/******************************************************************************/
/*
  Project   - MudBun
  Publisher - Long Bunny Labs
              http://LongBunnyLabs.com
  Author    - Ming-Lun "Allen" Chou
              http://AllenChou.net

  Based on project "webgl-noise" by Ashima Arts.
  Description : Array and textureless GLSL 2D simplex noise function.
      Author  : Ian McEwan, Ashima Arts.
  Maintainer  : ijm
      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
*/
/******************************************************************************/

#ifndef MUDBUN_CLASSIC_NOISE_2D
#define MUDBUN_CLASSIC_NOISE_2D

#include "NoiseCommon.cginc"

// classic Perlin noise
// single octave
float mbn_cnoise(float2 P)
{
  float4 Pi = floor(P.xyxy) + float4(0.0, 0.0, 1.0, 1.0);
  float4 Pf = frac (P.xyxy) - float4(0.0, 0.0, 1.0, 1.0);
  Pi = mbn_mod289(Pi); // To avoid truncation effects in permutation
  float4 ix = Pi.xzxz;
  float4 iy = Pi.yyww;
  float4 fx = Pf.xzxz;
  float4 fy = Pf.yyww;

  float4 i = mbn_permute(mbn_permute(ix) + iy);

  float4 gx = frac(i / 41.0) * 2.0 - 1.0 ;
  float4 gy = abs(gx) - 0.5 ;
  float4 tx = floor(gx + 0.5);
  gx = gx - tx;

  float2 g00 = float2(gx.x,gy.x);
  float2 g10 = float2(gx.y,gy.y);
  float2 g01 = float2(gx.z,gy.z);
  float2 g11 = float2(gx.w,gy.w);

  float4 norm = mbn_taylorInvSqrt(float4(dot(g00, g00), dot(g01, g01), dot(g10, g10), dot(g11, g11)));
  g00 *= norm.x;
  g01 *= norm.y;
  g10 *= norm.z;
  g11 *= norm.w;

  float n00 = dot(g00, float2(fx.x, fy.x));
  float n10 = dot(g10, float2(fx.y, fy.y));
  float n01 = dot(g01, float2(fx.z, fy.z));
  float n11 = dot(g11, float2(fx.w, fy.w));

  float2 fade_xy = mbn_fade(Pf.xy);
  float2 n_x = lerp(float2(n00, n01), float2(n10, n11), fade_xy.x);
  float n_xy = lerp(n_x.x, n_x.y, fade_xy.y);
  return 2.3 * n_xy;
}

// multiple octaves
DEFINE_NOISE_FUNC_MULTIPLE_OCTAVES(mbn_cnoise, float, float2, 0.5)

// classic Perlin noise, periodic variant
// single octave
float mbn_noise(float2 P, float2 rep)
{
  float4 Pi = floor(P.xyxy) + float4(0.0, 0.0, 1.0, 1.0);
  float4 Pf = frac (P.xyxy) - float4(0.0, 0.0, 1.0, 1.0);
  Pi = mbn_mod(Pi, rep.xyxy); // To create noise with explicit period
  Pi = mbn_mod289(Pi);        // To avoid truncation effects in permutation
  float4 ix = Pi.xzxz;
  float4 iy = Pi.yyww;
  float4 fx = Pf.xzxz;
  float4 fy = Pf.yyww;

  float4 i = mbn_permute(mbn_permute(ix) + iy);

  float4 gx = frac(i / 41.0) * 2.0 - 1.0 ;
  float4 gy = abs(gx) - 0.5 ;
  float4 tx = floor(gx + 0.5);
  gx = gx - tx;

  float2 g00 = float2(gx.x,gy.x);
  float2 g10 = float2(gx.y,gy.y);
  float2 g01 = float2(gx.z,gy.z);
  float2 g11 = float2(gx.w,gy.w);

  float4 norm = mbn_taylorInvSqrt(float4(dot(g00, g00), dot(g01, g01), dot(g10, g10), dot(g11, g11)));
  g00 *= norm.x;
  g01 *= norm.y;
  g10 *= norm.z;
  g11 *= norm.w;

  float n00 = dot(g00, float2(fx.x, fy.x));
  float n10 = dot(g10, float2(fx.y, fy.y));
  float n01 = dot(g01, float2(fx.z, fy.z));
  float n11 = dot(g11, float2(fx.w, fy.w));

  float2 fade_xy = mbn_fade(Pf.xy);
  float2 n_x = lerp(float2(n00, n01), float2(n10, n11), fade_xy.x);
  float n_xy = lerp(n_x.x, n_x.y, fade_xy.y);
  return 2.3 * n_xy;
}

// multiple octave
DEFINE_PERIODIC_NOISE_FUNC_MULTIPLE_OCTAVES(mbn_pnoise, float, float2)

#endif