TMESH2RAD(1)						      General Commands Manual						      TMESH2RAD(1)

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 follow-
		 ing 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 nor-
		 malized.

       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 ver-
		 tices 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 for-
       mats 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  straight-
       forward.  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)