www.pudn.com > CG2Programs.rar > drawCurlyFig.c

/* drawCurlyFig, Chapter 3, pp. 139-140 */

/* EXAMPLE STARTS HERE */
#include 
#include 
#include "graphics.h"

#define TWO_PI 6.28

/* Limacon equation is r = a * cos(theta) + b.  Cardioid is the same,
   with a == b, so r = a * (1 + cos(theta)).
*/
typedef enum { spiral, cardioid, threeLeaf, fourLeaf, limacon } Fig;

void drawCurlyFig (Fig figure, wcPt2 pos, int * p)
{
  float r, theta = 0.0, dtheta = 1.0 / (float) p[0];
  int nPoints = (int) ceilf (TWO_PI * p[0]) + 1;
  wcPt2 * pt;

  if ((pt = (wcPt2 *) malloc (nPoints * sizeof (wcPt2))) == NULL) {
    fprintf (stderr, "Couldn't allocate points\n");
    return;
  }

  /* Set first point for figure */
  pt[0].y = pos.y;
  switch (figure) {
  case spiral:    pt[0].x = pos.x;               break;
  case limacon:   pt[0].x = pos.x + p[0] + p[1]; break;
  case cardioid:  pt[0].x = pos.x + p[0] * 2;    break;
  case threeLeaf: pt[0].x = pos.x + p[0];        break;
  case fourLeaf:  pt[0].x = pos.x + p[0];        break;
  }
  nPoints = 1;
  while (theta < TWO_PI) {
    switch (figure) {
    case spiral:    r = p[0] * theta;               break;
    case limacon:   r = p[0] * cosf (theta) + p[1]; break;
    case cardioid:  r = p[0] * (1 + cosf (theta));  break;
    case threeLeaf: r = p[0] * cosf (3 * theta);    break;
    case fourLeaf:  r = p[0] * cosf (2 * theta);    break;
    }
    pt[nPoints].x = pos.x + r * cosf (theta);
    pt[nPoints].y = pos.y + r * sinf (theta);
    nPoints++;
    theta += dtheta;
  }
  
  pPolyline (nPoints, pt);
  free (pt);
}

void main (int argc, char ** argv)
{
  long windowID = openGraphics (*argv, 400, 100);
  Fig f;
  /* Center positions for each figure */
  wcPt2 center[] = { 50, 50, 100, 50, 175, 50, 250, 50, 300, 50 };

  /* Parameters to define each figure.  First four need one parameter.
     Fifth figure (limacon) needs two. */
  int p[5][2] = { 5, -1, 20, -1, 30, -1, 30, -1, 40, 10 };

  setBackground (WHITE);
  setColor (BLACK);
  for (f=spiral; f<=limacon; f++) 
    drawCurlyFig (f, center[f], p[f]);
  sleep (10);
  closeGraphics (windowID);
}
/* EXAMPLE ENDS HERE */