NAME

       xform - transform a RADIANCE scene description

SYNOPSIS

       xform [ -c ][ -I ][ -n name ][ -m newmod ][ -f argfile ][ xf0 ][ -a n1 xf1 ..  ][ -i 1 xff
       ] file ..

DESCRIPTION

       Xform transforms each scene description file according to the options given.  If  no  file
       is  specified, the standard input is read.  The -c option causes commands in the input not
       to be expanded.  The default is to execute all in line commands.  (See  note  below  about
       file  names.)   The  -n  option  causes  all identifiers to be prefixed with name.  The -m
       option causes all surfaces to be given the modifier newmod.   The  -I  option  causes  all
       surfaces  to  be inverted, reversing their surface normal orientations.  These options are
       followed by the transformation options, which are described below.

       The -f option causes the xform command line to be constructed  from  the  given  file,  by
       inserting  each  line of the file at the current point in the command argument list.  Each
       line in the file will result in a logically separate invocation  of  xform,  and  may  may
       contain  any valid xform arguments, including nested -f options.  This is a convenient way
       to specify multiple copies of an object that do not fit a regular array  pattern,  without
       having  to  actually execute xform many times.  Separate scene files may be specified this
       way as well, but remember that the constructed command line must fit the format of initial
       options  (-n,  -m,  -c,  -I)  followed  by the transform then the scene files.  No initial
       options may appear after the first transform option, and  no  transform  options  will  be
       understood  after  the first named file.  In the special case where the argument to the -f
       option is a hyphen ('-'), xform will take its arguments from  the  standard  input.   Note
       that xform cannot simultaneously take its scene information from the standard input if the
       option is used in this way.  Competely empty lines and lines beginning with a  pound  sign
       ('#')  will be silently ignored.  Beginning "!xform" or "xform" command names will also be
       ignored.

       If one or more scene files are given on the command line, xform will search  the  RADIANCE
       library  directories  for  each file.  (No search takes place if a file name begins with a
       '.', '/' or '~' character.)  Unless the -c option is present, xform will  also  change  to
       that  file's  directory  before  loading it.  Thus, any commands executed within that file
       will happen in that file's directory, which simplifies object hierarchy construction.

       The transformation consists of a sequence of operations which are executed  in  the  order
       they appear.

OPTIONS

       -t x y z  Translate the scene along the vector x y z .

       -rx degrees
                 Rotate  the  scene degrees about the x axis.  A positive rotation corresponds to
                 counter-clockwise when looking down the axis.

       -ry degrees
                 Rotate the scene degrees about the y axis.

       -rz degrees
                 Rotate the scene degrees about the z axis.

       -s factor Scale the scene by factor.

       -mx       Mirror the scene about the yz plane.

       -my       Mirror the scene about the xz plane.

       -mz       Mirror the scene about the xy plane.

       -i count  Iterate (repeat) the following transformation (up to the next -i  option)  count
                 times.   This  option  is primarily to support the -a option, which is described
                 below.

   Arrays
       An array is a repeated transformation that results in a repeated object.  It is  specified
       using  the  -a option, which takes the number to repeat as its argument.  The objects will
       step by the transformation given between this -a option and the next -a or -i option.  The
       first  object  will  have  zero applications of the transform.  A two-dimensional array is
       given by two different transformations each preceded by an array count.

EXAMPLE

       To rotate ``book'' 30 degrees about the x axis then move 20  in  y,  prepending  the  name
       book1:

         xform -n book1 -rx 30 -t 0 20 0 book > book1

       To expand all commands and see what information is actually used by RADIANCE:

         xform scene | more

       To  create a two-dimensional array of 20 lights, after an initial rotation and followed by
       a global translation (no command expansion):

         xform -c -rz 90 -a 5 -t 2 0 0 -a 4 -t 0 1.5 0 -i 1 -t 0 0 10 light

ENVIRONMENT

       RAYPATH        path to search for scene files

AUTHOR

       Greg Ward

BUGS

       Only regular (distortion-free) transformations are allowed.

SEE ALSO

       genrbox(1), gensurf(1), oconv(1), replmarks(1), rpict(1), rvu(1)