colour.lua

local com = require('component')
local term = require('term')
local os = require('os')
local args = { ... }
local gpu = com.gpu
local w,h = gpu.getResolution()

local red = {}
red[1] = 0 -- 00
red[2] = 3342336 -- 33
red[3] = 6684672 -- 66
red[4] = 10027008 -- 99
red[5] = 13369344 -- CC
red[6] = 16711680 -- FF

local green = {}
green[1] = 0 -- 00
green[2] = 9216 -- 24
green[3] = 18688 -- 49
green[4] = 27904 -- 6D
green[5] = 37376 -- 92
green[6] = 46592 -- B6
green[7] = 55296 -- DB
green[8] = 65280 -- FF

local blue = {}
blue[1] = 0 -- 00
blue[2] = 64 -- 40
blue[3] = 128 -- 80
blue[4] = 192 -- C0
blue[5] = 255 -- FF

local lumen = {}

function drawRect(colour)
  local old = gpu.getBackground()
  gpu.setBackground(colour)
  gpu.fill(w/4,h,w/2,1," ")
  gpu.setBackground(old)
end

function decHex(dec)
  local b,k,out,i,d=16,"0123456789ABCDEF","",0
  while dec>0 do
    i=i+1
    dec,d=math.floor(dec/b),dec%b+1
    out=string.sub(k,d,d)..out
  end
  return out
end

function pairsByKeys(t,f)
  local a = {}
  for n in pairs(t) do table.insert(a,n) end
  table.sort(a,f)
  local i = 0
  local iter = function()
    i = i + 1
    if a[i] == nil then return nil
    else return a[i], t[a[i]]
    end
  end
  return iter
end

if args[1] == "normal" then
  count = 1
  term.setCursor(1,h)
  for i=1,6 do
    for j=1,8 do
      for k=1,5 do
        local num = red[i]+green[j]+blue[k]
        drawRect(num)
        print(count, decHex(num))
        count = count + 1
        os.sleep(0.1)
      end
    end
  end
elseif args[1] == "lum" then
  count = 1
  term.setCursor(1,h)
  for i=1,6 do
    for j=1,8 do
      for k=1,5 do
        local num = red[i]+green[j]+blue[k]
        drawRect(num)
        local lum = math.sqrt(0.299*((red[i]/65536)^2)+0.587*((green[j]/256)^2)+(blue[k]^2))
        print(count, decHex(num), lum)
        lumen[lum] = num
        count = count + 1
        os.sleep(0.1)
      end
    end
  end
  for col,lumi in pairsByKeys(lumen) do
    print(col,decHex(lumi))
    drawRect(lumi)
    os.sleep(0.1)
  end
else
  print("Usage: colour normal")
  print("Usage: colour lum")
end