src/lib/math.c

   1 /************************************************************************
   2 * math.c
   3 * voxelands - 3d voxel world sandbox game
   4 * Copyright (C) Lisa 'darkrose' Milne 2016 <lisa@ltmnet.com>
   5 *
   6 * This program is free software: you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License as published by
   8 * the Free Software Foundation, either version 3 of the License, or
   9 * (at your option) any later version.
  10 *
  11 * This program is distributed in the hope that it will be useful, but
  12 * WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  14 * See the GNU General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU General Public License
  17 * along with this program.  If not, see <http://www.gnu.org/licenses/>
  18 ************************************************************************/
  19
  20 #include "common.h"
  21
  22 #include <math.h>
  23 #include <time.h>
  24 #include <stdlib.h>
  25
  26 /* get the next power of 2 */
  27 int math_next_pow2(int a)
  28 {
  29         int rval = 2;
  30
  31         while (rval<a) {
  32                 rval <<= 1;
  33         }
  34
  35         return rval;
  36 }
  37
  38 /* return a random number between low and high */
  39 int math_rand_range(int low, int high)
  40 {
  41         static int rand_seeded = 0;
  42         int x;
  43         int n = (high-low)+1;
  44         int rand_limit;
  45         int rand_excess;
  46
  47         if (low >= high)
  48                 return low;
  49
  50         if (!rand_seeded) {
  51                 srand((unsigned int)time(NULL));
  52                 rand_seeded = 1;
  53         }
  54
  55         rand_excess = ((int64_t)RAND_MAX + 1) % n;
  56         rand_limit = RAND_MAX - rand_excess;
  57         while ((x = rand()) > rand_limit);
  58
  59         return (x % n)+low;
  60 }
  61
  62 /* return a random number between low and high */
  63 float math_rand_rangef(float low, float high)
  64 {
  65         int r = math_rand_range(low*1000,high*1000);
  66         return (float)r/1000.0;
  67 }
  68
  69 /* convert radians to degrees */
  70 float math_radians_to_degrees(float rads)
  71 {
  72         return rads*(180.0*M_PI);
  73 }
  74
  75 /* convert degrees to radians */
  76 float math_degrees_to_radians(float degrees)
  77 {
  78         return degrees*(M_PI/180.0);
  79 }