public struct DDA {
        int n, ix;
        int[] start, end;
        int[] delta, step, counter;
        public int[] position;

        public DDA(int n, int[] start, int[] end) {
            this.n = n;
            if (start.Length != n || end.Length != n) {
                throw new ArgumentException();
            }
            this.start = start;
            this.end = end;
            position = new int[n];
            delta = new int[n];
            step = new int[n];
            counter = new int[n];
            ix = 0;
            Setup();
        }

        private void Setup() {
            for (int i = 0; i < n; i++) {
                position[i] = start[i];
                delta[i] = end[i] - start[i];
                step[i] = 0;

                if (delta[i] > 0) {
                    step[i] = 1;
                }

                if (delta[i] < 0) {
                    step[i] = -1;
                    delta[i] = -delta[i];
                }

                if (delta[ix] < delta[i]) {
                    ix = i;
                }
            }

            for (int i = 0; i < n; i++) {
                counter[i] = delta[ix];
            }
        }

        public bool Update() {
            for (int i = 0; i < n; i++) {
                counter[i] -= delta[i];
                if (counter[i] <= 0) {
                    counter[i] += delta[ix];
                    position[i] += step[i];
                }
            }
            return position[ix] != end[ix] + step[ix];
        }
    }

        public (Block, Box?) GetLookAtBlock(Vector3 pos, Vector3 look) {
            try {
                int[] start = new[] {
                    SandboxMath.RoundDown(pos.X),
                    SandboxMath.RoundDown(pos.Y),
                    SandboxMath.RoundDown(pos.Z)
                };

                look = look.Normalized() * 4;

                int[] end = new[] {
                    SandboxMath.RoundDown(pos.X + look.X),
                    SandboxMath.RoundDown(pos.Y + look.Y),
                    SandboxMath.RoundDown(pos.Z + look.Z)
                };

                DDA dda = new DDA(3, start, end);

                while (dda.Update()) {
                    Block block = GetBlock(dda.position[0], dda.position[1], dda.position[2]);
                    if (block != 0) {
                        return (
                            block,
                            new Box(
                                new Vector3(dda.position[0], dda.position[1], dda.position[2]),
                                new Vector3(dda.position[0] + 1, dda.position[1] + 1, dda.position[2] + 1)
                            )
                        );
                    }
                }
                return (0, null);
            } catch (IndexOutOfRangeException) {
                return (0, null);
            }
        }