
  Path, Introduction
  
  A path  is an element designed for use in dynamic viewing. It is
  composed of a sequence of contiguous or disjoint lines, plus one
  orientation vector  which represents  the vertical  direction on
  the screen. After a path has been added, the command UTILI DYNAM
  permits the  user's eye point to move around or through a model,
  i.e. a dynamic ``walk through''.
  
  
  "PATH ADD"
  
  When this  command is  selected you  will be prompted to type an
  upwards direction. The direction [0 0 1] is usually satisfactory
  if the  model's base  is in  the x-y  plane. You  will  then  be
  prompted for  the starting point of the path, for which you must
  snap to  one end  of a line. Then you will be prompted to locate
  an adjoining  line and  then another  and so  on. An unconnected
  line can be located if one desires a discontinuity in the path.
  
   Press  the terminate button when you have located enough lines.
  You will  then be asked if you wish to start a disjoint path and
  if you want to delete the lines which you selected (so that they
  are absent from the picture).
  
  
  "PATH DEL"
  
  A path  can be  deleted by  snapping to  one of  its  definition
  points.
  
  
  "PATH CHANG"
  
  This command  allows the  colour and  layer  of  a  path  to  be
  changed. The  procedure for  its use  is the  same as  for POINT
  CHANG.


