New drawing: octoflower, an 8-petal flower. Could be made parametric …

…(number of petals, number of layers). Does not scale properly yet. Draws each petal in turn, whereas it may look better of we draw all the petals for one layer, then the next layer, an so on.

.gitignore

@@ -37,6 +37,7 @@ lissajous
 lobe
 lotus
 morphpoly
+octoflower
 op
 op_moire
 pappus
@@ -46,6 +47,7 @@ piscis
 pin_and_cotton
 pin_circle
 plottext
+poly_oval
 qrplot
 rtree
 spiralsq
@@ -56,6 +58,5 @@ superellipse
 sutpent
 ternary_arcs
 tree
-poly_oval
 twist
 zigzag

Makefile

@@ -22,7 +22,7 @@ HPGL=flake.hpgl op.hpgl dala1.hpgl hconic2.hpgl tree.hpgl dome.hpgl \
      qrplot.hpgl lotus.hpgl celticstep.hpgl op_moire.hpgl sutpent.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
+     libtest.hpgl linetiles.hpgl a6cardlabels.hpgl octoflower.hpgl
 
 SVG=$(HPGL:.hpgl=.svg)
 
@@ -282,6 +282,15 @@ celticstep: celticstep.o hpgllib.o
 celticstep.o: celticstep.c hpgllib.h
 	$(CC) $(CFLAGS) -o $@ celticstep.c
 
+octoflower.hpgl: octoflower Makefile
+	./octoflower $(TITLE) $(BOLDPEN) -o $@
+
+octoflower: octoflower.o hpgllib.o
+	$(LD) -o $@ octoflower.o hpgllib.o -lm
+
+octoflower.o: octoflower.c hpgllib.h
+	$(CC) $(CFLAGS) -o $@ octoflower.c
+
 op_moire.hpgl: op_moire Makefile
 	./op_moire $(TITLE) $(BOLDPEN) -o $@
 

octoflower.c

@@ -0,0 +1,97 @@
+/* octoflower --- plot an eight-petal flower                2020-08-23 */
+/* 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"
+
+void draw_petal(const double xc, const double yc, const double delta, const double theta, const double radius);
+
+int main(int argc, char * const argv[])
+{
+   int opt;
+   int i;
+   double xc, yc;
+   double maxx, maxy;
+   double delta;
+   int npetals = 8;
+   double radius;
+
+   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);
+
+   xc = maxx / 2.0;
+   yc = maxy / 2.0;
+
+   delta = (2.0 * M_PI) / (double)npetals;
+   radius = (maxy / 3.0);
+
+   for (i = 0; i < npetals; i++) {
+      const double theta = (double)i * delta;
+
+      const double x = xc + (radius * cos(theta));
+      const double y = yc + (radius * sin(theta));
+
+      moveto(xc, yc);
+      lineto(x, y);
+   }
+
+   for (i = 0; i < npetals; i++) {
+      const double theta = delta * (double)i;
+
+      draw_petal(xc, yc, delta, theta, radius);
+   }
+
+   plotend();
+
+   return (0);
+}
+
+
+void draw_petal(const double xc, const double yc, const double delta, const double theta, const double radius)
+{
+   int i;
+   const double tipx = xc + (radius * cos(theta));
+   const double tipy = yc + (radius * sin(theta));
+
+   for (i = 1; i <= 6; i++) {
+      const double len = 4.0 * 40.0 * (double)i;
+      const double offx = len * sin(theta);
+      const double offy = -len * cos(theta);
+      const double arcx = tipx + offx;
+      const double arcy = tipy + offy;
+
+      const double baslen = len / tan(delta / 2.0);
+      const double basx = baslen * cos(theta);
+      const double basy = baslen * sin(theta);
+
+      moveto(xc + basx + offx, yc + basy + offy);
+      lineto(arcx, arcy);
+      arc(tipx, tipy, 180.0);
+      lineto(xc + basx - offx, yc + basy - offy);
+   }
+}