#!/bin/bash
#
# This file echoes four gradients with 24-bit color codes
# to the terminal to demonstrate their functionality.
# The foreground escape sequence is ^[38;2;<r>;<g>;<b>m
# The background escape sequence is ^[48;2;<r>;<g>;<b>m
# <r> <g> <b> range from 0 to 255 inclusive.
# The escape sequence ^[0m returns output to defaultSEPARATOR=':'setBackgroundColor()
{echo -en "\x1b[48${SEPARATOR}2${SEPARATOR}$1${SEPARATOR}$2${SEPARATOR}$3""m"
}resetOutput()
{echo -en "\x1b[0m\n"
}# Gives a color $1/255 % along HSV
# Who knows what happens when $1 is outside 0-255
# Echoes "$red $green $blue" where
# $red $green and $blue are integers
# ranging between 0 and 255 inclusive
rainbowColor()
{ let h=$1/43let f=$1-43*$hlet t=$f*255/43let q=255-tif [ $h -eq 0 ]thenecho "255 $t 0"elif [ $h -eq 1 ]thenecho "$q 255 0"elif [ $h -eq 2 ]thenecho "0 255 $t"elif [ $h -eq 3 ]thenecho "0 $q 255"elif [ $h -eq 4 ]thenecho "$t 0 255"elif [ $h -eq 5 ]thenecho "255 0 $q"else# execution should never reach hereecho "0 0 0"fi
}for i in `seq 0 127`; dosetBackgroundColor $i 0 0echo -en " "
done
resetOutput
for i in `seq 255 128`; dosetBackgroundColor $i 0 0echo -en " "
done
resetOutputfor i in `seq 0 127`; dosetBackgroundColor 0 $i 0echo -n " "
done
resetOutput
for i in `seq 255 128`; dosetBackgroundColor 0 $i 0echo -n " "
done
resetOutputfor i in `seq 0 127`; dosetBackgroundColor 0 0 $iecho -n " "
done
resetOutput
for i in `seq 255 128`; dosetBackgroundColor 0 0 $iecho -n " "
done
resetOutputfor i in `seq 0 127`; dosetBackgroundColor `rainbowColor $i`echo -n " "
done
resetOutput
for i in `seq 255 128`; dosetBackgroundColor `rainbowColor $i`echo -n " "
done
resetOutput
