The graph drawing routines may be freely mixed with those described in
this section which allow the user to control line colour and styles. The
attributes set up by these routines apply modally, i.e, all subsequent
objects (lines, characters and symbols) plotted until the next change in
attributes are affected in the same way. The only exception to this rule
is that characters and symbols are not affected by a change in the line
style, but are always drawn using a continuous line.
Line colour is set using the routine <#1066#>plcol<#1066#> (page #plcol#1067>). The
argument is ignored for devices which can only plot in one colour but some
terminals support line erasure by plotting in colour zero. For HP
plotters, these colours map to the various pens.
Line style is set using the routine <#1068#>plstyl<#1068#> (page #plstyl#1069>). A broken
line is specified in terms of a repeated pattern consisting of marks
(pen down) and spaces (pen up). The arguments to this routine consist of
the number of elements in the line, followed by two pointers to
integer arrays specifying
the mark and space lengths in micrometres. Thus a line consisting of
long and short dashes of lengths 4;SPMnbsp;mm and 2;SPMnbsp;mm, separated by spaces of
length 1.5;SPMnbsp;mm is specified by:
verbatim12#
To return to a continuous line, just call <#902#>plstyl<#902#> with first argument
set to zero.