/*
 * noise.cc: noise generators
 *
 * This file is part of Pyrit Ray Tracer.
 *
 * Copyright 2006, 2008  Radek Brich
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include <math.h>

#include "noise.h"

/*
Perlin noise
Based on JAVA REFERENCE IMPLEMENTATION OF IMPROVED NOISE by KEN PERLIN (COPYRIGHT 2002)
*/

Float fade(Float t)
{
	return t * t * t * (t * (t * 6 - 15) + 10);
}

Float lerp(Float t, Float a, Float b)
{
	return a + t * (b - a);
}

Float grad(unsigned char hash, Float x, Float y, Float z)
{
	unsigned char h = hash & 15;            // CONVERT LO 4 BITS OF HASH CODE
	Float	u = h<8 ? x : y,                 // INTO 12 GRADIENT DIRECTIONS.
			v = h<4 ? y : h==12||h==14 ? x : z;
	return ((h&1) == 0 ? u : -u) + ((h&2) == 0 ? v : -v);
}

const unsigned char p[512] =
{
	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,

	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
};


Float perlin(Float x, Float y, Float z)
{
	int	X = (int)floor(x) & 255,
		Y = (int)floor(y) & 255,
		Z = (int)floor(z) & 255;
	x -= floor(x);
	y -= floor(y);
	z -= floor(z);
	Float	u = fade(x),
			v = fade(y),
			w = fade(z);
	int	A = p[X  ]+Y, AA = p[A]+Z, AB = p[A+1]+Z,
		B = p[X+1]+Y, BA = p[B]+Z, BB = p[B+1]+Z;

	return	lerp(w, lerp(v, lerp(u, grad(p[AA  ], x  , y  , z   ),
									grad(p[BA  ], x-1, y  , z   )),
							lerp(u, grad(p[AB  ], x  , y-1, z   ),
									grad(p[BB  ], x-1, y-1, z   ))),
					lerp(v, lerp(u, grad(p[AA+1], x  , y  , z-1 ),
									grad(p[BA+1], x-1, y  , z-1 )),
							lerp(u, grad(p[AB+1], x  , y-1, z-1 ),
									grad(p[BB+1], x-1, y-1, z-1 ))));
}