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- LINE MANIPULATIONS
- ******************
-
- OPTIONS:- The following line options are available:-
- Rectangular box;
- Lines tangent to circles (internal or external);
- Extending/shrinking two lines to meet at a point;
- Trimming one line with respect to another;
- Perpendiculars from points to (or away from) reference
- line/arc;
- Bisecting angles or lines;
- Line with a bend and terminating arrow;
- Swapping the direction definition of a line.
- ADD:- Lines may be added in SNAP or NOSNaP (see MODE) mode.
- If the Key-Board is selected as the primary entry device,
- the user can type in co-ordinates of the end points
- defining the lines. The co-ordinates are absolute by
- default. However, the input may be prefixed by the
- characters M,R or P (or any of their combinations). M
- means move, R means relative & P means polar (distance,
- angle in degrees).
- If the "LINE ADD" command has been selected by pressing
- the LEFT button, locations selected will either snap to
- line/line intersectn points or vertices of symbols,
- wherever the tolerance is not exceeded.
- DELETE:- Lines may be deleted by locating the pointer close to the
- line to be deleted. Be careful to avoid possible ambiguity.
- If selected with the LEFT button, the user will be offered
- the option to delete all construction lines or else
- delete lines in reverse order of storage.
- STRETCH:- A line can be stretched along its own length without
- altering its orientation. If selected with LEFT button,
- option to extend lines to infinity.
- STYLE:- Various line styles can be specified.
- Line styles with embedded symbols are also supported.
- If selected with the LEFT PUCK button, the length of repeat
- of non-solid lines can be specified.
- CHANGE:- Line specifications can be altered by selecting this
- option and then locating the line to be changed. The
- specifications (pen, thickness, style, terminators) for
- the line will then be changed to those currently defined.
- Alternate selection allows for the change of PEN NUMBER
- only, or line style and thickness only. This selection
- also allows for changes in GLOBAL mode.
- PEN:- The user will be prompted for a pen number.
- The tertiary menu for line thickness would then be
- displayed, and a selection requested.
- CONSTRUCTION LINES are those lines that will not appear on
- a DRAW ALL (or final plot) command.
- MERGE:- Merge two lines (end points must be co-linear).
- Alternate selection allows for merging a block
- of lines.
- //:- Lines may be specified parallel to a reference line at
- prescribed distances or passing through arbitary locations.
- Alternate selection allows for generation of a pair of
- lines at prescribed off-set (start & end) from the
- reference line (open or closed at ends).
- BREAK:- Points lying on a line does not imply that the line has
- been divided into segments. This option will divide the
- line into segments according to the number of points lying
- on the line.
- Alternate selection with the LEFT button allows the
- erasure of part of the line. This portion may be specified
- as centred between the end points of the line.
- ALIGN:- This option allows the alignment of lines. The line to be
- changed will be made parallel to and at a specified
- distance from the reference line. The new end points will
- be the projections of the old end points onto the new line.
- OOPS if LEFT button pressed.
- If option selected with the LEFT button, the old end pts
- will be moved to new positions without altering connected
- entities.
- TERMI:- Terminators can be specified for a line. This is very much
- more efficient then specifying them separately.
- ANGLE:- This will force the lines added to be at a specific angle
- (or multiples there-of). Thus, setting angle to 90 would
- cause all lines to be orthogonal except when snapping to
- an existing point. The constraint can be relative to the
- X-axis or a direction defined by a line.