorted
219			transmission through these materials.
220			It is best to use the dielectric material type if smooth
221			transmission is desired.
222			.SH "SEE ALSO"
223			arch2rad(1), awk(1), ies2rad(1), thf2rad(1),
224			oconv(1), rcalc(1), sed(1), xform(1)