Re-use of Drafting Points

In order for a DRAG command to drag a group of primitives that have the same initial position they must share a drafting point. The primitives that do so can be listed using the Q COMMON command or flashed by the HIGHLIGHT COMMON command. The use of a shared drafting point can be achieved:

• When a drafting point is created without specifying its position it is positioned using the default drafting point and is normally the last point used. (It applies to the initial node for a Straight or an Arc.) For example the series of commands:

  NEW CIRC RAD 50 AT @

  NEW CIRC RAD 25

  NEW ARC TCODE centre RAD 75 ASUB 90

  creates two concentric circles and a concentric arc. If the arc is moved using the DRAG command then the two circles also move.

• When a primitive is positioned very close to an existing drafting point in the same NOTE, VNOT or SYTM then the point is re-used to position the new primitive. The default tolerance for re-use of points is 1 mm on the Sheet, although some commands (for example, BY) work to a tolerance of 0.001 mm.

• The tolerance used can be controlled by the TOLERANCE command, for example:

  TOLERANCE 0.5 Set tolerance to .5 mm

• TOLERANCE can be reset to its default value by the command:

  TOL DEF

• Control over the TOLERANCE setting is particularly important for the re-input of DATAL macros. The re-use of drafting points within the TOLERANCE limit can lead to unsatisfactory performance when a NOTE contains a large number of points. For example, when Symbol definitions or Backing Sheets are input from macros.

• The current TOLERANCE status and value can be queried by:

  Q TOL

• The current tolerance is also output to file by the RECREATE DISPLAY macro.

If neither of these methods is appropriate, the current primitive must be explicitly positioned on the required drafting point. The drafting points used by a specified primitive can be identified by querying its PTRF attribute (PTFA attribute for a Straight or Arc) or by using the IDDP @ command.

The current primitive can then be positioned on the required drafting point by commands, for example:

ORIGIN  point_identifier   for example, ORIG IDDP@

ORIGIN  IDDP @

FPT point_identifier          for example, FPT IDP@

DRAG TO IDDP @

(The Q IDN @ command can be used to identify the FPT or TPT of a STRAIGHT.)