generator.js

var screen = require("screen")
var point = require("screen/point")

var center = point()
var world = screen(center, 800, 600)

var gen = generator(world, {
    tick: 1000
    , density: 3
})

/*
    Generator emits items if the density on the current screen
    is less then the set value.

    i.e. if there are less then 3 points in the world near 
    the center it will emit new items to be created.

    It does so once every tick until the density is matched
*/
gen.on("item", function (pos) {
    // pos.x, pos.y
})