Skip to content

Instantly share code, notes, and snippets.

@byates

byates/test-24-bit-color.sh

Created June 16, 2025 18:09
Show Gist options
  • Save byates/b6ded34f2c7436cac9898d92abb8a0d1 to your computer and use it in GitHub Desktop.
Save byates/b6ded34f2c7436cac9898d92abb8a0d1 to your computer and use it in GitHub Desktop.
Download ZIP

Revisions

  1. byates created this gist Jun 16, 2025.
    98 changes: 98 additions & 0 deletions test-24-bit-color.sh
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,98 @@
    #!/bin/bash
    #
    # This file echoes a bunch of 24-bit color codes
    # to the terminal to demonstrate its 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 default

    setBackgroundColor()
    {
    echo -en "\x1b[48;2;$1;$2;$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=$1/43
    let f=$1-43*$h
    let t=$f*255/43
    let q=255-t

    if [ $h -eq 0 ]
    then
    echo "255 $t 0"
    elif [ $h -eq 1 ]
    then
    echo "$q 255 0"
    elif [ $h -eq 2 ]
    then
    echo "0 255 $t"
    elif [ $h -eq 3 ]
    then
    echo "0 $q 255"
    elif [ $h -eq 4 ]
    then
    echo "$t 0 255"
    elif [ $h -eq 5 ]
    then
    echo "255 0 $q"
    else
    # execution should never reach here
    echo "0 0 0"
    fi
    }

    for i in `seq 0 127`; do
    setBackgroundColor $i 0 0
    echo -en " "
    done
    resetOutput
    for i in `seq 255 128`; do
    setBackgroundColor $i 0 0
    echo -en " "
    done
    resetOutput

    for i in `seq 0 127`; do
    setBackgroundColor 0 $i 0
    echo -n " "
    done
    resetOutput
    for i in `seq 255 128`; do
    setBackgroundColor 0 $i 0
    echo -n " "
    done
    resetOutput

    for i in `seq 0 127`; do
    setBackgroundColor 0 0 $i
    echo -n " "
    done
    resetOutput
    for i in `seq 255 128`; do
    setBackgroundColor 0 0 $i
    echo -n " "
    done
    resetOutput

    for i in `seq 0 127`; do
    setBackgroundColor `rainbowColor $i`
    echo -n " "
    done
    resetOutput
    for i in `seq 255 128`; do
    setBackgroundColor `rainbowColor $i`
    echo -n " "
    done
    resetOutput