Azmyth.Numbers.grad C# (CSharp) Method

        public static double grad(int hash, double x, double y, double z)
        {
            switch (hash & 0xF)
            {
                case 0x0: return x + y;
                case 0x1: return -x + y;
                case 0x2: return x - y;
                case 0x3: return -x - y;
                case 0x4: return x + z;
                case 0x5: return -x + z;
                case 0x6: return x - z;
                case 0x7: return -x - z;
                case 0x8: return y + z;
                case 0x9: return -y + z;
                case 0xA: return y - z;
                case 0xB: return -y - z;
                case 0xC: return y + x;
                case 0xD: return -y + z;
                case 0xE: return y - x;
                case 0xF: return -y - z;
                default: return 0; // never happens
            }
        }