Function:ss2qbc

void ss2qbc(float *r, float *g, float *b);

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

void cb(double *t, int *kc)
{
   static int lkc = 0;                          /* Count of key presses */

   if (lkc != *kc) {                            /* Space bar pressed? */
     ss2sbc(drand48(), drand48(), drand48());   /* Random background colour */
   }
   float r, g, b;
   ss2qbc(&r, &g, &b);                          /* Query background colour */
   
   s2scr(100,1-r,1-g,1-b);
   s2sci(100);
   char string[32];                     
   sprintf(string,"Colour = (%.2f,%.2f,%.2f)",r,g,b);   /* Write to string */
   s2textxy(0,-0.5,0,string);                   /* Display text */

   lkc = *kc;                                   /* Update count */
}

int main(int argc, char *argv[])
{
   fprintf(stderr,"Press the <spacebar> to change background colour");

   s2opend("/s2mono", argc, argv);              /* Open in mono mode */
   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 dynamic callback */
   s2show(1);                                   /* Open the s2plot window */

   return 1;
}