mirror of
https://github.com/1bardesign/batteries.git
synced 2024-11-10 02:31:48 +00:00
140 lines
3.4 KiB
Lua
140 lines
3.4 KiB
Lua
--[[
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colour handling stuff
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]]
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local path = (...):gsub("colour", "")
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local bit = require("bit")
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local band, bor = bit.band, bit.bor
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local lshift, rshift = bit.lshift, bit.rshift
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local math = require(path.."mathx")
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local colour = {}
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-------------------------------------------------------------------------------
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-- hex handling routines
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-- pack and unpack into 24 or 32 bit hex numbers
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--rgb only (no alpha)
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function colour.pack_rgb(r, g, b)
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local br = lshift(band(0xff, r * 255), 16)
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local bg = lshift(band(0xff, g * 255), 8)
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local bb = lshift(band(0xff, b * 255), 0)
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return bor( br, bg, bb )
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end
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function colour.unpack_rgb(rgb)
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local r = rshift(band(rgb, 0x00ff0000), 16) / 255.0
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local g = rshift(band(rgb, 0x0000ff00), 8) / 255.0
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local b = rshift(band(rgb, 0x000000ff), 0) / 255.0
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return r, g, b
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end
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--argb format (common for shared hex)
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function colour.pack_argb(r, g, b, a)
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local ba = lshift(band(0xff, a * 255), 24)
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local br = lshift(band(0xff, r * 255), 16)
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local bg = lshift(band(0xff, g * 255), 8)
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local bb = lshift(band(0xff, b * 255), 0)
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return bor( br, bg, bb, ba )
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end
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function colour.unpack_argb(argb)
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local r = rshift(band(argb, 0x00ff0000), 16) / 255.0
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local g = rshift(band(argb, 0x0000ff00), 8) / 255.0
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local b = rshift(band(argb, 0x000000ff), 0) / 255.0
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local a = rshift(band(argb, 0xff000000), 24) / 255.0
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return r, g, b, a
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end
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--rgba format
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function colour.pack_rgba(r, g, b, a)
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local br = lshift(band(0xff, r * 255), 24)
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local bg = lshift(band(0xff, g * 255), 16)
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local bb = lshift(band(0xff, b * 255), 8)
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local ba = lshift(band(0xff, a * 255), 0)
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return bor( br, bg, bb, ba )
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end
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function colour.unpack_rgba(rgba)
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local r = rshift(band(rgba, 0xff000000), 24) / 255.0
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local g = rshift(band(rgba, 0x00ff0000), 16) / 255.0
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local b = rshift(band(rgba, 0x0000ff00), 8) / 255.0
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local a = rshift(band(rgba, 0x000000ff), 0) / 255.0
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return r, g, b, a
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end
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-------------------------------------------------------------------------------
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-- colour space conversion
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-- rgb is the common language but it's useful to have other spaces to work in
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-- for us as humans :)
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--convert hsl to rgb
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--all components are 0-1, hue is fraction of a turn rather than degrees or radians
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function colour.hsl_to_rgb(h, s, l)
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--wedge slice
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local w = (math.wrap(h, 0, 1) * 6)
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--chroma
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local c = (1 - math.abs(2 * l - 1)) * s
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--secondary
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local x = c * (1 - math.abs(w % 2 - 1))
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--lightness boost
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local m = l - c / 2
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--per-wedge logic
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local r, g, b = m, m, m
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if w < 1 then
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r = r + c
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g = g + x
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elseif w < 2 then
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r = r + x
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g = g + c
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elseif w < 3 then
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g = g + c
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b = b + x
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elseif w < 4 then
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g = g + x
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b = b + c
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elseif w < 5 then
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b = b + c
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r = r + x
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else
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b = b + x
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r = r + c
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end
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return r, g, b
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end
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--todo: rgb to hsl
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--todo: hsv, other colour spaces
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--todo: oklab https://bottosson.github.io/posts/oklab/
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--colour distance functions
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--distance of one colour to another (linear space)
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--can be used for finding nearest colours for palette mapping, for example
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function colour.distance_rgb(
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ar, ag, ab,
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br, bg, bb
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)
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local dr, dg, db = ar - br, ag - bg, ab - bb
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return math.sqrt(dr * dr + dg * dg + db * db)
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end
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function colour.distance_packed_rgb(a, b)
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local ar, ag, ab = colour.unpack_rgb(a)
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local br, bg, bb = colour.unpack_rgb(b)
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return colour.distance_rgb(
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ar, ag, ab,
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br, bg, bb
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)
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end
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--todo: rgba and various other unpacks
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return colour
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