#/***********************************************************
#    dragon2.rb -- ドラゴンカーブ
#***********************************************************/
require "plotter.rb"

ORDER = 10
RIGHT = 0; LEFT = 1

fold = Array.new(ORDER).fill(0)
fold[ORDER-1] = 1

gr_on
move(200, 140)
dx = 0;  dy = 2;  draw_rel(3 * dx, 3 * dy);  p = 0
for k in 1..ORDER
    fold[p] = LEFT;  q = 2 * p
    for i in p..q
        case fold[q - i] 
        when RIGHT:
            fold[i] = LEFT;  dx1 = -dy;  dy1 = dx
        when LEFT:
            fold[i] = RIGHT;  dx1 = dy;  dy1 = -dx
        end
        draw_rel(dx + dx1, dy + dy1)
        draw_rel(3 * dx1, 3 * dy1)
        dx = dx1;  dy = dy1
    end
    p = q + 1
end
gr_off

exit 0