Party.lua

Party = class()

function Party:init(s)
	self.x=WIDTH/2
	self.y=HEIGHT/2
	self.maxparts = 100
	self.parts = {}
	function self.draw()
		local k,v
		for k,v in pairs(self.parts) do
			if (v.draw) then v.draw() end
		end
	end
	function self.update()
		if (# self.parts < self.maxparts) then self.emit() end
		local n,k,v = {}
		for k,v in pairs(self.parts) do
			if (not v.dead()) then
				if (v.update) then v.update() end
				table.insert(n, v)
			end
		end
		self.parts = n
	end
	function self.emit()
		local p = Party()
		p.parent = self
		p.x = p.parent.x + math.random()*15-8
		p.y = p.parent.y + math.random()*15-8
		p.maxparts = 0 -- not an emitter
		function p.draw() rect(p.x, p.y, p.scale, p.scale) end
		function p.update()
			local dx = (p.x - p.parent.x)
			local dy = (p.y - p.parent.y)
			p.x = p.x + dx*0.02
			p.y = p.y + dy*0.02
			p.scale = math.max(math.abs(dx), math.abs(dy))/70 +1
		end
		function p.dead() return Party:oob(p) end
		table.insert(self.parts, p)
	end
	if (s) then -- passed a hash
	end
end

function Party:oob(p)
	if (p.x) then
		if (p.x < 0) then return true end
		if (p.x > WIDTH) then return true end
	end
	if (p.y) then
		if (p.y < 0) then return true end
		if (p.y > HEIGHT) then return true end
	end
	return false
end