Filled Circle Generator

local sin45 = 0.70710678118

function max(tab)
  local n = 0
  for k,v in pairs(tab) do
    if v>n then
      n=v
    end
  end
  return n
end

function getSlice(r)
  local cap = r*sin45
  local rs = r^2

  local ptab = {}

  for i=cap,r,0.1 do
    local val = math.sqrt(rs - i^2)
    if not ptab[i] then
      ptab[i] = val
    elseif val > ptab[i] then
      ptab[i] = val
    end
  end
  return ptab
end

function getQuarter(r)
  local slice = getSlice(r)

  local ptab = {}

  for k,v in pairs(slice) do
    ptab[k]=v
    ptab[v]=k
  end
  return ptab
end

function getHalf(r)
  local quarter = getQuarter(r)

  local ptab = {}

  for k,v in pairs(quarter) do
    ptab[k]=v
    ptab[-k]=v
  end
  return ptab
end

function drawCircle(ptab,ofx,ofy,sc)
  term.setBackgroundColor(colors.white)
  for k,v in pairs(ptab) do
    local cx = 0
    local cy = sc and k*(2/3) or k
    cy = math.floor(cy)
    term.setCursorPos(cx+ofx,cy+ofy)
    term.write(string.rep(" ",v))
    term.setCursorPos(ofx-v+1,cy+ofy)
    term.write(string.rep(" ",v))
  end
  local len = max(ptab)
  --if len>10 then len = len + 1 end
  term.setCursorPos(ofx-len+1,ofy-1)
  term.write(string.rep(" ",len*2-1))
  term.setCursorPos(ofx-len+1,ofy)
  term.write(string.rep(" ",len*2-1))
  term.setBackgroundColor(colors.black)
end

local tArgs = {...}

local rz = 5
local scc = false
if tArgs[1] and tonumber(tArgs[1]) then
  rz = tArgs[1]
end
if tArgs[2] then
  scc=tArgs[2]
end
local tx,ty = term.getSize()
drawCircle(getHalf(rz),math.floor(tx/2)+1,math.floor(ty/2)+1,scc)
os.pullEvent()
term.clear()
term.setCursorPos(1,1)