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keep both bitop and float-only pack/unpack functions in colour

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This commit is contained in:
Max Cahill 2022-09-13 11:15:08 +10:00
parent fabbd3f702
commit 4f86dc0a5e
1 changed files with 91 additions and 37 deletions
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68
colour.lua
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@ -13,10 +13,66 @@ local colour = {}
-- hex handling routines
-- pack and unpack into 24 or 32 bit hex numbers
local ok, bit = pcall(require, "bit")
if ok then
--we have bit operations module, use the fast path
local band, bor = bit.band, bit.bor
local lshift, rshift = bit.lshift, bit.rshift
--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.unpack_rgb(rgb)
local r = rshift(band(rgb, 0x00ff0000), 16) / 255
local g = rshift(band(rgb, 0x0000ff00), 8) / 255
local b = rshift(band(rgb, 0x000000ff), 0) / 255
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)
local bb = lshift(band(0xff, b * 255), 0)
return bor( br, bg, bb, ba )
end
function colour.unpack_argb(argb)
local r = rshift(band(argb, 0x00ff0000), 16) / 255
local g = rshift(band(argb, 0x0000ff00), 8) / 255
local b = rshift(band(argb, 0x000000ff), 0) / 255
local a = rshift(band(argb, 0xff000000), 24) / 255
return r, g, b, a
end
--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
local g = rshift(band(rgba, 0x00ff0000), 16) / 255
local b = rshift(band(rgba, 0x0000ff00), 8) / 255
local a = rshift(band(rgba, 0x000000ff), 0) / 255
return r, g, b, a
end
else
--we don't have bitops, use a slower pure-float path
local floor = math.floor
--rgb only (no alpha)
function colour.pack_rgb(r, g, b)
local br = floor(0xff * r) % 0x100 * 0x10000
local bg = floor(0xff * g) % 0x100 * 0x100
@ -32,7 +88,6 @@ function colour.unpack_rgb(rgb)
end
--argb format (common for shared hex)
function colour.pack_argb(r, g, b, a)
local ba = floor(0xff * a) % 0x100 * 0x1000000
return colour.pack_rgb(r, g, b) + ba
@ -45,7 +100,6 @@ function colour.unpack_argb(argb)
end
--rgba format
function colour.pack_rgba(r, g, b, a)
local ba = floor(0xff * a) % 0x100
return colour.pack_rgb(r, g, b) * 0x100 + ba
@ -56,12 +110,13 @@ function colour.unpack_rgba(rgba)
local a = floor(rgba) % 0x100
return r, g, b, a
end
end
-------------------------------------------------------------------------------
-- colour space conversion
-- rgb is the common language but it's useful to have other spaces to work in
-- for us as humans :)
-- rgb is the common language for computers
-- 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
@ -115,11 +170,10 @@ function colour.rgb_to_hsl(r, g, b)
else
h = (r - g) / d + 4
end
assert(h)
return h / 6, s, l
end
--todo: hsv, other colour spaces
--todo: hsv
--oklab https://bottosson.github.io/posts/oklab/
function colour.oklab_to_rgb(l, a, b)