Orologio Analogico 6x6

-- side of the computer that the monitor is attached to
local monitor = peripheral.wrap("back")
-- clock radius in character. 18 is good for a 6x6 advanced monitor
local nClockRad = 18
-- these two settings will hide/show
-- the M and H that is on the end of the hand
local bShowHourChar = false
local bShowMinuteChar = false

-- set up the screens
term.clear()
term.setCursorPos(1,1)
print("Orologio fatto da Mr.Alko99 2013")
print("Premi 'Q' per spegnere.")
term.redirect(monitor)
term.setBackgroundColor(colors.black)
term.clear()

-- some variables
local h = 0 -- parsed hour
local m = 0 -- parsed minute
local nOldHX = -1
local nOldHY = -1
local nOldMX = -1
local nOldMY = -1

local function plot(s,x,y)
  term.setCursorPos(x,y)
  term.write(s)
end

local function approx(v)
  if(v>=0) then
    return math.floor(v+0.5)
  else
    return math.ceil(v+0.5)
  end
end

local function line(x0, y0, x1, y1)
  if x0==x1 and y0==y1 then
    return false
  end

  if x0==x1 then
    if y0>y1 then
      inc=-1
    else
      inc=1
    end

    for y=y0,y1,inc do
      plot(".",x0,y)
    end

    return true
  end

  if y0==y1 then
    if x0>x1 then
      inc=-1
    else
      inc=1
    end

    for x=x0,x1,inc do
      plot(".",x,y0)
    end

    return true
  end

  if x0~=x1 and y0~=y1 then
    m=(y1-y0)/(x1-x0)

    if m<1 and m>-1 then
      n=y0-m*x0
      if x0>x1 then
        inc=-1
      else
        inc=1
      end

      for x=x0,x1,inc do
        y=m*x+n
        y=approx(y)
        plot(".",x,y)
      end
      return true
    else
      m=(x1-x0)/(y1-y0)
      n=x0-m*y0
      if y0>y1 then
        inc=-1
      else
        inc=1
      end

      for y=y0,y1,inc do
        x=m*y+n
        x=approx(x)
        plot(".",x,y)
      end
      return true
    end
  end
end

-- the clock face ticks
local function ticks(nW,nH)
  local nIndex
  local x
  local y
  local xi
  local yi
  local nInRadius = nClockRad-(nClockRad/4)
  local nOutRadius = nClockRad-1

  local nxOutRad = nOutRadius + (nOutRadius/2)
  local nyOutRad = nOutRadius
  local nxInRad = nInRadius + (nInRadius/2)
  local nyInRad = nInRadius

  for nIndex=0,359,(360/12) do
    term.setTextColor(colors.black)
    term.setBackgroundColor(colors.black)

    x = nW + math.sin(math.rad(nIndex)) * nxOutRad
    y = nH + math.cos(math.rad(nIndex)) * nyOutRad

    xi = nW + math.sin(math.rad(nIndex)) * nxInRad
    yi = nH + math.cos(math.rad(nIndex)) * nyInRad

    line(xi,yi,x,y)
  end
end

-- draw the face (circle)
-- which is essentially a line from
-- centre to all points on the circle
-- in character terms.  Who cares about
-- overlap ;)
local function face(nW,nH,nRadius)
  local nIndex
  local x
  local y
  local nxRad = nRadius + (nRadius/2)
  local nyRad = nRadius
  local nOldX = -1
  local nOldY = -1

  for nIndex=0,359 do
    x = nW + math.sin(math.rad(nIndex)) * nxRad
    y = nH + math.cos(math.rad(nIndex)) * nyRad

    -- the circle
    -- only do it if the positions are different from last time
    -- speeds things up a bit
    if x~=nOldX or y~=nOldY then
      term.setTextColor(colors.white)
      term.setBackgroundColor(colors.white)

      line(nW,nH,x,y)

      nOldX = x
      nOldY = y
    end
  end
end

-- parse the time into H and M
-- these are stored globally in h and m
local function parseTime()
  local t = os.time()
  local sT = textutils.formatTime(t, true)

  local n = string.find(sT, ":")

  if(n>0) then
    h = tonumber(string.sub(sT,1,n-1))
    m = tonumber(string.sub(sT,n+1))
  end
end

-- plot minute hand
-- it removes the previous minute hand
-- then draws the new one
local function plotM(nW,nH,nX,nY)
  if(nOldMX==nX and nOldMY==nY) then
    return
  end

  -- remove previous by drawing it again
  -- in the face colour.  Also remove the
  -- hand tag
  if(nOldMX~=-1) then
    term.setTextColor(colors.white)
    term.setBackgroundColor(colors.white)
    line(nW,nH,nOldMX,nOldMY)

    if(bShowMinuteChar) then
      plot(".",nOldMX,nOldMY)
    end
  end

  nOldMX = nX
  nOldMY = nY

  term.setTextColor(colors.black)
  term.setBackgroundColor(colors.black)
  line(nW,nH,nX,nY)

  -- draw the centre O
  term.setTextColor(colors.black)
  term.setBackgroundColor(colors.lightGray)
  plot("O",nW,nH)

  if(bShowMinuteChar) then
    -- draw the minute hand tag
    term.setTextColor(colors.black)
    term.setBackgroundColor(colors.lightGray)
    plot("M",nX,nY)
  end
end

-- plot hour hand
-- it removes the previous hour hand
-- then draws the new one
local function plotH(nW,nH,nX,nY)
  if(nOldHX==nX and nOldHY==nY) then
    return
  end

  -- remove previous by drawing it again
  -- in the face colour.  Also remove the
  -- hand tag
  if(nOldHX~=-1) then
    term.setTextColor(colors.white)
    term.setBackgroundColor(colors.white)
    line(nW,nH,nOldHX,nOldHY)

    if(bShowHourChar) then
      plot(".",nOldHX,nOldHY)
    end
  end

  nOldHX = nX
  nOldHY = nY

  term.setTextColor(colors.black)
  term.setBackgroundColor(colors.black)
  line(nW,nH,nX,nY)

  if(bShowHourChar) then
    -- draw the hour hand tag
    term.setTextColor(colors.black)
    term.setBackgroundColor(colors.lightGray)
    plot("H",nX,nY)
  end
end

local fH
local fM
local fXH
local fYH
local fXM
local fYM
local nyMRadius = nClockRad - (nClockRad / 4)
local nyHRadius = nClockRad - (nClockRad / 2)

local nxMRadius = nyMRadius + (nyMRadius / 2)
local nxHRadius = nyHRadius + (nyHRadius / 2)
local nW, nH = term.getSize()

nW = (nW / 2)+1
nH = (nH / 2)+1

-- plot the circle
face(nW,nH,nClockRad + 1)

local bRunning = true
local nTimer
nTimer = os.startTimer(0.25) -- the timer interval to update the clock

while(bRunning) do
  parseTime()

  fH = (((h % 12)/12) + (m/60/12)) * 360
  fM = (m/60) * 360

  -- shift by half a circle
  fH = fH + 180
  fM = fM + 180

  fXH = math.sin(math.rad(-fH))
  fYH = math.cos(math.rad(fH))
  fXM = math.sin(math.rad(-fM))
  fYM = math.cos(math.rad(fM))

  plotH(nW,nH,  nW + fXH * nxHRadius, nH + fYH * nyHRadius)
  plotM(nW,nH, nW + fXM * nxMRadius, nH + fYM * nyMRadius)

  -- draw the ticks on
  ticks(nW,nH)

  local event, param1 = os.pullEvent()

  while (not (event=="timer" and param1==nTimer) and event~="char") do
    event, param1 = os.pullEvent()
  end

  if(event=="char") then
     if(param1=="q" or param1=="Q") then
       bRunning=false
     end
  elseif(event=="timer" and param1==nTimer) then
     -- timer timed out, lets start again
     nTimer = os.startTimer(0.25)
  end
end

term.restore()
print("Ended.")