dd

-- initialize canvas
local function createCanvas(imageWidth, imageHeight)
  canvas = {width = imageWidth, height = imageHeight, blitStrings = "", blitFrontColors = "", image = {}}

  -- populate unused blit strings for optimization
  for x=1,imageWidth do
    canvas.blitStrings = canvas.blitStrings.." "
    canvas.blitFrontColors = canvas.blitFrontColors.."0"
  end

  -- clear color initialize
  for x=1,imageWidth do
    imageColumn = {}

    for y=1,imageHeight do
      imageColumn[y] = 0
    end

    canvas.image[x] = imageColumn
  end

  return canvas
end

local function clearCanvas(canvas, color)
  for x=1,canvas.width do
    for y=1,canvas.height do
      canvas.image[x][y] = color
    end
  end
end

local function drawDotCanvas(canvas, xPos, yPos, color)
  if xPos < 1 or xPos > canvas.width or yPos < 1 or yPos > canvas.height then
    return
  end

  canvas.image[xPos][yPos] = color
end

local function drawBoxCanvas(canvas, xPos, yPos, width, height, color)
  for x=xPos,xPos+width do
    drawDotCanvas(canvas, x, yPos, color)
  end

  for y=yPos+1,yPos+height-1 do
    drawDotCanvas(canvas, xPos, y, color)
    drawDotCanvas(canvas, xPos+width, y, color)
  end

  for x=xPos,xPos+width do
    drawDotCanvas(canvas, x, yPos+height, color)
  end
end

local function drawBoxFilledCanvas(canvas, xPos, yPos, width, height, color)
  for x=xPos,xPos+width do
    for y=yPos,yPos+height do
      drawDotCanvas(canvas, x, y, color)
    end
  end
end

local function drawLineCanvas(canvas, xStartingPos, yStartingPos, xEndPos, yEndPos, color)
  dx = xEndPos - xStartingPos
  dy = yEndPos - yStartingPos
  x = xStartingPos
  y = yStartingPos
  decisionFactor = 2 * dy - dx

  while x < xEndPos do
    drawDotCanvas(canvas, x, y, color)
    if decisionFactor >= 0 then
      y = y + 1
      decisionFactor = decisionFactor + 2 * dy - 2 * dx
    else
      decisionFactor = decisionFactor + 2 * dy
    end
    x = x + 1
  end
end

local function _drawCirclePartCanvas(canvas, xPos, yPos, xOffset, yOffset, color)
  drawDotCanvas(canvas, xPos+xOffset, yPos+yOffset, color)
  drawDotCanvas(canvas, xPos-xOffset, yPos+yOffset, color)
  drawDotCanvas(canvas, xPos+xOffset, yPos-yOffset, color)
  drawDotCanvas(canvas, xPos-xOffset, yPos-yOffset, color)
  drawDotCanvas(canvas, xPos+yOffset, yPos+xOffset, color)
  drawDotCanvas(canvas, xPos-yOffset, yPos+xOffset, color)
  drawDotCanvas(canvas, xPos+yOffset, yPos-xOffset, color)
  drawDotCanvas(canvas, xPos-yOffset, yPos-xOffset, color)
end

local function drawCircleCanvas(canvas, xPos, yPos, radius, color)
  xOffset = 0
  yOffset = radius
  decisionFactor = 3 - (2 * radius)

  _drawCirclePartCanvas(canvas, xPos, yPos, xOffset, yOffset, color)

  while yOffset >= xOffset do
    xOffset = xOffset + 1
    if decisionFactor > 0 then
      yOffset = yOffset - 1
      decisionFactor = decisionFactor + 4 * (xOffset - yOffset) + 10
    else
      decisionFactor = decisionFactor + 4 * xOffset + 6
    end
    _drawCirclePartCanvas(canvas, xPos, yPos, xOffset, yOffset, color)
  end
end

local function blitCanvas(canvas, terminalRedirect)
  for y=1,canvas.height do
    blitBackColors = ""
    for x=1,canvas.width do
      blitBackColors = blitBackColors..colors.toBlit(canvas.image[x][y])
    end

    terminalRedirect.setCursorPos(1,y)
    terminalRedirect.blit(canvas.blitStrings, canvas.blitFrontColors, blitBackColors)
  end
end


offset = 0
bottomMonitor = peripheral.wrap("top")
topMonitor = peripheral.find("monitor")

while true do
  timerID = os.startTimer(0.1)
  event, eventID = os.pullEvent("timer")

  topCanvas = createCanvas(29, 19)
  bottomCanvas = createCanvas(50, 33)

  clearCanvas(topCanvas, 2)
  clearCanvas(bottomCanvas, 4)

  drawCircleCanvas(topCanvas, 14, 9, 7, 2^((offset)%16))
  drawBoxCanvas(bottomCanvas, offset%bottomCanvas.width, offset%bottomCanvas.height, 4, 5, 2^((offset+1)%16))
  drawLineCanvas(bottomCanvas, 1, 1, 25, 6, 16)

  blitCanvas(topCanvas, topMonitor)
  blitCanvas(bottomCanvas, bottomMonitor)

  offset = offset + 1
end


--[[monitor = peripheral.wrap("top")
monitor2 = peripheral.find("monitor")
modem = peripheral.find("modem")
offset = 0

while true do
  timerID = os.startTimer(0.1)
  event, eventID = os.pullEvent("timer")

  for y=1,33 do
    spaces = ""
    frontColors = ""
    backColors = ""

    for x=1,50 do
      spaces = spaces.." "
      frontColors = frontColors.."0"

      if redstone.getInput("front") and x >= 20 and x <= 31 and y >= 6 and y <= 14 then
        backColors = backColors.."4"
      elseif redstone.getInput("back") and x >= 20 and x <= 31 and y >= 20 and y <= 28 then
        backColors = backColors.."4"
      elseif redstone.getInput("right") and x >= 9 and x <= 20 and y >= 13 and y <= 21 then
        backColors = backColors.."4"
      elseif redstone.getInput("left") and x >= 31 and x <= 42 and y >= 13 and y <= 21 then
        backColors = backColors.."4"
      else
        backColors = backColors..colors.toBlit(2^((offset+x+y)%16))
      end
    end

    monitor.setCursorPos(1,y)
    monitor.blit(spaces, frontColors, backColors)

    monitor2.setCursorPos(1,y)
    monitor2.blit(spaces, frontColors, backColors)

    --modem.callRemote("monitor_0","setCursorPos", 1, y)
    --modem.callRemote("monitor_0","blit", spaces, frontColors, backColors)
  end

  offset = offset + 1
end--]]