GLua code for fast conversion between RGB / HSV without using Color objects

color_conversion.lua

-- Color conversion (CC0 Public Domain, free to use in whatever you want)
-- Created by: Zachary Blystone ( [email protected] )

local _min, _max, _abs, _floor = math.min, math.max, math.abs, math.floor
local _permut = {
	function(a,b,c) return a,b,c end,
	function(a,b,c) return b,a,c end,
	function(a,b,c) return c,a,b end,
	function(a,b,c) return c,b,a end,
	function(a,b,c) return b,c,a end,
	function(a,b,c) return a,c,b end,
}

local function rgb(h,s,v)

	h = h % 360 / 60
	local x = v * s * _abs(h % 2 - 1)
	return _permut[1+_floor(h)](v,v-x,v-v*s)

end

local function hsv(r,g,b)

	local v = _max(r,g,b)
	local c = v - _min(r,g,b)
	if c * v == 0 then return 0, 0, v
	elseif v == r then return 60 * (g-b) / c % 360, c/v, v
	elseif v == g then return 120 + 60 * (b-r) / c, c/v, v
	elseif v == b then return 240 + 60 * (r-g) / c, c/v, v
	end

end