The Maths behind Cabbiton's Ceiling

    public static void main(String[] args) {
        try {
            double num = Math.PI / 2.0 / 68.0;
            int[][] feelsgood = new int[69][69];
            for (int i = 0; i < 69; i++) {
                for (int j = 0; j < 69; j++) {
                    double dist = Math.sqrt(i * i + j * j);
                    int rnd = (int) Math.round(dist);
                    if (rnd <= 68) {
                        feelsgood[i][j] = (int) Math.round(20 * Math.sin(Math.PI * 0.5 + rnd * num));
                    } else {
                        feelsgood[i][j] = -1;
                    }
                }
            }
            String bigblock = String.format("%69s", "").replace(" ", "+--") + "+";
            for (int i = 0; i < 69; i++) {
                System.out.println(bigblock);
                for (int j = 0; j < 69; j++) {
                    if (i == j) {
                            System.out.print("|##");
                    } else if (feelsgood[i][j] != -1 && (i % 4 == 0 || j % 4 == 0)) {
                         if (feelsgood[i][j] % 2 == 1) {
                            System.out.print("|--");
                        } else {
                            System.out.printf("|%2d", feelsgood[i][j]);
                        }
                    } else {
                        System.out.print("|  ");
                    }
                }
                System.out.println("|");
            }
            System.out.println(bigblock);
        } catch (Exception e) {
        }
    }