getRandromInCircle.lua

function roundm(n, m) return math.floor(((n + m - 1)/m))*m end

-- Now we can change the returned value from getRandomPointInCircle to:

function getRandomPointInCircle(radius)
  local t = 2*math.pi*math.random()
  local u = math.random()+math.random()
  local r = nil
  if u > 1 then r = 2-u else r = u end
  return roundm(radius*r*math.cos(t), tile_size), 
         roundm(radius*r*math.sin(t), tile_size)
end


function getRandomPointInEllipse(ellipse_width, ellipse_height)
  local t = 2*math.pi*math.random()
  local u = math.random()+math.random()
  local r = nil
  if u > 1 then r = 2-u else r = u end
  return roundm(ellipse_width*r*math.cos(t)/2, tile_size), 
         roundm(ellipse_height*r*math.sin(t)/2, tile_size)
end

From: http://www.gamasutra.com/blogs/AAdonaac/20150903/252889/Procedural_Dungeon_Generation_Algorithm.php

How it works: http://stackoverflow.com/questions/5837572/generate-a-random-point-within-a-circle-uniformly

https://github.com/Yonaba/delaunay