Skip to contents

Convert colours to Amiga compatible raw data or vice versa

Source: R/generic_support.r
colourToAmigaRaw.Rd

Convert colours to Amiga compatible raw data or vice versa, such that it can be used in graphical objects from the Commodore Amiga.

Usage

colourToAmigaRaw(
  x,
  colour.depth = c("12 bit", "24 bit"),
  n.bytes = c("2", "3")
)

amigaRawToColour(
  x,
  colour.depth = c("12 bit", "24 bit"),
  n.bytes = c("2", "3")
)

Arguments

x

In the case amigaRawToColour is called, x should be a vector of raw data. The length of this vector should be a multiple of 2 (when n.bytes = "2") or 3 (when n.bytes = "3"). When colourToAmigaRaw is called, x should be a character strings representing a colour.

colour.depth

A character string: "12 bit" (default) or "24 bit". The first should be used in most cases, as old Amigas have a 12 bit colour depth.

n.bytes

A character string: "2" or "3". The number of bytes that is used or should be used to store each colour.

Value

In the case amigaRawToColour is called, a (vector of) colour character string(s) is returned. When colourToAmigaRaw

is called, raw representing the colour(s) specified in x is returned.

Details

On the original Commodore Amiga chipset, graphics used indexed palettes of 12 bit colours. Colours are specified by their RGB (Red, Green and Blue) values, each component requiring 4 bits (with corresponding values ranging from 0 up to 15). Data structures on the Amiga were WORD (2 bytes) aligned. Colours are therefore typically stored in either 2 bytes (skipping the first four bits) or 3 bytes (one byte for each value).

These functions can be used to convert R colours into the closest matching Amiga colour in a raw format, or vice versa. Note that later Amiga models with the advanced (graphics) architecture (known as AA or AGA) allowed for 24 bit colours.

See also

Other raw.operations: as.AmigaBasic(), as.raw.AmigaBasic(), packBitmap(), rawToAmigaBasicBMAP(), rawToAmigaBasicShape(), rawToAmigaBasic(), rawToAmigaBitmapFontSet(), rawToAmigaBitmapFont(), rawToAmigaIcon(), rawToHWSprite(), rawToIFFChunk(), rawToSysConfig(), simpleAmigaIcon()

Author

Pepijn de Vries

Examples

## Let's create some Amiga palettes:
colourToAmigaRaw(c("red", "navy blue", "brown", "#34AC5A"))
#> [1] 0f 00 00 08 0a 22 03 a5

## let's do the reverse.
## this is white:
amigaRawToColour(as.raw(c(0x0f, 0xff)))
#> [1] "#FFFFFF"

## this is white specified in 3 bytes:
amigaRawToColour(as.raw(c(0xf0, 0xf0, 0xf0)), n.bytes = "3")
#> [1] "#FFFFFF"

## lower nybbles are ignored, you will get a warning when it is not zero:
amigaRawToColour(as.raw(c(0xf0, 0xf0, 0x0f)), n.bytes = "3")
#> Warning: The low nybble is not zero for all colours.
#> [1] "#FFFF00"