xn(x,y) = x - H*sin(y+tan(3*y))
yn(x,y) = y - H*sin(x+tan(3*x))
H = 0.05

set samples 40
set term pngc enh font "Arial,8" size 480,480
set out "popcorn.png"
unset key
unset tics
unset border
set size square
set xrange [-3:3]
set yrange [-3:3]

N=70
set multiplot 
do for [i = 1:N**2] {
  xp = xc = 0.1*(i%N) - 0.05*N
  yp = yc = 0.1*(i/N) - 0.05*N
  plot '+' u (xc=xn(xp,yp), yc=yn(xp,yp), xc) : \
           (xp=xc,yp=yc,yc) w d lt i 
}
unset multiplot

!display popcorn.png