/// <summary> /// See the documentation on the base class. /// <seealso cref="Module"/> /// </summary> /// <param name="x">X coordinate</param> /// <param name="y">Y coordinate</param> /// <param name="z">Z coordinate</param> /// <returns>Returns the computed value</returns> public override double GetValue(double x, double y, double z) { var ix = NoiseMath.FastFloor(x); var iy = NoiseMath.FastFloor(y); var iz = NoiseMath.FastFloor(z); return(((ix & 1) ^ (iy & 1) ^ (iz & 1)) != 0 ? -1.0 : 1.0); }
// 3D simplex noise public static double SimplexNoise3D(double xin, double yin, double zin) { // Skew the input space to determine which simplex cell we're in // Very nice and simple skew factor for 3D double s = (xin + yin + zin) * F3; int i = NoiseMath.FastFloor(xin + s); int j = NoiseMath.FastFloor(yin + s); int k = NoiseMath.FastFloor(zin + s); double t = (i + j + k) * G3; // Unskew the cell origin back to (x,y,z) space double X0 = i - t; double Y0 = j - t; double Z0 = k - t; // The x,y,z distances from the cell origin double x0 = xin - X0; double y0 = yin - Y0; double z0 = zin - Z0; // For the 3D case, the simplex shape is a slightly irregular tetrahedron. // Determine which simplex we are in. int i1, j1, k1; // Offsets for second corner of simplex in (i,j,k) coords int i2, j2, k2; // Offsets for third corner of simplex in (i,j,k) coords if (x0 >= y0) { // X Y Z order if (y0 >= z0) { i1 = 1; j1 = 0; k1 = 0; i2 = 1; j2 = 1; k2 = 0; } // X Z Y order else if (x0 >= z0) { i1 = 1; j1 = 0; k1 = 0; i2 = 1; j2 = 0; k2 = 1; } // Z X Y order else { i1 = 0; j1 = 0; k1 = 1; i2 = 1; j2 = 0; k2 = 1; } } else // x0<y0 { // Z Y X order if (y0 < z0) { i1 = 0; j1 = 0; k1 = 1; i2 = 0; j2 = 1; k2 = 1; } // Y Z X order else if (x0 < z0) { i1 = 0; j1 = 1; k1 = 0; i2 = 0; j2 = 1; k2 = 1; } // Y X Z order else { i1 = 0; j1 = 1; k1 = 0; i2 = 1; j2 = 1; k2 = 0; } } // 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. double x1 = x0 - i1 + G3; // Offsets for second corner in (x,y,z) coords double y1 = y0 - j1 + G3; double z1 = z0 - k1 + G3; double x2 = x0 - i2 + 2.0 * G3; // Offsets for third corner in (x,y,z) coords double y2 = y0 - j2 + 2.0 * G3; double z2 = z0 - k2 + 2.0 * G3; double x3 = x0 - 1.0 + 3.0 * G3; // Offsets for last corner in (x,y,z) coords double y3 = y0 - 1.0 + 3.0 * G3; double z3 = z0 - 1.0 + 3.0 * G3; // Work out the hashed gradient indices of the four simplex corners int ii = i & 255; int jj = j & 255; int kk = k & 255; int gi0 = PermMod12[ii + Perm[jj + Perm[kk]]]; int gi1 = PermMod12[ii + i1 + Perm[jj + j1 + Perm[kk + k1]]]; int gi2 = PermMod12[ii + i2 + Perm[jj + j2 + Perm[kk + k2]]]; int gi3 = PermMod12[ii + 1 + Perm[jj + 1 + Perm[kk + 1]]]; // Noise contributions from the four corners double n0 = 0.0, n1 = 0.0, n2 = 0.0, n3 = 0.0; // Calculate the contribution from the four corners double t0 = 0.6 - x0 * x0 - y0 * y0 - z0 * z0; if (t0 >= 0) { t0 *= t0; n0 = t0 * t0 * Dot(ref Grad3[gi0], x0, y0, z0); } double t1 = 0.6 - x1 * x1 - y1 * y1 - z1 * z1; if (t1 >= 0) { t1 *= t1; n1 = t1 * t1 * Dot(ref Grad3[gi1], x1, y1, z1); } double t2 = 0.6 - x2 * x2 - y2 * y2 - z2 * z2; if (t2 >= 0) { t2 *= t2; n2 = t2 * t2 * Dot(ref Grad3[gi2], x2, y2, z2); } double t3 = 0.6 - x3 * x3 - y3 * y3 - z3 * z3; if (t3 >= 0) { t3 *= t3; n3 = t3 * t3 * Dot(ref 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)); }