mirror of https://git.code.sf.net/p/quake/newtree
85 lines
2.2 KiB
C
85 lines
2.2 KiB
C
/*
|
|
fractalnoise.c
|
|
|
|
LordHavocs fractal noise generator.
|
|
|
|
Copyright (C) 2000 Forest `LordHavoc` Hale.
|
|
|
|
This program is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU General Public License
|
|
as published by the Free Software Foundation; either version 2
|
|
of the License, or (at your option) any later version.
|
|
|
|
This program is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
|
|
|
|
See the GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with this program; if not, write to:
|
|
|
|
Free Software Foundation, Inc.
|
|
59 Temple Place - Suite 330
|
|
Boston, MA 02111-1307, USA
|
|
|
|
$Id$
|
|
*/
|
|
|
|
#include <stdlib.h>
|
|
|
|
void
|
|
fractalnoise (unsigned char *noise, int size)
|
|
{
|
|
int x, y, g, g2, amplitude, min, max, size1 = size - 1;
|
|
int *noisebuf;
|
|
|
|
#define n(x,y) noisebuf[((y)&size1)*size+((x)&size1)]
|
|
noisebuf = calloc (size * size, sizeof (int));
|
|
|
|
amplitude = 32767;
|
|
g2 = size;
|
|
n (0, 0) = 0;
|
|
for (; (g = g2 >> 1) >= 1; g2 >>= 1) {
|
|
// subdivide, diamond-square algorythm (really this has little to do
|
|
// with squares)
|
|
// diamond
|
|
for (y = 0; y < size; y += g2)
|
|
for (x = 0; x < size; x += g2)
|
|
n (x + g, y + g) =
|
|
(n (x, y) + n (x + g2, y) + n (x, y + g2) +
|
|
n (x + g2, y + g2)) >> 2;
|
|
// square
|
|
for (y = 0; y < size; y += g2)
|
|
for (x = 0; x < size; x += g2) {
|
|
n (x + g, y) =
|
|
(n (x, y) + n (x + g2, y) + n (x + g, y - g) +
|
|
n (x + g, y + g)) >> 2;
|
|
n (x, y + g) =
|
|
(n (x, y) + n (x, y + g2) + n (x - g, y + g) +
|
|
n (x + g, y + g)) >> 2;
|
|
}
|
|
// brownian motion theory
|
|
amplitude >>= 1;
|
|
for (y = 0; y < size; y += g)
|
|
for (x = 0; x < size; x += g)
|
|
n (x, y) += (rand () & amplitude);
|
|
}
|
|
// find range of noise values
|
|
min = max = 0;
|
|
for (y = 0; y < size; y++)
|
|
for (x = 0; x < size; x++) {
|
|
if (n (x, y) < min)
|
|
min = n (x, y);
|
|
if (n (x, y) > max)
|
|
max = n (x, y);
|
|
}
|
|
max -= min;
|
|
// normalize noise and copy to output
|
|
for (y = 0; y < size; y++)
|
|
for (x = 0; x < size; x++)
|
|
*noise++ = (n (x, y) - min) * 255 / max;
|
|
free (noisebuf);
|
|
#undef n
|
|
}
|