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** Copyright (C) 2014 NVIDIA Corporation.
** Copyright (C) 2017 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
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** This file is part of Qt 3D Studio.
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vec4 miNoise( in vec3 xyz )
{
  const float div = 1.0 / 256.0;

  ivec3 itmp = ivec3( xyz );
  ivec3 ixyz[3] = ivec3[]( itmp & 0xFF, itmp+1 & 0xFF, itmp+2 & 0xFF );
  vec3 fxyz = xyz - floor( xyz );

  vec3 dux, ux;
  dux.z = fxyz.x * div;
  dux.y = div - 2.0 * dux.z;
  dux.x = dux.z - div;
  ux.z = 0.5 * fxyz.x * dux.z;
  ux.y = dux.z + 0.5 * ( div - fxyz.x * dux.z );
  ux.x = ux.z - dux.z + 0.5 * div;

  vec3 duy, uy;
  duy.z = fxyz.y;
  duy.y = 1.0 - 2.0 * duy.z;
  duy.x = duy.z - 1.0;
  uy.z = 0.5 * square( duy.z );
  uy.y = duy.z + 0.5 - square( duy.z );
  uy.x = uy.z - duy.z + 0.5;

  float duz[3] = float[]( fxyz.z - 1.0, 1.0 - 2.0 * fxyz.z, fxyz.z );
  float uz[3]  = float[]( 0.5 * square( fxyz.z ) - fxyz.z + 0.5, fxyz.z + 0.5 - square( fxyz.z ), 0.5 * square( fxyz.z ) );

  int xx = random255X( ixyz[0].x );
  int yx = random255Y( ixyz[0].y );
  int zx = random255Z( ixyz[0].z );
  int xy = random255X( ixyz[1].x );
  int yy = random255Y( ixyz[1].y );
  int zy = random255Z( ixyz[1].z );

  int xxxy = xx ^ xy;
  int yxxy = yx ^ xy;
  int zxxy = zx ^ xy;
  int xxyy = xx ^ yy;
  int yxyy = yx ^ yy;
  int zxyy = zx ^ yy;
  int xxzy = xx ^ zy;
  int yxzy = yx ^ zy;
  int zxzy = zx ^ zy;

  int ixyzxx = ixyz[0].x ^ ixyz[1].x;
  int ixyzyx = ixyz[0].y ^ ixyz[1].x;
  int ixyzzx = ixyz[0].z ^ ixyz[1].x;
  int ixyzxy = ixyz[0].x ^ ixyz[1].y;
  int ixyzyy = ixyz[0].y ^ ixyz[1].y;
  int ixyzzy = ixyz[0].z ^ ixyz[1].y;
  int ixyzxz = ixyz[0].x ^ ixyz[1].z;
  int ixyzyz = ixyz[0].y ^ ixyz[1].z;
  int ixyzzz = ixyz[0].z ^ ixyz[1].z;


  vec4 ret = vec4( 0.0, 0.0, 0.0, 0.0 );

  for ( int i=0 ; i<3 ; i++ )
  {
    int iz = random255Z( ixyz[2][i] );

    mat3x3 nf = mat3x3( vec3( float( random255W( xxxy ^ iz ^ random255W( ixyzxx ^ ixyz[2][i] ) ) )
                            , float( random255W( yxxy ^ iz ^ random255W( ixyzyx ^ ixyz[2][i] ) ) )
                            , float( random255W( zxxy ^ iz ^ random255W( ixyzzx ^ ixyz[2][i] ) ) ) )
                      , vec3( float( random255W( xxyy ^ iz ^ random255W( ixyzxy ^ ixyz[2][i] ) ) )
                            , float( random255W( yxyy ^ iz ^ random255W( ixyzyy ^ ixyz[2][i] ) ) )
                            , float( random255W( zxyy ^ iz ^ random255W( ixyzzy ^ ixyz[2][i] ) ) ) )
                      , vec3( float( random255W( xxzy ^ iz ^ random255W( ixyzxz ^ ixyz[2][i] ) ) )
                            , float( random255W( yxzy ^ iz ^ random255W( ixyzyz ^ ixyz[2][i] ) ) )
                            , float( random255W( zxzy ^ iz ^ random255W( ixyzzz ^ ixyz[2][i] ) ) ) ) );

    float fxdz = dot( uy, dux * nf );
    vec3 dy = ux * nf;
    float dz = dot( uy, dy );

    ret.x += uz[i] * fxdz;
    ret.y += uz[i] * dot( duy, dy );
    ret.z += duz[i] * dz;
    ret.w += uz[i] * dz;
  }
  return( ret );
}