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)

RADIANCE                                             6/4/99                                             XFORM(1)