/*
Smooth 3D pseudorandom noise generation.

Orion Sky Lawlor, olawlor@acm.org, 2005/12/14
*/
#include "osl/perlin_noise.h"
#include <math.h>

/*
From the 
 JAVA REFERENCE IMPLEMENTATION OF IMPROVED NOISE - COPYRIGHT 2002 KEN PERLIN.
  Translated to C++ and hacked by Orion Lawlor, 2005/12/13
*/
static unsigned char *make_permutation(void) 
{
	const static unsigned char permutation[256] = { 151,160,137,91,90,15,
	131,13,201,95,96,53,194,233,7,225,140,36,103,30,69,142,8,99,37,240,21,10,23,
	190, 6,148,247,120,234,75,0,26,197,62,94,252,219,203,117,35,11,32,57,177,33,
	88,237,149,56,87,174,20,125,136,171,168, 68,175,74,165,71,134,139,48,27,166,
	77,146,158,231,83,111,229,122,60,211,133,230,220,105,92,41,55,46,245,40,244,
	102,143,54, 65,25,63,161, 1,216,80,73,209,76,132,187,208, 89,18,169,200,196,
	135,130,116,188,159,86,164,100,109,198,173,186, 3,64,52,217,226,250,124,123,
	5,202,38,147,118,126,255,82,85,212,207,206,59,227,47,16,58,17,182,189,28,42,
	223,183,170,213,119,248,152, 2,44,154,163, 70,221,153,101,155,167, 43,172,9,
	129,22,39,253, 19,98,108,110,79,113,224,232,178,185, 112,104,218,246,97,228,
	251,34,242,193,238,210,144,12,191,179,162,241, 81,51,145,235,249,14,239,107,
	49,192,214, 31,181,199,106,157,184, 84,204,176,115,121,50,45,127, 4,150,254,
	138,236,205,93,222,114,67,29,24,72,243,141,128,195,78,66,215,61,156,180
	};
	unsigned char *p=new unsigned char[512];
	for (int i=0; i < 256 ; i++) 
		p[256+i] = p[i] = permutation[i]; 
	return p;
}

double osl::PerlinNoise::noise(double x, double y, double z)
{
	static unsigned char *p=make_permutation();
	int ix=(int)floor(x), iy=(int)floor(y), iz=(int)floor(z);
	int X = ix & 255,		      // FIND UNIT CUBE THAT
	    Y = iy & 255,		      // CONTAINS POINT.
	    Z = iz & 255;
	x -= ix;  			      // FIND RELATIVE X,Y,Z
	y -= iy;  			      // OF POINT IN CUBE.
	z -= iz;
	double u = fade(x),				   // COMPUTE FADE CURVES
	       v = fade(y),				   // FOR EACH OF X,Y,Z.
	       w = fade(z);
	int A = p[X  ]+Y, AA = p[A]+Z, AB = p[A+1]+Z,	// HASH COORDINATES OF
	    B = p[X+1]+Y, BA = p[B]+Z, BB = p[B+1]+Z;	// THE 8 CUBE CORNERS,

	return lerp(w, lerp(v, lerp(u, grad(p[AA  ], x  , y  , z   ),  // AND ADD
				       grad(p[BA  ], x-1, y  , z   )), // BLENDED
			       lerp(u, grad(p[AB  ], x  , y-1, z   ),  // RESULTS
				       grad(p[BB  ], x-1, y-1, z   ))),// FROM  8
		       lerp(v, lerp(u, grad(p[AA+1], x  , y  , z-1 ),  // CORNERS
				       grad(p[BA+1], x-1, y  , z-1 )), // OF CUBE
			       lerp(u, grad(p[AB+1], x  , y-1, z-1 ),
				       grad(p[BB+1], x-1, y-1, z-1 ))));
}