GLE Example: sierpinski.gle

[PDF file]

 

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size 10 8.75

wd = 4.75; ad = 0.2
set lwidth 0.01 cap round

sub a_line x0 y0 x1 y1
  amove x0 y0
  aline x1 y1
end sub

sub sierpinski x_left x_right y_bot y_top d
  if d > 0 then
    set color rgb(1/(d+ad),0,0)
    local y_c = (y_bot+y_top)/2     ! middle y coordinate
    local x_c = (x_left+x_right)/2  ! middle x coordinate
    local x_1 = (x_left+x_c)/2      ! 1/3 x coordinate
    local x_2 = (x_c+x_right)/2     ! 2/3 x coordinate
    a_line x_c y_bot x_1 y_c
    a_line x_1 y_c   x_2 y_c
    a_line x_2 y_c   x_c y_bot
    sierpinski x_left x_c     y_bot y_c   d-1 ! lower left triangle
    sierpinski x_c    x_right y_bot y_c   d-1 ! lower right triangle
    sierpinski x_1    x_2     y_c   y_top d-1 ! top triangle
  end if
end sub

x_left  = pagewidth()/2 - wd
y_bot   = pageheight()/2 - wd*sin(torad(60))
y_top   = y_bot + 2*wd*sin(torad(60))
x_right = x_left + wd*2
x_c     = x_left + wd

a_line x_left  y_bot x_c     y_top
a_line x_c     y_top x_right y_bot
a_line x_right y_bot x_left  y_bot

sierpinski x_left x_right y_bot y_top 7

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