Analog Clock

function round(num, idp)
  local mult = 10^(idp or 0)
  return math.floor(num * mult + 0.5) / mult
end


print("       Analog Clock      ")
sleep(3.0)

gpuCount = 0
gpus = {}
gpuSide = ""

--detecting gpus

sides = {"back","front","left","right","top"}
for i = 1, 5, 1 do
  if peripheral.isPresent(sides[i]) then
    if peripheral.getType(sides[i]) == "gpu" then
      gpuCount = gpuCount + 1                             --increasing gpu count
      table.insert(gpus, (#gpus + 1), sides[i]) --adding gpu to list
    end
  end
end

--tell User
exit = false

if gpuCount == 0 then
  print("No gpu found!")
  exit = true
elseif (gpuCount > 1) then
  print("More than 1 gpu found!")
  print()
  local reading = true
  while reading do
    print("Please choose:")
    for i = 1, #gpus, 1 do
      print("GPU at side: " .. gpus[i])
    end
    print()
    gpuSide = read()

    for i = 1, #gpus, 1 do

      if gpuSide == gpus[i] then
        reading = false
      end
    end

    if reading == true then
      print("Invaild input!! Please repeat")
      sleep(1.5)
    end
  end

elseif gpuCount == 1 then
  gpuSide = gpus[1]
end

if not exit then
  print("GPU at side " .. gpuSide .. " selected")

  print("Hold [Ctrl] + [T] to terminate!")
  sleep(2)
  print("Starting Clock")

  while true do
    time = os.time()

    hours = math.floor(time)
    minutes = math.floor((time-hours)*60)


    --clocCode
      clockCode = "glColor3f(0,0.3,1) glBegin(GL_POINTS)"

      for i = 0,360,1 do
       clockCode = clockCode .. " glVertex2f(".. round(math.sin( math.rad(i) )*-63 + 63) .. ",".. round(math.cos( math.rad(i) )*-63 + 64)..")"
      end
      clockCode = clockCode .. " glEnd()"

    -- hourHand

      hourHand = " glColor3f(1,1,1) glBegin(GL_TRIANGLES)"

      hourHand = hourHand .. "  glVertex2f(".. round(math.sin( math.rad((hours % 12) * 30 - 2) )*63 + 63) .. ",".. round(math.cos( math.rad((hours % 12) * 30 - 2) )*-63 + 64) .. ")"
      hourHand = hourHand .. "  glVertex2f(".. round(math.sin( math.rad((hours % 12) * 30 + 2) )*63 + 63) .. ",".. round(math.cos( math.rad((hours % 12) * 30 + 2) )*-63 + 64) ..")"
      hourHand = hourHand .. "  glVertex2f(63,64)"

      hourHand = hourHand .. "  glEnd()"

    -- minuteHand

      minuteHand = " glColor3f(0.8,0,0.1) glBegin(GL_TRIANGLES)"

      minuteHand = minuteHand .. "  glVertex2f(".. round(math.sin( math.rad((minutes) * 6 - 1) )*63 + 63) .. ",".. round(math.cos( math.rad((minutes) * 6 - 1) )*-63 + 64) .. ")"
      minuteHand = minuteHand .. "  glVertex2f(".. round(math.sin( math.rad((minutes) * 6 + 1) )*63 + 63) .. ",".. round(math.cos( math.rad((minutes) * 6 + 1) )*-63 + 64) ..")"
      minuteHand = minuteHand .. "  glVertex2f(63,64)"

      minuteHand = minuteHand .. "  glEnd()"


    --EOF creating OPENGL code

    gpu.setRenderCode(gpuSide, [[

      gpuBindOutputBuffer(1)
      gpuClearBuffer()

      ]] .. clockCode .. " " .. hourHand .. " " .. minuteHand)

    sleep(0.001)
  end

end

print("Going down..")