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Old 03-21-2017, 02:10 PM   #15
amagalma
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Posts: 3,451
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Code:
-- https://github.com/EmmanuelOga/columns/blob/master/utils/color.lua

--[[
 * Converts an RGB color value to HSL. Conversion formula
 * adapted from http://en.wikipedia.org/wiki/HSL_color_space.
 * Assumes r, g, and b are contained in the set [0, 255] and
 * returns h, s, and l in the set [0, 1].
 *
 * @param   Number  r       The red color value
 * @param   Number  g       The green color value
 * @param   Number  b       The blue color value
 * @return  Array           The HSL representation
]]
function rgbToHsl(r, g, b, a)
  r, g, b = r / 255, g / 255, b / 255

  local max, min = math.max(r, g, b), math.min(r, g, b)
  local h, s, l

  l = (max + min) / 2

  if max == min then
    h, s = 0, 0 -- achromatic
  else
    local d = max - min
    local s
    if l > 0.5 then s = d / (2 - max - min) else s = d / (max + min) end
    if max == r then
      h = (g - b) / d
      if g < b then h = h + 6 end
    elseif max == g then h = (b - r) / d + 2
    elseif max == b then h = (r - g) / d + 4
    end
    h = h / 6
  end

  return h, s, l, a or 255
end

--[[
 * Converts an HSL color value to RGB. Conversion formula
 * adapted from http://en.wikipedia.org/wiki/HSL_color_space.
 * Assumes h, s, and l are contained in the set [0, 1] and
 * returns r, g, and b in the set [0, 255].
 *
 * @param   Number  h       The hue
 * @param   Number  s       The saturation
 * @param   Number  l       The lightness
 * @return  Array           The RGB representation
]]
function hslToRgb(h, s, l, a)
  local r, g, b

  if s == 0 then
    r, g, b = l, l, l -- achromatic
  else
    function hue2rgb(p, q, t)
      if t < 0   then t = t + 1 end
      if t > 1   then t = t - 1 end
      if t < 1/6 then return p + (q - p) * 6 * t end
      if t < 1/2 then return q end
      if t < 2/3 then return p + (q - p) * (2/3 - t) * 6 end
      return p
    end

    local q
    if l < 0.5 then q = l * (1 + s) else q = l + s - l * s end
    local p = 2 * l - q

    r = hue2rgb(p, q, h + 1/3)
    g = hue2rgb(p, q, h)
    b = hue2rgb(p, q, h - 1/3)
  end

  return r * 255, g * 255, b * 255, a * 255
end
--------------------------------------------------------------------------------
function Msg(name)
-- usage: Msg('') // put inside the '' what you want to get
  local value = _G[name]
  for i=1,math.huge do
    local localname, localvalue = debug.getlocal(2,i,1)
    if not localname then
      break -- no more locals to check
    elseif localname == name then
      value = localvalue
    end
  end
  if value then
    reaper.ShowConsoleMsg(string.format("%s = %s", name, tostring(value)).."\n")
  else
    reaper.ShowConsoleMsg(string.format("No variable named '%s' found.", name).."\n")
  end
end


----------------------------------------- TEST ---------------------------------
red = 120
green = 200
blue = 40

hue, sat, lum = rgbToHsl(red, green, blue)
Msg('hue')
Msg('sat')
Msg('lum')
Try this code to see

Edit: Found the mistake in his code: there is a "local s" that should not exist
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Last edited by amagalma; 03-21-2017 at 02:34 PM.
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