Provided by: radiance_4R1+20120125-1.1_amd64 
NAME
tmesh2rad - convert a triangular mesh to a RADIANCE scene description
SYNOPSIS
tmesh2rad [ -o obj ][ -m mat ][ -p pat ] [ input .. ]
DESCRIPTION
Tmesh2rad converts one or more triangle-mesh files to a RADIANCE scene description. The -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 -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 -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.
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:
# 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.
o name The white-space-delimited string name is used as a prefix for all following output triangles.
m material
The white-space-delimited string material is used as the modifier name for all following output
triangles.
p picture The white-space-delimited string 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
primitive below.)
v id x y z
Defines the vertex id with 3-dimensional coordinates x, y and z. The identifier, 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.
n nx ny nz
Defines a surface normal vector with the 3-dimensional components nx, ny and 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.
i u v Defines a picture index for the most recently defined vertex. The u value will be used to
lookup the horizontal pixel coordinate in the currently defined picture. The v value will be
used to lookup the vertical pixel coordinate. (See the RADIANCE reference manual for details
on picture coordinate values.) 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.
t id1 id2 id3
Create a triangle connecting the three vertices identified by id1, id2 and 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.
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 awk(1), rcalc(1) or even a sed(1) script
should be sufficient.
EXAMPLE
Here is an example T-mesh file:
# 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
Which generates the following output:
## 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
Here is another example:
# 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
Note that the same three vertices were used repeatedly, and intermingled with the triangle definitions.
AUTHOR
Greg Ward
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.
SEE ALSO
arch2rad(1), awk(1), ies2rad(1), thf2rad(1), oconv(1), rcalc(1), sed(1), xform(1)
RADIANCE 3/18/96 TMESH2RAD(1)