Add line styles to the HPGL library.

Not used by any of the drawings yet though.

TODO.md

@@ -19,8 +19,6 @@ the library and/or command line (we just use 9600 baud).
 SIGINT has stopped a plot.
 * Make 'plotcancel()' work properly. Install a signal handler in 'plotbegin()'
 to call it if/when we get a signal.
-* Add support for line styles. We could use dotted and dashed lines
-for some of the plots, e.g. fold lines, centre lines.
 * Add support for read-back commands when the interface allows them.
 E.g. 'OS', 'OA' and 'OI'.
 * Add support for automatic paper feed on HP 7550 and any other plotters
@@ -97,6 +95,7 @@ command-line arguments and low-level driver code.
 * Add new drawings! Especially colouring-in drawings, all-over patterns,
 3D perspective drawings, maps and even slow-to-draw drawings!
 * Add colour (pen changes) to drawings.
+* Add line styles (dotted, dashed) to drawings.
 * Add drawings that can be folded like Origami.
 * Add drawings that can be cut out and assembled, e.g. geodesic dome,
 packaging such as cake boxes, decorations such as snowflakes.

hpgllib.c

@@ -881,6 +881,17 @@ void pencolr(int c)
 }
 
 
+/**
+ * @brief Set the line type
+ *
+ * @param t The line type to be set
+ */
+void linetype(const int t)
+{
+   fprintf(Plt, "LT%d;\n", t);
+}
+
+
 /**
  * @brief Draw a text label vertically
  *

hpgllib.h

@@ -76,6 +76,7 @@ void arc(const double x, const double y, const double a);
 void ellipse(const double x0, const double y0, const double a, const double b, const double theta);
 void roundrect(const double x1, const double y1, const double x2, const double y2, const double radius);
 void pencolr(int c);
+void linetype(const int t);
 void vlabel(const double x, const double y, const double siz, const char *const str);
 void hlabel(const double x, const double y, const double siz, const char *const str);
 int writedisplay(const char *const str);