keiki_example

local keiki = require("keiki")

--[[
    * a usual (slow) game's code goes something like this:
    *
    * list = keiki.new(100)
    * while wait() do
    *  list:iter(list_update_function)
    * end
--]]


--> a list of bullets. each has a 2D position, speed, and angle.
local list_bullet = keiki.new(512,function(may,i,o)
    o.position = Vector2.new()
    o.speed = 0
    o.angle = 0
end)

--> loops through all bullets in the list, to move them all at once.
local function bullet_update(list,i,o)
    -- if the current object is dead, then don't update it!
    if not o.dead then
        local angle = o.angle
        local speed = o.speed
        local velocity = speed * Vector2.new(math.cos(angle),math.sin(angle))

        o.position = o.position + velocity
    end
end

--> creates a new bullet in the list.
local function bullet_add(pos,spd,ang)
    -- > 0 is the first argument, since there aren't
    -- >>any other types of bullets.
    list_bullet:add(0,function(list,i,o)
        o.position = pos
        o.speed = spd
        o.angle = ang
    end)
end

--> now let's actually shoot some damn bullets for once
local timer = 0
game:GetService("RunService").Heartbeat:Connect(function(dt)
    -- every 0.5 seconds, add a new bullet.
    if timer>=0.5 then
        timer = 0
        bullet_add( Vector2.new(0,0),4,math.rad(timer*10) )
    end
    -- now, update the bullets.
    list_bullet:iter( bullet_update )
    -- wait and add to the timer
    timer = timer + dt
end)