DRAW Reference Manual
2D Drafting : 2D Drafting Primitives : Re-use of Drafting Points
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 may be listed using the Q COMMON command or flashed by the HIGHLIGHT COMMON command. The use of a shared drafting point may be achieved in one of the following ways:
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When a drafting point is created without specifying its position it will be positioned using the default drafting point. This is normally the last point used. (This 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
would create two concentric circles and a concentric arc. If the arc were moved using the DRAG command then the two circles would also move.
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When a primitive is positioned very close to an existing drafting point in the same NOTE, VNOT or SYTM then the point will be re-used to position the new primitive. The default tolerance for re-use of points is 1 mm on the Sheet, although some commands (e.g. BY) work to a tolerance of 0.001 mm.
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The tolerance used may be controlled by the TOLERANCE command, for example:
TOLERANCE 0.5 Set tolerance to .5 mm
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TOLERANCE may be reset to its default value by the command
TOL DEF
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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. This may happen, for example, when Symbol definitions or Backing Sheets are input from macros.
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The current TOLERANCE status and value may be queried by
Q TOL
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The current tolerance will also be 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 may be identified by querying its PTRF attribute (PTFA attribute for a Straight or Arc) or by using the IDDP @ command.
The current primitive may then be positioned on the required drafting point by commands such as:
ORIGIN  point_identifier,   e.g. ORIG IDDP@
ORIGIN  IDDP @
FPT point_identifier          e.g. FPT IDP@
DRAG TO IDDP @
(The Q IDN @ command may be used to identify the FPT or TPT of a STRAIGHT.)
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