2.11BSD#431 - /usr/src/games/trek/compkl.c

   1: /*
   2:  * Copyright (c) 1980 Regents of the University of California.
   3:  * All rights reserved.  The Berkeley software License Agreement
   4:  * specifies the terms and conditions for redistribution.
   5:  */
   6: 
   7: #ifndef lint
   8: static char sccsid[] = "@(#)compkl.c	5.1 (Berkeley) 5/30/85";
   9: #endif not lint
  10: 
  11: # include   "trek.h"
  12: 
  13: /*
  14: **  compute klingon distances
  15: **
  16: **	The klingon list has the distances for all klingons recomputed
  17: **	and sorted.  The parameter is a Boolean flag which is set if
  18: **	we have just entered a new quadrant.
  19: **
  20: **	This routine is used every time the Enterprise or the Klingons
  21: **	move.
  22: */
  23: 
  24: compkldist(f)
  25: int f;      /* set if new quadrant */
  26: {
  27:     register int        i, dx, dy;
  28:     double          d;
  29:     double          temp;
  30: 
  31:     if (Etc.nkling == 0)
  32:         return;
  33:     for (i = 0; i < Etc.nkling; i++)
  34:     {
  35:         /* compute distance to the Klingon */
  36:         dx = Ship.sectx - Etc.klingon[i].x;
  37:         dy = Ship.secty - Etc.klingon[i].y;
  38:         d = dx * dx + dy * dy;
  39:         d = sqrt(d);
  40: 
  41:         /* compute average of new and old distances to Klingon */
  42:         if (!f)
  43:         {
  44:             temp = Etc.klingon[i].dist;
  45:             Etc.klingon[i].avgdist = 0.5 * (temp + d);
  46:         }
  47:         else
  48:         {
  49:             /* new quadrant: average is current */
  50:             Etc.klingon[i].avgdist = d;
  51:         }
  52:         Etc.klingon[i].dist = d;
  53:     }
  54: 
  55:     /* leave them sorted */
  56:     sortkl();
  57: }
  58: 
  59: 
  60: /*
  61: **  sort klingons
  62: **
  63: **	bubble sort on ascending distance
  64: */
  65: 
  66: sortkl()
  67: {
  68:     struct kling        t;
  69:     register int        f, i, m;
  70: 
  71:     m = Etc.nkling - 1;
  72:     f = 1;
  73:     while (f)
  74:     {
  75:         f = 0;
  76:         for (i = 0; i < m; i++)
  77:             if (Etc.klingon[i].dist > Etc.klingon[i+1].dist)
  78:             {
  79:                 bmove(&Etc.klingon[i], &t, sizeof t);
  80:                 bmove(&Etc.klingon[i+1], &Etc.klingon[i], sizeof t);
  81:                 bmove(&t, &Etc.klingon[i+1], sizeof t);
  82:                 f = 1;
  83:             }
  84:     }
  85: }

Defined functions

Defined variables