#ifndef __NOISE_3D__
#define __NOISE_3D__

#include "noiseMath.cginc"

//
// Description : Array and textureless GLSL 2D/3D/4D simplex 
//               noise functions.
//      Author : Ian McEwan, Ashima Arts.
//  Maintainer : stegu
//     Lastmod : 20110822 (ijm)
//     License : Copyright (C) 2011 Ashima Arts. All rights reserved.
//               Distributed under the MIT License. See LICENSE file.
//               https://github.com/ashima/webgl-noise
//               https://github.com/stegu/webgl-noise
// 

float snoise(float3 v)
{ 
	const float2 C = float2(1.0/6.0, 1.0/3.0) ;
	const float4 D = float4(0.0, 0.5, 1.0, 2.0);

	// First corner
	float3 i  = floor(v + dot(v, C.yyy) );
	float3 x0 =   v - i + dot(i, C.xxx) ;

	// Other corners
	float3 g = step(x0.yzx, x0.xyz);
	float3 l = 1.0 - g;
	float3 i1 = min( g.xyz, l.zxy );
	float3 i2 = max( g.xyz, l.zxy );

	//   x0 = x0 - 0.0 + 0.0 * C.xxx;
	//   x1 = x0 - i1  + 1.0 * C.xxx;
	//   x2 = x0 - i2  + 2.0 * C.xxx;
	//   x3 = x0 - 1.0 + 3.0 * C.xxx;
	float3 x1 = x0 - i1 + C.xxx;
	float3 x2 = x0 - i2 + C.yyy; // 2.0*C.x = 1/3 = C.y
	float3 x3 = x0 - D.yyy;      // -1.0+3.0*C.x = -0.5 = -D.y

	// Permutations
	i = mod289(i); 
	float4 p = permute( permute( permute( 
	           i.z + float4(0.0, i1.z, i2.z, 1.0 ))
	         + i.y + float4(0.0, i1.y, i2.y, 1.0 )) 
	         + i.x + float4(0.0, i1.x, i2.x, 1.0 ));

	// Gradients: 7x7 points over a square, mapped onto an octahedron.
	// The ring size 17*17 = 289 is close to a multiple of 49 (49*6 = 294)
	float n_ = 0.142857142857; // 1.0/7.0
	float3  ns = n_ * D.wyz - D.xzx;
	
	float4 j = p - 49.0 * floor(p * ns.z * ns.z);  //  mod(p,7*7)
	
	float4 x_ = floor(j * ns.z);
	float4 y_ = floor(j - 7.0 * x_ );    // mod(j,N)
	
	float4 x = x_ *ns.x + ns.yyyy;
	float4 y = y_ *ns.x + ns.yyyy;
	float4 h = 1.0 - abs(x) - abs(y);
	
	float4 b0 = float4( x.xy, y.xy );
	float4 b1 = float4( x.zw, y.zw );
	
	//float4 s0 = float4(lessThan(b0,0.0))*2.0 - 1.0;
	//float4 s1 = float4(lessThan(b1,0.0))*2.0 - 1.0;
	float4 s0 = floor(b0)*2.0 + 1.0;
	float4 s1 = floor(b1)*2.0 + 1.0;
	float4 sh = -step(h, float4(0.0));
	
	float4 a0 = b0.xzyw + s0.xzyw*sh.xxyy ;
	float4 a1 = b1.xzyw + s1.xzyw*sh.zzww ;
	
	float3 p0 = float3(a0.xy,h.x);
	float3 p1 = float3(a0.zw,h.y);
	float3 p2 = float3(a1.xy,h.z);
	float3 p3 = float3(a1.zw,h.w);

	//Normalise gradients
	float4 norm = taylorInvSqrt(float4(dot(p0,p0), dot(p1,p1), dot(p2, p2), dot(p3,p3)));
	p0 *= norm.x;
	p1 *= norm.y;
	p2 *= norm.z;
	p3 *= norm.w;

	// Mix final noise value
	float4 m = max(0.6 - float4(dot(x0,x0), dot(x1,x1), dot(x2,x2), dot(x3,x3)), 0.0);
	m = m * m;
	return 42.0 * dot( m*m, float4( dot(p0,x0), dot(p1,x1), 
				  dot(p2,x2), dot(p3,x3) ) );
}

#endif