Function:ss2qcf

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Revision as of 01:21, 4 December 2007

ss2qcf

Query camera focus point and state.

Prototype

Description

Query the camera focus point, and whether it is explicitly set. The return value of set indicates whether focus is "set" or "unset" - see functions ss2scf and ss2ucf. The position of the camera focus point is returned in position. Coordinates will be returned in world coordinates if the worldcoords argument is non-zero.

See Also

ss2scfSet the camera mid/focus point.
ss2scfUnset the camera mid/focus point - return to auto mid-point

Code Example

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

void cb(double *t, int *kc)
{
   static int lkc = 0;                  /* Local state of key press */
   XYZ pos, up, vd, foc;                /* Camera and focus vectors */
   static float dz = +0.05;             /* Amount to move camera/focus by */
   int wc = 1;                          /* Use world coordinates */
   int set;                             /* Flag returning focus mode */

   ss2qcf(&set, &foc, wc);              /* Query camera focus point */
   if (set) {                           /* If set manually */
      ss2qc(&pos, &up, &vd, wc);        /* Query camera location */
      if (pos.z > 5) {                  /* Check bounds of camera and */
         dz = -0.05;                    /*  turn motion around if needed */
      } else if (pos.z < 0) {
         dz = +0.05;
      }

      pos.z += dz;                      /* Update the camera location */
      ss2sc(pos, up, vd, wc);           /* Set the new camera position */

      foc.z += dz;                      /* Update the focus location */
      ss2scf(foc, wc);                  /* Set the new focus position */
   }
   if (lkc != *kc) {                    /* If <spacebar> has been pressed */
      if (lkc % 2) {                    /*  since last display, toggle */
         ss2scf(foc, wc);               /*  state of auto motion */
      } else {
         ss2ucf();                      /* Return to auto focus point */
      }
   }
   lkc = *kc;                           /* Update key press value */

}

int main(int argc, char *argv[])
{
   int i, N = 20;                       /* Loop variables */
   float x, y, z;                       /* Random data */
   XYZ focus;                           /* Point to rotate about */
   int wc = 1;                          /* Use world coordinates */

   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 */

   s2slw(3);                            /* Set line width */
   for (i=0;i<N;i++) {
      x = drand48()*2.0 - 1.0;          /* Random (x,y,z) */
      y = drand48()*2.0 - 1.0;
      z = drand48()*2.0 - 1.0;
      s2sci(15*drand48() + 1);          /* Random colour */
      s2pt1(x,y,z,1);                   /* Plot the point */
   }
   focus.x = focus.y = focus.z = 0.0;   /* Initial camera focus values */

   ss2scf(focus, wc);                   /* Set the camera focus location */
   s2textxy(-1,0,0,"Press <space> to toggle motion");

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

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

   return 1;
}

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