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[modified] colour fairly extensively; renamed functions to same snake_case convention as other modules

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[added] colour.hsl_to_rgb
This commit is contained in:
Max Cahill 2020-06-15 21:11:05 +10:00
parent 77fa7b4288
commit ba221060c5
1 changed files with 76 additions and 22 deletions
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96
colour.lua
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@ -1,23 +1,40 @@
--[[
colour handling stuff
feel free to alias to `color` :)
]]
local path = (...):gsub("colour", "")
local bit = require("bit")
local band, bor = bit.band, bit.bor
local lshift, rshift = bit.lshift, bit.rshift
local math = require(path.."mathx")
local colour = {}
function colour.packRGB(r, g, b)
-------------------------------------------------------------------------------
-- hex handling routines
-- pack and unpack into 24 or 32 bit hex numbers
--rgb only (no alpha)
function colour.pack_rgb(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)
function colour.unpack_rgb(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
return r, g, b
end
--argb format (common for shared hex)
function colour.pack_argb(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)
@ -25,15 +42,7 @@ function colour.packARGB(r, g, b, a)
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)
function colour.unpack_argb(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
@ -41,7 +50,17 @@ function colour.unpackARGB(argb)
return r, g, b, a
end
function colour.unpackRGBA(rgba)
--rgba format
function colour.pack_rgba(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.unpack_rgba(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
@ -49,14 +68,49 @@ function colour.unpackRGBA(rgba)
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
-------------------------------------------------------------------------------
-- colour space conversion
-- rgb is the common language but it's useful to have other spaces to work in
-- for us as humans :)
--convert hsl to rgb
--all components are 0-1, hue is fraction of a turn rather than degrees or radians
function colour.hsl_to_rgb(h, s, l)
--wedge slice
local w = (math.wrap(h, 0, 1) * 6)
--chroma
local c = (1 - math.abs(2 * l - 1)) * s
--secondary
local x = c * (1 - math.abs(w % 2 - 1))
--lightness boost
local m = l - c / 2
--per-wedge logic
local r, g, b = m, m, m
if w < 1 then
r = r + c
g = g + x
elseif w < 2 then
r = r + x
g = g + c
elseif w < 3 then
g = g + c
b = b + x
elseif w < 4 then
g = g + x
b = b + c
elseif w < 5 then
b = b + c
r = r + x
else
b = b + x
r = r + c
end
return r, g, b
end
--todo: hsl, hsv, other colour spaces
--todo: rgb to hsl
--todo: hsv, other colour spaces
return colour