noise3d( xin, yin, zin ) {

		let n0; // Noise contributions from the four corners
		let n1;
		let n2;
		let n3;
		// Skew the input space to determine which simplex cell we're in
		const F3 = 1.0 / 3.0;
		const s = ( xin + yin + zin ) * F3; // Very nice and simple skew factor for 3D
		const i = Math.floor( xin + s );
		const j = Math.floor( yin + s );
		const k = Math.floor( zin + s );
		const G3 = 1.0 / 6.0; // Very nice and simple unskew factor, too
		const t = ( i + j + k ) * G3;
		const X0 = i - t; // Unskew the cell origin back to (x,y,z) space
		const Y0 = j - t;
		const Z0 = k - t;
		const x0 = xin - X0; // The x,y,z distances from the cell origin
		const y0 = yin - Y0;
		const z0 = zin - Z0;

		// For the 3D case, the simplex shape is a slightly irregular tetrahedron.
		// Determine which simplex we are in.
		let i1; // Offsets for second corner of simplex in (i,j,k) coords

		let j1;
		let k1;
		let i2; // Offsets for third corner of simplex in (i,j,k) coords
		let j2;
		let k2;
		if ( x0 >= y0 ) {

			if ( y0 >= z0 ) {

				i1 = 1; j1 = 0; k1 = 0; i2 = 1; j2 = 1; k2 = 0;

				// X Y Z order

			} else if ( x0 >= z0 ) {

				i1 = 1; j1 = 0; k1 = 0; i2 = 1; j2 = 0; k2 = 1;

				// X Z Y order

			} else {

				i1 = 0; j1 = 0; k1 = 1; i2 = 1; j2 = 0; k2 = 1;

			} // Z X Y order

		} else { // x0<y0

			if ( y0 < z0 ) {

				i1 = 0; j1 = 0; k1 = 1; i2 = 0; j2 = 1; k2 = 1;

				// Z Y X order

			} else if ( x0 < z0 ) {

				i1 = 0; j1 = 1; k1 = 0; i2 = 0; j2 = 1; k2 = 1;

				// Y Z X order

			} else {

				i1 = 0; j1 = 1; k1 = 0; i2 = 1; j2 = 1; k2 = 0;

			} // Y X Z order

		}

		// A step of (1,0,0) in (i,j,k) means a step of (1-c,-c,-c) in (x,y,z),
		// a step of (0,1,0) in (i,j,k) means a step of (-c,1-c,-c) in (x,y,z), and
		// a step of (0,0,1) in (i,j,k) means a step of (-c,-c,1-c) in (x,y,z), where
		// c = 1/6.
		const x1 = x0 - i1 + G3; // Offsets for second corner in (x,y,z) coords
		const y1 = y0 - j1 + G3;
		const z1 = z0 - k1 + G3;
		const x2 = x0 - i2 + 2.0 * G3; // Offsets for third corner in (x,y,z) coords
		const y2 = y0 - j2 + 2.0 * G3;
		const z2 = z0 - k2 + 2.0 * G3;
		const x3 = x0 - 1.0 + 3.0 * G3; // Offsets for last corner in (x,y,z) coords
		const y3 = y0 - 1.0 + 3.0 * G3;
		const z3 = z0 - 1.0 + 3.0 * G3;
		// Work out the hashed gradient indices of the four simplex corners
		const ii = i & 255;
		const jj = j & 255;
		const kk = k & 255;
		const gi0 = this.perm[ ii + this.perm[ jj + this.perm[ kk ] ] ] % 12;
		const gi1 = this.perm[ ii + i1 + this.perm[ jj + j1 + this.perm[ kk + k1 ] ] ] % 12;
		const gi2 = this.perm[ ii + i2 + this.perm[ jj + j2 + this.perm[ kk + k2 ] ] ] % 12;
		const gi3 = this.perm[ ii + 1 + this.perm[ jj + 1 + this.perm[ kk + 1 ] ] ] % 12;
		// Calculate the contribution from the four corners
		let t0 = 0.6 - x0 * x0 - y0 * y0 - z0 * z0;
		if ( t0 < 0 ) n0 = 0.0;
		else {

			t0 *= t0;
			n0 = t0 * t0 * this._dot3( this.grad3[ gi0 ], x0, y0, z0 );

		}

		let t1 = 0.6 - x1 * x1 - y1 * y1 - z1 * z1;
		if ( t1 < 0 ) n1 = 0.0;
		else {

			t1 *= t1;
			n1 = t1 * t1 * this._dot3( this.grad3[ gi1 ], x1, y1, z1 );

		}

		let t2 = 0.6 - x2 * x2 - y2 * y2 - z2 * z2;
		if ( t2 < 0 ) n2 = 0.0;
		else {

			t2 *= t2;
			n2 = t2 * t2 * this._dot3( this.grad3[ gi2 ], x2, y2, z2 );

		}

		let t3 = 0.6 - x3 * x3 - y3 * y3 - z3 * z3;
		if ( t3 < 0 ) n3 = 0.0;
		else {

			t3 *= t3;
			n3 = t3 * t3 * this._dot3( this.grad3[ gi3 ], x3, y3, z3 );

		}

		// Add contributions from each corner to get the final noise value.
		// The result is scaled to stay just inside [-1,1]
		return 32.0 * ( n0 + n1 + n2 + n3 );

	}
A 3D simplex noise method.

@param {number} xin - The x coordinate.
@param {number} yin - The y coordinate.
@param {number} zin - The z coordinate.
@return {number} The noise value.