From 83f1bf37b77899defc5502c22e2bebb029deb0fe Mon Sep 17 00:00:00 2001
From: John Honniball <coredump@virginmedia.com>
Date: Thu, 27 Aug 2020 21:27:28 +0100
Subject: [PATCH] New drawing: cutout_hex, hexagons that are intended to be cut
 out from the page. Note that they don't make the most efficient use of the
 paper -- they don't tesselate. But they can be cut apart using a knife and
 straightedge.

---
 .gitignore   |   1 +
 Makefile     |  11 ++++-
 cutout_hex.c | 117 +++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 128 insertions(+), 1 deletion(-)
 create mode 100644 cutout_hex.c

diff --git a/.gitignore b/.gitignore
index 8c6299a..a3bb7c1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -12,6 +12,7 @@ arches
 celticstep
 circle4
 circle_lines
+cutout_hex
 coords
 coords-nc
 cs_rosette
diff --git a/Makefile b/Makefile
index 1e02d5b..0f823c2 100644
--- a/Makefile
+++ b/Makefile
@@ -23,7 +23,7 @@ HPGL=flake.hpgl op.hpgl dala1.hpgl hconic2.hpgl tree.hpgl dome.hpgl \
      morphpoly.hpgl pin_circle.hpgl isogrid.hpgl circle_lines.hpgl \
      star_grid.hpgl ternary_arcs.hpgl hexspiral.hpgl poly_oval.hpgl \
      libtest.hpgl linetiles.hpgl a6cardlabels.hpgl octoflower.hpgl \
-     circle4.hpgl truchet1.hpgl
+     circle4.hpgl truchet1.hpgl cutout_hex.hpgl
 
 SVG=$(HPGL:.hpgl=.svg)
 
@@ -85,6 +85,15 @@ circle_lines: circle_lines.o hpgllib.o
 circle_lines.o: circle_lines.c hpgllib.h
 	$(CC) $(CFLAGS) -o $@ circle_lines.c
 
+cutout_hex.hpgl: cutout_hex Makefile
+	./cutout_hex $(TITLE) $(BOLDPEN) -o $@
+
+cutout_hex: cutout_hex.o hpgllib.o
+	$(LD) -o $@ cutout_hex.o hpgllib.o -lm
+
+cutout_hex.o: cutout_hex.c hpgllib.h
+	$(CC) $(CFLAGS) -o $@ cutout_hex.c
+
 ellipse.hpgl: ellipse Makefile
 	./ellipse $(TITLE) $(BOLDPEN) -o $@
 
diff --git a/cutout_hex.c b/cutout_hex.c
new file mode 100644
index 0000000..eafcdc3
--- /dev/null
+++ b/cutout_hex.c
@@ -0,0 +1,117 @@
+/* cutout_hex --- plot hexagons that can be cut out easily  2020-08-26 */
+/* Copyright (c) 2020 John Honniball, Froods Software Development      */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+#include <unistd.h>
+#include "hpgllib.h"
+
+#define RADIANS  (M_PI / 180.0)
+
+void hexgrid(const double side, const int nx, const int ny);
+
+int main(int argc, char * const argv[])
+{
+   int opt;
+   double side;
+   double maxx, maxy;
+   
+   while ((opt = getopt(argc, argv, "no:p:s:t:v:")) != -1) {
+      switch (opt) {
+      case 's':
+      case 'n':
+      case 'o':
+      case 'p':
+      case 't':
+      case 'v':
+         plotopt(opt, optarg);
+         break;
+      default: /* '?' */
+         fprintf(stderr, "Usage: %s [-p pen] [-s <size>] [-t title]\n", argv[0]);
+         fprintf(stderr, "       <size> ::= A1 | A2 | A3 | A4 | A5\n");
+         exit(EXIT_FAILURE);
+      }
+   }
+
+   if (plotbegin(1) < 0) {
+      fputs("Failed to initialise HPGL library\n", stderr);
+      exit(EXIT_FAILURE);
+   }
+
+   getplotsize(&maxx, &maxy);
+   
+// side = 50.08 * 40.0;
+// hexgrid(side, 4, 2);
+   side = 45.0 * 40.0;
+   hexgrid(side, 5, 3);
+
+   plotend();
+   
+   return (0);
+}
+
+   
+void hexgrid(const double side, const int nx, const int ny)
+{
+   int i, j;
+   const double width = 2.0 * side * cos(30.0 * RADIANS);
+   
+   for (i = 0; i < ny; i++) {
+      const double y = 2.0 * side * (double)i;
+      const double y1 = y + (side * sin(30.0 * RADIANS));
+#ifdef TRISECT
+      const double y2 = y + side;
+#endif
+      const double y3 = y1 + side;
+      const double y4 = y + (2.0 * side);
+      
+      for (j = 0; j < nx; j++) {
+         const double x = width * (double)j;
+         const double x1 = x + (side * cos(30 * RADIANS));
+         const double x2 = x + width;
+         
+         moveto(x, y1);
+         lineto(x1, y);
+         lineto(x2, y1);
+      }
+   
+      for (j = 0; j < (nx + 1); j++) {
+         const double x = width * (double)j;
+         
+         moveto(x, y1);
+         lineto(x, y3);
+      }
+
+      for (j = 0; j < nx; j++) {
+         const double x = width * (double)j;
+         const double x1 = x + (side * cos(30 * RADIANS));
+         const double x2 = x + width;
+         
+         moveto(x, y3);
+         lineto(x1, y4);
+         lineto(x2, y3);
+      }
+
+#ifdef TRISECT
+      for (j = 0; j < nx; j++) {
+         const double x = width * (double)j;
+         const double x1 = x + (side * cos(30 * RADIANS));
+         const double x2 = x + width;
+         
+         moveto(x, y1);
+         lineto(x1, y2);
+         lineto(x2, y1);
+      }
+
+      for (j = 0; j < nx; j++) {
+         const double x = width * (double)j;
+         const double x1 = x + (side * cos(30 * RADIANS));
+         
+         moveto(x1, y2);
+         lineto(x1, y4);
+      }
+#endif
+   }
+}