//    SimplexPerlinNoiseマップ作成シェーダ
//        ver 1.0 2020/06/07
//        by yarunashi@dooon

// 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
// 

vec3 mod289(vec3 x) {
  return x - floor(x * (1.0 / 289.0)) * 289.0;
}

vec4 mod289(vec4 x) {
  return x - floor(x * (1.0 / 289.0)) * 289.0;
}

vec4 permute(vec4 x) {
     return mod289(((x*34.0)+1.0)*x);
}

vec4 taylorInvSqrt(vec4 r)
{
  return 1.79284291400159 - 0.85373472095314 * r;
}

float snoise(vec3 v)
  { 
  const vec2  C = vec2(1.0/6.0, 1.0/3.0) ;
  const vec4  D = vec4(0.0, 0.5, 1.0, 2.0);

// First corner
  vec3 i  = floor(v + dot(v, C.yyy) );
  vec3 x0 =   v - i + dot(i, C.xxx) ;

// Other corners
  vec3 g = step(x0.yzx, x0.xyz);
  vec3 l = 1.0 - g;
  vec3 i1 = min( g.xyz, l.zxy );
  vec3 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;
  vec3 x1 = x0 - i1 + C.xxx;
  vec3 x2 = x0 - i2 + C.yyy; // 2.0*C.x = 1/3 = C.y
  vec3 x3 = x0 - D.yyy;      // -1.0+3.0*C.x = -0.5 = -D.y

// Permutations
  i = mod289(i); 
  vec4 p = permute( permute( permute( 
             i.z + vec4(0.0, i1.z, i2.z, 1.0 ))
           + i.y + vec4(0.0, i1.y, i2.y, 1.0 )) 
           + i.x + vec4(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
  vec3  ns = n_ * D.wyz - D.xzx;

  vec4 j = p - 49.0 * floor(p * ns.z * ns.z);  //  mod(p,7*7)

  vec4 x_ = floor(j * ns.z);
  vec4 y_ = floor(j - 7.0 * x_ );    // mod(j,N)

  vec4 x = x_ *ns.x + ns.yyyy;
  vec4 y = y_ *ns.x + ns.yyyy;
  vec4 h = 1.0 - abs(x) - abs(y);

  vec4 b0 = vec4( x.xy, y.xy );
  vec4 b1 = vec4( x.zw, y.zw );

  //vec4 s0 = vec4(lessThan(b0,0.0))*2.0 - 1.0;
  //vec4 s1 = vec4(lessThan(b1,0.0))*2.0 - 1.0;
  vec4 s0 = floor(b0)*2.0 + 1.0;
  vec4 s1 = floor(b1)*2.0 + 1.0;
  vec4 sh = -step(h, vec4(0.0));

  vec4 a0 = b0.xzyw + s0.xzyw*sh.xxyy ;
  vec4 a1 = b1.xzyw + s1.xzyw*sh.zzww ;

  vec3 p0 = vec3(a0.xy,h.x);
  vec3 p1 = vec3(a0.zw,h.y);
  vec3 p2 = vec3(a1.xy,h.z);
  vec3 p3 = vec3(a1.zw,h.w);

//Normalise gradients
  vec4 norm = taylorInvSqrt(vec4(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
  vec4 m = max(0.6 - vec4(dot(x0,x0), dot(x1,x1), dot(x2,x2), dot(x3,x3)), 0.0);
  m = m * m;
  return 42.0 * dot( m*m, vec4( dot(p0,x0), dot(p1,x1), 
                                dot(p2,x2), dot(p3,x3) ) );
}


// xs_begin
// author : 'yarunashi@dooon'
// arg : { id = '0' name = 'xscale' value = '2' range = '0.0 100.0' step = '0.5'		decimal = '1' }
// arg : { id = '1' name = 'yscale' value = '2' range = '0.0 100.0' step = '0.5'		decimal = '1' }
// arg : { id = '2' name = 'seed' value = '0' range = '0.0 100.0' step = '0.1' decimal = '1' }
// arg : { id = '3' name = 'numcolors' value = '255' range = '1 255' step = '1' decimal = '0' }
// arg : { id = '4' name = 'seamless' value = '0' range = '0 1' step = '1' decimal = '0' }
// arg : { id = '5' name = 'fbm' value = '0' range = '0 1' step = '1' decimal = '0' }
// arg : { id = '6' name = 'hscale' value = '1.0' range = '0.1 100.0' step = '0.1'		decimal = '1' }
// arg : { id = '7' name = 'thickness' value = '1' range = '1 255' step = '1' decimal = '0' }
// xs_end

float xscale = (i_args[0] == 0) ? 2.0 : iArgs[0] ; 
float yscale = (i_args[1] == 0) ? 2.0 : iArgs[1] ; 
float seed = (i_args[2] == 0) ? 0.0 : iArgs[2] ;
float step = (i_args[3] == 0) ? 255.0 : iArgs[3] ;
float seamless = (i_args[4] == 0) ? 0.0 : 1.0;
float fbm = (i_args[5] == 0) ? 0.0 : 1.0;
float hscale = (iArgs[6] == 0) ? 1.0 : iArgs[6] ; 
float thickness = (iArgs[7] == 0) ? 1.0 : iArgs[7] ; 


// シームありノイズ生成
float smnoise(vec2 v)
{
    vec3 p = vec3(v.x * xscale / i_volume_size.x, v.y * yscale / i_volume_size.y, seed);
    float r = snoise(p);
    return (r + 1.0) / 2.0; //0.0~1.0
}

//フラクショナルブラウン運動
#define NUM_OCTAVES 5
float fsmnoise(vec2 x) {
	float v = 0.0;
	float a = 0.5;
	vec2 shift = vec2(100);
	// Rotate to reduce axial bias
    mat2 rot = mat2(cos(0.5), sin(0.5), -sin(0.5), cos(0.50));
	for (int i = 0; i < NUM_OCTAVES; ++i) {
		v += a * smnoise(x);
		x = rot * x * 2.0 + shift;
		a *= 0.5;
	}
	return v;
}


// シームレスノイズ生成
float smlessnoise(vec2 v){
	vec2 p = mod(v, i_volume_size.xy);
    vec2 q = p / i_volume_size.xy;
    vec2 r = i_volume_size.xy;
    return smnoise(vec2(p.x,       p.y      )) *        q.x  *        q.y  +
           smnoise(vec2(p.x,       p.y + r.y)) *        q.x  * (1.0 - q.y) +
           smnoise(vec2(p.x + r.x, p.y      )) * (1.0 - q.x) *        q.y  +
           smnoise(vec2(p.x + r.x, p.y + r.y)) * (1.0 - q.x) * (1.0 - q.y);
}

float fsmlessnoise(vec2 v){
	vec2 p = mod(v, i_volume_size.xy);
    vec2 q = p / i_volume_size.xy;
    vec2 r = i_volume_size.xy;
    return fsmnoise(vec2(p.x,       p.y      )) *        q.x  *        q.y  +
           fsmnoise(vec2(p.x,       p.y + r.y)) *        q.x  * (1.0 - q.y) +
           fsmnoise(vec2(p.x + r.x, p.y      )) * (1.0 - q.x) *        q.y  +
           fsmnoise(vec2(p.x + r.x, p.y + r.y)) * (1.0 - q.x) * (1.0 - q.y);
}

float makemap(vec3 v) {  
    float r = 0.0;
    if (seamless >= 1.0) {
        // seamless noise
        if (fbm >= 1.0) {
            r = fsmlessnoise(v.xy);
        } else {
            r = smlessnoise(v.xy);
        }
    } else {
        if (fbm >= 1.0) {
            r = fsmnoise(v.xy);
        } else {
            r = smnoise(v.xy);
        }
    }
    r = r * 255;
    return r - mod(r, 255.0 / step) + 1;
}

float map(vec3 v) {  

	//マップの色1-255を取得
	float index = makemap(v);

	//色の高さを反転
	float height = 256.0 - index;

	//空間の高さに合わせる
	height = (height / 255.0) * i_volume_size.z * hscale;

    if (i_volume_size.z > 1.0) {
        //色の幅を調整
        index = 256.0 - height;
        index = index - mod(index, thickness) + 1;
    }

    return ( floor(v.z) < height ? index : 0.0 );
}