New drawing: poly_oval, a polygon made from multiple overlapping oval…

…s. By default, a pentagon but should be possible to add command-line arguments to set number of sides and other variables.

.gitignore

@@ -52,5 +52,6 @@ superellipse
 sutpent
 ternary_arcs
 tree
+poly_oval
 twist
 zigzag

Makefile

@@ -20,7 +20,7 @@ HPGL=flake.hpgl op.hpgl dala1.hpgl hconic2.hpgl tree.hpgl dome.hpgl \
      curve_stitching.hpgl cs_rosette.hpgl allover13.hpgl allover12.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
+     star_grid.hpgl ternary_arcs.hpgl hexspiral.hpgl poly_oval.hpgl
 
 PNG=$(HPGL:.hpgl=.png)
 
@@ -131,6 +131,15 @@ ternary_arcs: ternary_arcs.o hpgllib.o
 ternary_arcs.o: ternary_arcs.c hpgllib.h
 	$(CC) $(CFLAGS) -o $@ ternary_arcs.c
 
+poly_oval.hpgl: poly_oval Makefile
+	./poly_oval $(TITLE) $(BOLDPEN) -o $@
+
+poly_oval: poly_oval.o hpgllib.o
+	$(LD) -o $@ poly_oval.o hpgllib.o -lm
+
+poly_oval.o: poly_oval.c hpgllib.h
+	$(CC) $(CFLAGS) -o $@ poly_oval.c
+
 morphpoly.hpgl: morphpoly Makefile
 	./morphpoly $(TITLE) $(BOLDPEN) -o $@
 

poly_oval.c

@@ -0,0 +1,109 @@
+/* poly_oval --- plot polygon of ovals                      2020-08-05 */
+/* 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"
+
+struct Point {
+   double x;
+   double y;
+};
+
+void multi_oval(struct Point *p1, struct Point *p2, const double inner, const double outer, const int n);
+void draw_oval(const struct Point *const p1, const struct Point *const p2, const struct Point *const vec90);
+
+int main(int argc, char * const argv[])
+{
+   int opt;
+   int i, j;
+   double xc, yc;
+   double maxx, maxy;
+   double delta;
+   int nsides = 5;
+   double outer = 40.0;
+   double inner = 15.0;
+   struct Point pt[16];
+   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);
+      }
+   }
+
+   plotbegin(1);
+
+   getplotsize(&maxx, &maxy);
+
+   xc = maxx / 2.0;
+   yc = maxy / 2.0;
+
+   delta = (2.0 * M_PI) / (double)nsides;
+   radius = (maxy / 2.0) - (outer * 40.0);
+
+   for (i = 0; i < nsides; i++) {
+      const double theta = (double)i * delta;
+
+      pt[i].x = xc + (radius * cos(theta));
+      pt[i].y = yc + (radius * sin(theta));
+   }
+
+   for (i = 0; i < nsides; i++) {
+      j = (i + 1) % nsides;
+
+      multi_oval(&pt[i], &pt[j], inner * 40.0, outer * 40.0, 12);
+   }
+
+   plotend();
+
+   return (0);
+}
+
+
+void multi_oval(struct Point *p1, struct Point *p2, const double inner, const double outer, const int n)
+{
+   int i;
+   struct Point vec;
+   struct Point vec90;
+   const double dx = p1->x - p2->x;
+   const double dy = p1->y - p2->y;
+   const double mag = sqrt((dx * dx) + (dy * dy));
+   const double delta_r = (outer - inner) / (double)(n - 1);
+
+   vec.x = dx / mag;
+   vec.y = dy / mag;
+
+   for (i = 0; i < n; i++) {
+      const double r = inner + (i * delta_r);
+
+      vec90.x = vec.y * r;
+      vec90.y = -vec.x * r;
+
+      draw_oval(p1, p2, &vec90);
+   }
+}
+
+
+void draw_oval(const struct Point *const p1, const struct Point *const p2, const struct Point *const vec90)
+{
+   moveto(p1->x + vec90->x, p1->y + vec90->y);
+   arc(p1->x, p1->y, 180.0);
+   lineto(p2->x - vec90->x, p2->y - vec90->y);
+   arc(p2->x, p2->y, 180.0);
+   lineto(p1->x + vec90->x, p1->y + vec90->y);
+}