ingie's OpenComputers Palette Based Hologram Animations

-- from https://oc.cil.li/index.php?/topic/267-palette-based-hologram-animations/
--[[holo-wave.lua]]--

local keyboard = require("keyboard")
local component = require("component")
local hologram = component.hologram

hologram.clear()

-- because tau is better than Pi
local tau = math.pi * 2

-- magic numbers
local scale = 10 -- the size of the hologram
local offset = 20 -- the hologram offset from zero which is the zero axis of the sine wave

-- our colours
local dark = 0 -- palette value for "off"
local dim = 0x661133 -- palette value for "nearly off" - change this to 0 for a less subtle animation
local light = 0xff0000 -- palette value for "on"


-- draw our sine waves
-- no need to do it 3 times, but this is an offset to the sin function/voxel position, which makes the image "thicker"
for n = 1,3 do

  os.sleep(0.01)

    for x = 1,48 do
      for y = 1,48 do

        -- you do the math[s] - the principle is simple sin(x) varies from 0 to 1,
        -- but we want to scale that up, hence the scale
        local z = math.sin( ( y - x + n) / tau ) * scale + offset

        -- this might look tricky, but tis just getting the next colour in a sequence of
        -- 1,2,3,1,2,3,1,2,3... etc... in a way which matches the angle of the wave
        -- play with the formula [leaving the %3 + 1 bit] to get funkier ripples
        local col = (( y - x + n) % 3) + 1

        hologram.set( x, z, y, col)

        if keyboard.isKeyDown(keyboard.keys.q) then -- quicktime event "press q to die" ;)
          break
        end

      end
    end
end

-- do the animation, i have set this to just 100 for a demo...
-- loop if forever if you want, but beware, there is no yielding for the purposes of speed/smoothness
for n = 1, 100 do

-- the % [modulo] bits here are just to get a sequence as 1,2,3 : 2,3,1 : 3,1,2 : 1,2,3 etc..
-- for each of the 3 colours [including dark/off]
  hologram.setPaletteColor(((n-2) % 3) + 1,dark)
  hologram.setPaletteColor(((n-1) % 3) + 1,dim)
  hologram.setPaletteColor((n % 3) + 1,light)

end