c0=!random -$yrange+0.5,$yrange-0.5
flist=$[ceil(-$xrange)],$c0
r=$[$yrange-0.1]

step=!item $level of 2,2,1,1,1,1,0.5,0.5,0.5,0.5

!for i=ceil(-$xrange) to floor($xrange)-$step step $step
 c_=!random max(-$r,$c0-$r*$step),min($r,$c0+$r*$step)
 d_=$[($c_-($c0))/$step]
 flist=$flist,$[$i+$step],$c_
 dlist=!append item $i,$d_,$[$i+$step],$d_ to $dlist
 x1=$[floor(($xrange+$i)*$size/(2*$xrange))]
 x2=$[floor(($xrange+$i+$step)*$size/(2*$xrange))]
 y_=$[floor(-($d_-$xrange)*$size/(2*$xrange))]
 compstr=!append item $x1,$y_,$x2,$y_ to $compstr
 c0=$c_
!next i

plot1=lines $color1,$flist
plot2=lines $color2,$dlist
