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<EXTENT-LIMIT value>
<FIXED|NOFIXED>
<LINE-VECTOR dx dy dz>
<HEIGHT value>
<PATH-VECTOR dx dy dz>
<PEN-DIAMETER value>
<RIGHT-VECTOR dx dy dz>
<SPACE value>
<STRING-JUSTIFICATION (CENTER|FIRST|LAST|LEFT|OFF|RIGHT)>
<UP-VECTOR dx dy dz>
<WIDTH-SCALE value>
This command provides access to the full generality of the <PLOT79>
character and text specification. The order of the options is not
important, except as noted below for the LINE keyword. The vectors dx
dy dz define a direction, and their magnitude is not significant. It
is an error to specify dx dy dz = 0 0 0, since this does not define a
direction. Omitted options simply leave the current values in effect;
they do NOT cause them to be reset to their default values.
The character height is measured in the current world coordinates units
as determined by the current window boundaries. The width scale factor
is by default 1.0 and should normally be omitted. It scales the normal
character width, so that a value of 0.80 will give characters 20
percent narrower than the font designer intended.
Normally, if a text line is too long to fit on the current line, the
character height will temporarily be reduced to make it fit within the
current window. This action may be suppressed if the keyword FIXED is
specified; the text outside the current line will then simply be
truncated. The keyword NOFIXED causes a reversion to the default
action of reducing to obtain a fit. If neither FIXED nor NOFIXED is
specified, the option is unchanged from its previous value. The
EXTENT-LIMIT value can be used to force temporary character height
reduction to make the string fit within the specified extent measured
along the character path. In either case, a message is typed giving
the value of the reduced height so that it can be used later to reset
the character height parameter.
The BOX-JUSTIFICATION option sets the justification of the character
box according to the specified keyword. The character path lies along
one of four baselines passing through the character box. BOTTOM means
the lower limit of the character box, below any letter descenders. OFF
means the character path passes through the baselines of upper-case
letters. CENTER means the baseline passing through the center of most
characters. TOP means the baseline just touching the tops of most
upper-case letters. The default justification is "OFF" which will be
assumed if no CHARACTER BOX-JUSTIFICATION command is ever specified.
The STRING-JUSTIFICATION option set the justification of the entire
character string according to the specified keyword. FIRST, LEFT, and
OFF are equivalent and align the beginning edge of the first character
at the current point. LAST and RIGHT are equivalent and align the
ending edge of the last character box at the current point. The
default string justification is CENTER, which results in the character
string being centered at the current point.
Characters are normally written horizontally from left to right,
corresponding to the default options
PATH-VECTOR 1 0 0
RIGHT-VECTOR 1 0 0
UP-VECTOR 0 1 0
The vectors dx dy dz specified with the PATH-VECTOR, RIGHT-VECTOR, and
UP-VECTOR options define the character string path, the character box
right direction, and the character box up direction, respectively, the
direction dx dy dz being relative to the lower-left corner of a
character box. PATH-VECTOR and RIGHT-VECTOR should normally be
identical, with UP-VECTOR perpendicular to them. However, a
specification like
PATH-VECTOR 1 0 0
RIGHT-VECTOR -1 0 0
will result in mirror-image characters;
PATH-VECTOR 0 -1 0
RIGHT-VECTOR 1 0 0
UP-VECTOR 0 1 0
will give vertical columns of characters; and
PATH-VECTOR 1 0 0
RIGHT-VECTOR 1 0 0
UP-VECTOR 0.1 1 0
will give slanted characters on horizontal lines. If character paths
other than the default 1 0 0 are used, then it will usually be
necessary to explicitly position text with MOVE commands, since the new
current point computed by the TEXT command is based on the assumption
that horizontal lines of text are being drawn in vertical columns.
When a line of text is drawn by the text command, the current point is
updated by moving in the direction of the LINE-VECTOR option vector dx
dy dz a distance proportional to the current character height. This
vector is by default 0 -1 0, and should generally be perpendicular to,
and pointing below, the character string path. That is, it should
normally point in the direction pathy -pathx 0. For user convenience,
the PATH-VECTOR option will always set it to this value, so if an
alternate value is desired, it must be specified AFTER the PATH option.
The PEN-DIAMETER option allows one to simulate a thick pen when text is
drawn. Each character is drawn repeatedly, stepping its origin around
a small circle representing the pen diameter. For convenience, the
diameter value is given as a fraction of the character height, rather
than as an absolute number. A value of about 0.01 to 0.03 often gives
reasonable results. A value of 0.0 will revert to normal text
plotting.
The SPACE option may be used to alter the usual inter-character
spacing. The default value is 0.0; a value of +0.10 will increase the
normal spacing by 10 percent, while a value of -0.10 will decrease it
by the same amount.