Swarming behaviour in Codea

Formation

--# Main
-- Formation

function setup()
    displayMode(FULLSCREEN)
    physics.gravity(0,0)
    touches = {}
    items = {}
    ships = {}
    for i=0,10 do
        local s = Ship {pos=vec2(0,50*i-400)}
        table.insert(ships, 1, s)
    end
    font("Futura-CondensedExtraBold")
end

function draw()
    background(83, 98, 125, 255)
    pushMatrix()
    translate(WIDTH/2,HEIGHT/2)   
    for i,s in ipairs(ships) do
        s:draw()
        if not isAlive(s) then table.remove(ships,i) end
    end
    for i,s in ipairs(items) do
        s:draw()
        if not isAlive(s) then table.remove(items,i) end
    end
    popMatrix()
    fill(255, 255, 255, 255)
    text("FIRE", 50,50)
end
function isAlive(s)
    if s.ttl and ElapsedTime > s.ttl then
        s:destroy()
    else
        return true
    end
end

function touched(touch)
    touches[touch.id] = touch
    local i,ti, tv = 1, 1, {}
    for id,v in pairs(touches) do
        if id == touch.id then i=ti end
        table.insert(tv, v)
        ti = ti + 1
    end
    local step = #tv
    
    -- check if button press
    if touch.state == BEGAN and touch.y < 100 then
        i,step=1,1
    end
    
    if #ships >= i then
        ships[i]:touched(touch, function()
            i = i + step
            return ships[i]
        end)
    end
    if touch.state == ENDED or touch.state == CANCELLED then
        touches[touch.id] = nil
    end
end

function collide(c)
    if c.state ~= BEGAN then return end
    local b = c.bodyA.info.bullet or c.bodyB.info.bullet
    local s = c.bodyA.info.ship or c.bodyB.info.ship
    if b then
        b.ttl = ElapsedTime-1
        if s then s.ttl = ElapsedTime+.2 end        
    end
    Explosion(c.position, 15)
end

--# Item
Item = class()

function Item:getDir()
    return vec2(0,1):rotate(math.rad(-self.body.angle))
end
function Item:setDir(dir)
    self.body.angle = math.deg(dir:angleBetween(vec2(0,1)))
end
function Item:destroy()
    self.body:destroy()
    self.body = nil
end

--# Ship
Ship = class(Item)

function Ship:init(params)
    self.id = params.id
    self.m = mesh()
    self.m.texture =("Tyrian Remastered:Ship B")
    self.m:addRect(0,0,21,27)
    self.body = physics.body(CIRCLE, 18)
    self.body.position = params.pos
    self.body.angularDamping = 4
    self.body.linearDamping = 4
    self.body.info = {ship=self}   
    self.tq = {}
end

function Ship:fire()
    Bullet(self)
end

function Ship:draw()
    pushMatrix()    
    translate(self.body.x, self.body.y)
    rotate(-self.body.angle)
    self.m:draw()
    popMatrix()
    
    if self.ttl then
        local d = 10
        local p = self.body.position +
                  vec2(math.random(-d,d),math.random(-d,d))
        Explosion(p, math.random(10,50))
    end
    
    if self.child and #self.tq>0 then
        local touch, time, childIter = unpack(self.tq[1])
        if ElapsedTime > time+.05 then
            table.remove(self.tq, 1)
            self.child:touched(touch, childIter)
        end
    end
end

function Ship:touched(touch, childIter)
    if not self.body then return end
    if touch.state == BEGAN then
        if touch.x < 100 and touch.y < 100 then self:fire() end
    end
    
    if touch.state == MOVING then
        local dv = vec2(touch.deltaX, touch.deltaY)
        local rv = math.random(1, 1.8)
        self.body.linearVelocity = (dv*50*rv)
        if dv:len() > 1 then
            self:setDir((self:getDir() + dv:normalize()*2):normalize())
        end
    end
    self.child = childIter()
    if self.child then
        table.insert(self.tq, {touch, ElapsedTime, childIter})
    end
end

function Ship:moving()
    return #self.tq>0
end

--# Bullet
Bullet = class(Item)

function Bullet:init(ship)
    self.m = mesh()
    self.m.texture =("Tyrian Remastered:Energy Orb 1")
    self.m:addRect(0,0,20,20)
    self.body = physics.body(CIRCLE, 8)
    local dir = ship:getDir()
    local p = vec2(ship.body.x, ship.body.y)+dir*28
    self.body.x, self.body.y = p.x, p.y
    self.body:applyForce(dir*400)
    self.body.bullet = true
    self.ttl = ElapsedTime+1
    table.insert(items, self)
    self.body.info = {bullet=self}
end

function Bullet:draw()
    pushMatrix()
    translate(self.body.x, self.body.y)
    scale(self.ttl-ElapsedTime)
    self.m:draw()
    popMatrix()
end


--# Explosion
Explosion = class(Item)

function Explosion:init(pos, size, ttl)
    size = size or 30
    self.m = mesh()
    self.m.texture = ("Tyrian Remastered:Explosion Huge")
    self.m:addRect(pos.x,pos.y,size,size)
    self.ttl = ElapsedTime+(ttl or .2)
    table.insert(items, self)
end

function Explosion:draw()
    pushMatrix()
    local t = (self.ttl - ElapsedTime)*4
    self.m:setColors(255,255,255,255*t)
    self.m:draw()
    popMatrix()
end
function Explosion:destroy() end