[OpenComputers] pnt

local component = require('component')
local event = require('event')
local gpu = component.gpu
local color = 0xFF0000
local tSize = {gpu.getResolution()}

local function line(x0, y0, x1, y1)
  local dx = x1 - x0
  local dy = y1 - y0
  local d = 2 * dy - dx
  set_pixel(x0, y0)
  y = y0
  for x = x0, x1 do
    if d > 0 then
      y = y + 1
      set_pixel(x, y)
      d = d + (2 * dy - 2 * dx)
    else
      set_pixel(x, y)
      d = d + (2 * dy)
    end
  end
end

local function circle(x0, y0, radius)
  local x = radius
  local y = 0
  local d = 1 - x
  while x >= y do
    set_pixel(x + x0, y + y0)
    set_pixel(y + x0, x + y0)
    set_pixel(-x + x0, y + y0)
    set_pixel(-y + x0, x + y0)
    set_pixel(-x + x0, -y + y0)
    set_pixel(-y + x0, -x + y0)
    set_pixel(x + x0, -y + y0)
    set_pixel(y + x0, -x + y0)
    y = y + 1
    if d <= 0 then
      d = 2 * y + 1
    else
      x = x - 1
      d = 2 * (y - x) + 1
    end
  end
end

local function box(x0, y0, x1, y1)
  for x = x0, x1 do
    for y = y0, y1 do
      set_pixel(x, y)
    end
  end
end

local function clear()
  gpu.setBackground(0x000000)
  gpu.setForeground(0x000000)
  gpu.fill(1, 1, tSize[1], tSize[2], ' ')
end

local function fill_1()
  local fg, bg = 0x000000, 0x222222
  for x = 1, tSize[1], 2 do
    for y = 1, tSize[2] do
      gpu.setBackground(bg)
      gpu.setForeground(fg)
      gpu.set(x, y, '▄')
      gpu.setBackground(fg)
      gpu.setForeground(bg)
      gpu.set(x+1, y, '▄')
    end
  end
end

clear()

while 1 do
  local e = {event.pull()}
  if e[1] == 'touch' or e[1] == 'drag' or e[1] == 'drop' then
    local pixel = {gpu.get(e[3], e[4])}
    if e[5] == 0 then
      gpu.setForeground(color)
      gpu.setBackground(pixel[3])
      gpu.set(e[3], e[4], '▄')
    elseif e[5] == 1 then
      gpu.setForeground(pixel[2])
      gpu.setBackground(color)
      gpu.set(e[3], e[4], '▄')
    end
  end
end