src/map/mapgen_noise.c

   1 /************************************************************************
   2 * mapgen_noise.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
  24 static int seed = 12345;
  25
  26 static float noise(int x, int z)
  27 {
  28         int a = (x*43695)+(z*43721)+seed;
  29         int b = (a>>13)^a;
  30
  31         float d = ((float)(b%1000)/1000.0);
  32
  33
  34         d = (d*2.0)-1.0;
  35
  36         return d;
  37 }
  38
  39 static float smooth_noise(int x, int z)
  40 {
  41         float sides;
  42         float centre;
  43
  44         sides = noise(x+1,z);
  45         sides += noise(x-1,z);
  46         sides += noise(x,z+1);
  47         sides += noise(x,z-1);
  48         sides /= 8.0;
  49
  50         centre = noise(x,z);
  51         centre /= 4.0;
  52
  53         return (sides+centre);
  54 }
  55
  56 static float interpolated_noise(int x, int z, float devisor)
  57 {
  58         float v1;
  59         float v2;
  60         float v3;
  61         float v4;
  62         float i1;
  63         float i2;
  64         float fx = (float)x/devisor;
  65         float fz = (float)z/devisor;
  66         int ix = fx;
  67         int iz = fz;
  68         if (x<1)
  69                 ix--;
  70         if (z<1)
  71                 iz--;
  72         fx -= ix;
  73         fz -= iz;
  74
  75         v1 = smooth_noise(ix,iz);
  76         v2 = smooth_noise(ix+1,iz);
  77         v3 = smooth_noise(ix,iz+1);
  78         v4 = smooth_noise(ix+1,iz+1);
  79
  80         i1 = (v1*(1.0-fx))+(v2*fx);
  81         i2 = (v3*(1.0-fx))+(v4*fx);
  82
  83         return (i1*(1.0-fz))+(i2*fz);
  84 }
  85
  86 void mapgen_seed(int s)
  87 {
  88         seed = s;
  89 }
  90
  91 float noise_height(int x, int z)
  92 {
  93         float n = interpolated_noise(x,z,60.0)*70.0;
  94
  95         n += interpolated_noise(x,z,20.0)*20.0;
  96         n += interpolated_noise(x,z,10.0)*4.0;
  97
  98         return n;
  99 }