perlin.c

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/*
* libtcod 1.3.1
* Copyright (c) 2007,2008 J.C.Wilk
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*     * Redistributions of source code must retain the above copyright
*       notice, this list of conditions and the following disclaimer.
*     * Redistributions in binary form must reproduce the above copyright
*       notice, this list of conditions and the following disclaimer in the
*       documentation and/or other materials provided with the distribution.
*     * The name of J.C.Wilk may not be used to endorse or promote products
*       derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY J.C.WILK ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL J.C.WILK BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
 
#include <math.h>
#include <stdlib.h>
#include "SDL.h"
#include "SDL_thread.h"
 
#include "naev.h"
#include "perlin.h"
 
#include "log.h"
#include "nfile.h"
#include "nstring.h"
#include "rng.h"
 
#define SIMPLEX_SCALE 0.5f
 
struct perlin_data_s {
   int ndim; 
   unsigned char map[256]; 
};
 
#define SWAP(a, b, t)      (t) = (a); (a) = (b); (b) = (t) 
#define FLOOR(a)           ((int)(a) - ((a) < 0 && (a) != (int)(a))) 
perlin_data_t* noise_new (void)
{
   perlin_data_t *pdata;
   int i, j;
   unsigned char tmp;
 
   /* Create the data. */
   pdata = calloc(sizeof(perlin_data_t),1);
 
   /* Create the buffer and map. */
   for (i=0; i<256; i++)
      pdata->map[i] = (unsigned char)i;
 
   while (--i) {
      j = RNG(0, 255);
      SWAP(pdata->map[i], pdata->map[j], tmp);
   }
 
   return pdata;
}
 
#define NOISE_SIMPLEX_GRADIENT_1D(n,h,x) { float grad; h &= 0xF; grad=1.0f+(h & 7); if ( h & 8 ) grad = -grad; n = grad * x; }
 
float noise_simplex1( perlin_data_t* pdata, float f[1] )
{
   int i0   = (int)FLOOR( f[0]*SIMPLEX_SCALE );
   int i1   = i0+1;
   float x0 = f[0]*SIMPLEX_SCALE - i0;
   float x1 = x0 - 1.0f;
   float t0 = 1.0f - x0*x0;
   float t1 = 1.0f - x1*x1;
   float n0,n1;
 
   t0    = t0*t0;
   t1    = t1*t1;
   i0    = pdata->map[i0&0xFF];
   NOISE_SIMPLEX_GRADIENT_1D( n0, i0, x0 );
   n0   *= t0*t0;
   i1    = pdata->map[i1&0xFF];
   NOISE_SIMPLEX_GRADIENT_1D( n1, i1, x1 );
   n1   *= t1*t1;
 
   return 0.25f * (n0+n1);
}
 
void noise_delete( perlin_data_t* pdata )
{
   free(pdata);
}