#/***********************************************************
#    ifs.c -- フラクタルによる画像圧縮
#***********************************************************/
require "window.rb"

# シダ(fern)のデータ 
left = -5
bottom = 0
right = 5
top = 10
       a = [ 0   ,  0.85,  0.2 , -0.15 ]
       b = [ 0   ,  0.04, -0.26,  0.28 ]
       c = [ 0   , -0.04,  0.23,  0.26 ]
       d = [ 0.16,  0.85,  0.22,  0.24 ]
       e = [ 0   ,  0   ,  0   ,  0    ]
       f = [ 0   ,  1.6 ,  1.6 ,  0.44 ]

N = a.size
M = 25 * N

ip = Array.new(N).fill(0)
tbl = []

p = []

# 確率の計算 
s = 0.0
for i in 0...N
    p[i] = (a[i] * d[i] - b[i] * c[i]).abs
    s += p[i];  ip[i] = i
end
# 整列 
for i in 0...N
    k = i
    for j in i...N
        if (p[j] < p[k]); k = j; end
    end
    t = p[i];  p[i] = p[k];  p[k] = t
    r = ip[i];  ip[i] = ip[k];  ip[k] = r
end
# 表作成 
r = M
for i in 0...N
    k = (r * p[i] / s + 0.5).to_i;  s -= p[i]
    begin
       tbl[r -= 1] = ip[i]
    end while ((k -= 1) > 0)
end
# IFSのアトラクタをプロット 
gr_on; gr_window(left, bottom, right, top, 1, 0)
gr_plot_start
x = y = 0
for i in 0...30000
    print "\r", i
    k = (M * rand).to_i
    j = tbl[k]
    t = a[j] * x + b[j] * y + e[j]
    y = c[j] * x + d[j] * y + f[j]
    x = t
    if (i >= 10); $gplot.puts "#{x} #{y}"; end
end
print "\n"
gr_plot_end
gr_off

exit 0

#if 0  *************************************************
=begin
# Sierpinskiの三角形のデータ 
left = 0
bottom = 0
right = 1
top = 1

   a = [ 0.5 , 0.5 , 0.5  ]
   b = [ 0   , 0   , 0    ]
   c = [ 0   , 0   , 0    ]
   d = [ 0.5 , 0.5 , 0.5  ]
   e = [ 0   , 1   , 0.5  ]
   f = [ 0   , 0   , 0.5  ]

# 木のデータ 
bottom = 0
right = 1
top = 1

   a = [  0   ,  0.1 ,  0.42,  0.42 ]
   b = [  0   ,  0   , -0.42,  0.42 ]
   c = [  0   ,  0   ,  0.42, -0.42 ]
   d = [  0.5 ,  0.1 ,  0.42,  0.42 ]
   e = [  0   ,  0   ,  0   ,  0    ]
   f = [  0   ,  0.2 ,  0.2 ,  0.2  ]

# もっと現実的な木のデータ 
bottom = 0
right = 1
top = 2

   a = [  0.05,  0.05,  0.46,  0.47,  0.43,  0.42 ]
   b = [  0   ,  0   , -0.32, -0.15,  0.28,  0.26 ]
   c = [  0   ,  0   ,  0.39,  0.17, -0.25, -0.35 ]
   d = [  0.6 , -0.5 ,  0.38,  0.42,  0.45,  0.31 ]
   e = [  0   ,  0   ,  0   ,  0   ,  0   ,  0    ]
   f = [  0   ,  1   ,  0.6 ,  1.1 ,  1   ,  0.7  ]

#endif
=end