Overview
| Comment: | feat(color): Change color lightening to use HSL Change color lightening, including the readable utility, to use HSL. This is because the earlier implementation was broken and hacky, and using HSL is a way to implement this in a much more natural-feeling way (being closer to percieved lightness), especially for the current uses. Add a color:to_hsl() function to make this easier, as well as a from_hsl utility that is only in color, for now, but maybe should be exposed as an alternate constructor? |
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| Timelines: | family | ancestors | descendants | both | glowpelt/hsl |
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| SHA3-256: |
0a49ac4849099b7ab705e205893c11f7 |
| User & Date: | glowpelt on 2020-08-13 05:11:22 |
| Other Links: | branch diff | manifest | tags |
Context
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2020-08-14
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| 06:17 | fix(color): Actually get hsl brightening working Reimplemented based on the algorithms in Computer Graphics: Principles and Practice. Only lightens based on luminosity right now, which makes beautifully saturated, but not pastel colors, so some tweaking might be recommended. Leaf check-in: 794d5b023a user: glowpelt tags: glowpelt/hsl | |
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2020-08-13
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| 05:11 | feat(color): Change color lightening to use HSL Change color lightening, including the readable utility, to use HSL. This is because the earlier implementation was broken and hacky, and using HSL is a way to implement this in a much more natural-feeling way (being closer to percieved lightness), especially for the current uses. Add a color:to_hsl() function to make this easier, as well as a from_hsl utility that is only in color, for now, but maybe should be exposed as an alternate constructor? check-in: 0a49ac4849 user: glowpelt tags: glowpelt/hsl | |
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2020-08-11
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| 21:39 | initial commit check-in: 956134c50b user: lexi tags: trunk | |
Changes
Modified lib/color.lua from [16b55419da] to [1e12e4a44b].
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} end; }; construct = function(r,g,b,a) local clip = function(v) return math.max(0,math.min(255,v)) end; local warp = function(f) return function(self, ...) local n = color(self) f(n, ...) return n end; end; ................................................................................ fmt = function(self, text) return minetest.colorize(self:hex(), text) end; luminosity = function(self) return (self.red + self.green + self.blue) / 3 end; readable = function(self, target) target = target or 200 local lum = self:luminosity() if lum < target then local f = 1.0 + (target - lum) / 255 local nc = self:brighten(f * 1.5) -- i don't know why the *1.5 is necessary. it's -- an ugly hack to work around broken math, -- because i'm too much of a mathtard to actually -- find what's wrong return nc else return self end end; bg = function(self, text) return text .. minetest.get_background_escape_sequence(self:hex()) end; fade = warp(function(new, fac) new.alpha = math.min(255, (new.alpha or 255) * fac) end); brighten = warp(function(new, fac) local lum = new:luminosity() local newlum = lum * fac local delta = (newlum - lum) new.red = clip(new.red + delta) new.blue = clip(new.blue + delta) new.green = clip(new.green + delta) end); darken = warp(function(new, fac) new.red = clip(new.red - (new.red * fac)) new.blue = clip(new.blue - (new.blue * fac)) new.green = clip(new.green - (new.green * fac)) end); } if g == nil then if type(r) == 'string' then |
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} end; }; construct = function(r,g,b,a) local clip = function(v) return math.max(0,math.min(255,v)) end; local from_hsl = function(hsl, alpha) -- convert from a hsl table and alpha value to a color local weird = function(n) -- Yeah... this is a really weird function, only named f local k = math.fmod(n + hsl.hue/(math.pi/6),12) local a = hsl.saturation * math.min(hsl.luminosity, 1 - hsl.luminosity) return hsl.luminosity * math.max(-1, math.min(k-3,9-k,1)) end return color(clip(weird(0)*255), clip(weird(8)*255), clip(weird(4)*255), alpha) end; local warp = function(f) return function(self, ...) local n = color(self) f(n, ...) return n end; end; ................................................................................ fmt = function(self, text) return minetest.colorize(self:hex(), text) end; luminosity = function(self) return (self.red + self.green + self.blue) / 3 end; to_hsl = function(self) -- https://en.wikipedia.org/wiki/HSL_and_HSV -- www.niwa.nu/2013/05/math-behind-colorspace-conversions-rgb-hsl/ -- https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.211.6425 -- https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.413.9004 -- We need the rgb between 0 and 1 local rgb = { r = self.red/255, g = self.green/255, b = self.blue/255 } -- First, the hue. -- This version of the calculation can be up to 1.12deg off at the right few colors -- but is overall very close, easier to implement, and runs much faster -- TODO: consider memoizing something to do with this all? local alpha = 0.5 * (2*rgb.r - rgb.g - rgb.b) local beta = (math.sqrt(3)/2)*(rgb.g - rgb.b) local hue = math.atan2(beta, alpha) -- Next the luminosity/lightness. This one's easy enough local luminosity = 0.5*(math.max(rgb.r, rgb.g, rgb.b) + math.min(rgb.r, rgb.g, rgb.b)) -- Finally, saturation local saturation = 0 -- If luminosity isn't essentially 1 or 0 if math.abs(luminosity - 1) < 1e-18 or math.abs(luminosity) < 1e-18 then -- need the chroma local chroma = math.max(rgb.r,rgb.g,rgb.b) - math.min(rgb.r,rgb.g,rgb.b) saturation = chroma / (1 - math.abs(2*luminosity - 1)) end return { hue = hue, saturation = saturation, luminosity = luminosity } end; readable = function(self, target) target = target or 200 local hsl = self:to_hsl() hsl.luminosity = target return from_hsl(hsl, self.alpha) end; bg = function(self, text) return text .. minetest.get_background_escape_sequence(self:hex()) end; fade = warp(function(new, fac) new.alpha = math.min(255, (new.alpha or 255) * fac) end); brighten = function(self, fac) -- Use HSL to brighten -- To HSL local hsl = self:to_hsl() -- Do the calculation, clamp to 0-1 instead of the clamp fn hsl.luminosity = math.max(math.min(hsl.luminosity * fac, 0), 1) -- Turn back into RGB color return from_hsl(hsl, self.alpha) end; darken = warp(function(new, fac) -- TODO: is there any point to this being different than brighten? Probably especially not now. new.red = clip(new.red - (new.red * fac)) new.blue = clip(new.blue - (new.blue * fac)) new.green = clip(new.green - (new.green * fac)) end); } if g == nil then if type(r) == 'string' then |