Function:ss2qca

float ss2qca(void);

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include "s2plot.h"

void cb(double *t, int *kc)
{
   int N = 100;                                 /* Number of points */
   static int flag = -1;                        /* Flag for initialisation */
   static XYZ xyz[100];                         /* Array of point positions */
   static COLOUR col[100];                      /* Array of colours */
   int i;                                       /* Loop variable */

   if (flag < 0) {                              /* First time through? */
      for (i=0;i<N;i++) {
         xyz[i].x = drand48()*2.0 - 1.0;        /* Random data positions */
         xyz[i].y = drand48()*2.0 - 1.0;
         xyz[i].z = drand48()*2.0 - 1.0;
         col[i].r = drand48();                  /* Random data colours */
         col[i].g = drand48();
         col[i].b = drand48();
      }
      flag = 1;                                 /* Set the flag */
   }

   for (i=0;i<N;i++) {
      ns2vthpoint(xyz[i], col[i], 3);           /* Draw the point */
   }

   static int lkc = 1;                          /* Last time <space> key pressed */
   if (lkc != *kc)                              /* Check for keyboard press */
      ss2sca(drand48()*70 + 20);                /* Set the camera aperture */
   lkc = *kc;                                   /* Update key press */

   int wc = ss2qca();                           /* Query camera aperture */
   char text[64];
   sprintf(text, "Aperture %d degrees\n",wc);   /* Prepare a text string */
   s2textxy(0.0,0.0,0.0, text);                 /* Display text string */

   s2lab("","","","Press <space> to change camera aperture");
}

int main(int argc, char *argv[])
{

   srand48((long)time(NULL));                   /* Seed random numbers */

   s2opend("/?",argc, argv);                    /* Open the display */
   s2swin(-1.,1., -1.,1., -1.,1.);              /* Set the window coordinates */
   s2box("BCDET",0,0,"BCDET",0,0,"BCDET",0,0);  /* Draw coordinate box */

   cs2scb(cb);                                  /* Install a dynamic callback */

   s2show(1);                                   /* Open the s2plot window */


   return 1;
}