#!/bin/bash

# lines (draw some lines)

# usage: lines out.png

# var
out="$1"

# make empty image
convert -size 1920x1 xc:black "$out"

# random
random () {
    # 0 - 255
    r=$(( RANDOM % 256 ))
    g=$(( RANDOM % 256 ))
    b=$(( RANDOM % 256 ))

    # 1 - 100
    linewidth=$(( RANDOM % 60 + 1 ))

    # 0 - 1920
    linepos=$(( RANDOM % 1921 ))
}

set -x
# action
for ((i=1;i<=200;i++)); 
do
    echo "$i"
    random
    mogrify -stroke "rgba(${r},${g},${b},0.5)" -linewidth "${linewidth}" \
    -draw "line ${linepos},0 ${linepos},10" "$out"

done

# bw
mogrify -scale 1920x1200\! -auto-level -colorspace gray "$out"