
 Sub-part, Introduction
 
 In QD3D,  the users  work is  filed in a QD3D ``part file'' as a
 part. The user can read this information back into the work area
 in one of two ways:
 
    1.  As a part. The information is retrieved exactly as it was
        stored. This  is exactly  equivalent to reading in a sub-
        drawing in QikDraw 2D.
 
    2.  As a  sub-part. The part previously stored can be read in
        as one  entity, a sub-part. It can be retrieved in at any
        angle and  any scaling  along any of the three coordinate
        axes. A  sub-part is  an actual  QD3D element, and unless
        unpacked, can  be  treated  as  one  element,  ie  moved,
        changed, deleted etc.
 
 Thus sub-parts  are old  parts that  are read  into the  current
 working area as one complete entity. They can be read again from
 the part  file into  the current working area at any angle, size
 or axes scale.
 
 They can  be deleted or manipulated as separate elements and can
 be unpacked into their component lines, points, circles, curves,
 planes, cylinders, revolved arcs and paths.
 
 When a  sub-part is added to the working area, only one point is
 added, the  sub-part reference  point. Sub-parts  are located by
 snapping to their reference point.
 
 
 "SUB ADD"
 
 This command  allows the  user to  add a sub-part to the current
 working area.  He/she must  specify the  part file to select the
 sub-part from, then choose the sub-part from that file. The sub-
 part can be added to the screen at any user specified position.
 
 Procedure
   . Select the part file in tertiary menu to read the part from.
   . Select the sub-part from the list in tertiary menu.
   . Locate the point on the screen to place the part.
 
 This sub-part,  when added,  will consist of only one point, its
 sub-part reference  point. It  can be manipulated as a sub-part,
 ie. as  one entity,  and can  also be  unpacked  into  component
 entities and  points. Once unpacked, it can no longer be treated
 as a  sub-part, but  its component  entities can  be  separately
 manipulated.
 
 
 "SUB DEL"
 
 This command  is used  to delete  a sub-part  from  the  current
 working area.  To select  a sub-part,  the user must snap to the
                                                      ____       
 sub-part reference  point. If  this point cannot be seen, select
 DRAW POINT and then SUB DEL.
 
 
 "SUB UNPCK"
 
 A sub-part  can be  unpacked into component entities if desired.
 Once  a   sub-part  has  been  unpacked  it  can  no  longer  be
 manipulated as  a sub-part  but only  as component  entities and
 points.

 
 "SUB CHANG"
 
 A sub-part  can be  changed to  reflect the  current colour  and
 layer definitions. This is the same as for circles. Refer to 5.5
 CIRCL CHANG for details.
 
 
 "SUB SPECI"
 
 When this  command is  selected, a display of options appears in
 tertiary menu. The user can change any of the default attributes
 given to a sub-part when it is read in.
 
 When a  sub-part is read into the current drawing, the X,Y and Z
 axes ratios  are defined  at a  ratio of  1:1:1, by default. The
 user may change these ratios if desired. Also the rotation about
 each of  the three axes is set at 0.0 by default. These can also
 be changed.
 
 When the  user selects this command, a tertiary menu flashes up,
 and the user can select at will which properties to alter before
 reading a part into the current working area. These options are:
 
  Option         Nature of Option
 
  X SCALE        Resets the X scale ratio.
 
  Y SCALE        Resets the Y scale ratio.
 
  Z SCALE        Resets the Z scale ratio
 
  X ROT          Resets the  rotation about the X axis of the part.
 
  Y ROT          Resets the  rotation about the Y axis of the part.
 
  Z ROT          Resets the  rotation about the Z axis of the part.
 
  COLOUR         The  sub-part  can  be  retrieved  with  the
                 colours it  had  when  stored  or  with  the
                 current colour definition.
 
 The user  just selects  one of  these  from  tertiary  menu  and
 supplies a  new value.  When  finished,  the  user  presses  the
 termination button.
 termination        
 
 Thus any  sub-part read  from a  part file using the command SUB
 ADD will be added according to the current definitions set using
 this command.
 
 
 "SUB TRANS"
 
 This command  provides a convenient method of translating a sub-
 part.   The  sub-part  must  be  located  and  then  two  points
 specified to imply a translation vector.


