COLORS

A color on a screen is three amounts of light: red, green and blue. Written in hexadecimal, each amount takes two digits, from 00 (none) to FF (full), so a whole color is six hex digits. 87CEEB is a sky blue, FF0000 is pure red, and 000000 is black. satellite.variable.color holds exactly that, and satellite.variable.colour is its second spelling.

Making a color

On the line that declares a color, the x in front is optional: 000000, x000000, ff00aa and 87ceeb all work. However you write it, a color is shown in capitals with its x, the way a hex number is.

A color can also be see-through. Its transparency is a whole number from 0 (solid) to 99 (almost clear). You can give it after a comma when you write the color, or set it later with .transparency(n). Written on its own, .transparency reads it back.

satellite.include(satellite)

satellite.capsule satellite.main()
{
    satellite.variable.color sky = 87ceeb
    satellite.variable.colour ink = x000000, 50
    satellite.console.display(sky)
    satellite.console.display(ink)
    satellite.console.display(ink.transparency)
    sky.transparency(40)
    satellite.console.display(sky.transparency)
    satellite.console.display(sky)
    satellite.return(satellite)
}

x87CEEB
x000000, 50
50
40
x87CEEB, 40

A color with a transparency shows as x000000, 50, just the way you write it.

Changing a color later

On a later line, c = x00ff00 always works, and so do digits that start with a letter, or that have no letters at all, such as c = abcdef and c = 123456. The one shape that needs its x is digits that start with a number and hold a letter, such as 00ff00. The comma works on a later line too.

satellite.include(satellite)

satellite.capsule satellite.main()
{
    satellite.variable.color grass = 00ff00
    satellite.console.display(grass)
    grass = x228b22
    satellite.console.display(grass)
    grass = abcdef
    satellite.console.display(grass)
    grass = 123456, 10
    satellite.console.display(grass)
    satellite.return(satellite)
}

x00FF00
x228B22
xABCDEF
x123456, 10

Comparing and converting

== and != compare two colors, and both the digits and the transparency have to match. A color has no order, so < and > are refused, and it has no arithmetic: + on two colors is refused, and the message points you to .number if you want to do sums.

• .number is what the six digits are worth
• .hex is the six digits, without the x
• .binary is its 24 bits
• .string is the color as it is shown

satellite.include(satellite)

satellite.capsule satellite.main()
{
    satellite.variable.color red = ff0000
    satellite.variable.color also_red = xFF0000
    satellite.variable.color glass = ff0000, 30
    satellite.console.display(red == also_red)
    satellite.console.display(red == glass)
    satellite.console.display(red.number)
    satellite.console.display(red.hex)
    satellite.console.display(red.binary)
    satellite.console.display(glass.string)
    satellite.return(satellite)
}

true
false
16711680
FF0000
111111110000000000000000
xFF0000, 30

red and glass have the same digits, but glass is 30 see-through, so they are not equal.

Six digits exactly

A color is always six digits. Five or seven are refused before the program starts:

satellite.include(satellite)

satellite.capsule satellite.main()
{
    satellite.variable.color pink = ff00a
    satellite.console.display(pink)
    satellite.return(satellite)
}

--------------------------------------------------------------------------------
SATELLITE CRITICAL ERROR REPORT
--------------------------------------------------------------------------------
S301: TYPES_DO_NOT_MEET
satl(check): in satellite.main, ERROR: ff00a is 5 hex digits -- a color is
exactly six hex digits, like x00FF00

directory: short.satl:5
syntax: satellite.variable.color pink = ff00a
        /\

this operator has no scenario for the two kinds it was given. Nothing was
guessed at, because a guess here is an answer that is wrong and does not say so.
machine code 27 types_do_not_meet -- satl exits with this.

--------------------------------------------------------------------------------

A transparency of 100 or more is refused the same way: the most is 99.

Using a color

A color is what you hand to the words that paint text. "OK".foreground(grass) is the word OK in the color grass holds, and six hex digits work there too: "OK".foreground(x00FF00) is OK in green. The color shows when the text reaches a terminal. See COLOR ON THE CONSOLE.

Comparing a color with a bare hex number, such as grass == x228B22, is not built yet. Compare two colors instead, or compare their .number values.

Where next

The FULL REFERENCE lists every color word. Hex numbers themselves are in BINARY AND HEXADECIMAL.