batteries/colour.lua

62 lines
1.7 KiB
Lua

--[[
colour handling stuff
feel free to alias to colour
]]
local bit = require("bit")
local band, bor = bit.band, bit.bor
local lshift, rshift = bit.lshift, bit.rshift
local colour = {}
function colour.packRGB(r, g, b)
local br = lshift(band(0xff, r * 255), 16)
local bg = lshift(band(0xff, g * 255), 8)
local bb = lshift(band(0xff, b * 255), 0)
return bor( br, bg, bb )
end
function colour.packARGB(r, g, b, a)
local ba = lshift(band(0xff, a * 255), 24)
local br = lshift(band(0xff, r * 255), 16)
local bg = lshift(band(0xff, g * 255), 8)
local bb = lshift(band(0xff, b * 255), 0)
return bor( br, bg, bb, ba )
end
function colour.packRGBA(r, g, b, a)
local br = lshift(band(0xff, r * 255), 24)
local bg = lshift(band(0xff, g * 255), 16)
local bb = lshift(band(0xff, b * 255), 8)
local ba = lshift(band(0xff, a * 255), 0)
return bor( br, bg, bb, ba )
end
function colour.unpackARGB(argb)
local r = rshift(band(argb, 0x00ff0000), 16) / 255.0
local g = rshift(band(argb, 0x0000ff00), 8) / 255.0
local b = rshift(band(argb, 0x000000ff), 0) / 255.0
local a = rshift(band(argb, 0xff000000), 24) / 255.0
return r, g, b, a
end
function colour.unpackRGBA(rgba)
local r = rshift(band(rgba, 0xff000000), 24) / 255.0
local g = rshift(band(rgba, 0x00ff0000), 16) / 255.0
local b = rshift(band(rgba, 0x0000ff00), 8) / 255.0
local a = rshift(band(rgba, 0x000000ff), 0) / 255.0
return r, g, b, a
end
function colour.unpackRGB(rgb)
local r = rshift(band(rgb, 0x00ff0000), 16) / 255.0
local g = rshift(band(rgb, 0x0000ff00), 8) / 255.0
local b = rshift(band(rgb, 0x000000ff), 0) / 255.0
local a = 1.0
return r, g, b, a
end
--todo: hsl, hsv, other colour spaces
return colour