Question about particles system

Esc · December 2014

Hello all,
after lurking for a while, here it goes a question...
I'm using @GregBug particles system and it works just fine when I show a single emitter, but I don't know how to use it in a game where many emitters are working at the same time, ie: in a game where you shoot enemies and many explosions are displayed on screen at the same time. I've tried to create an array with as many emitters I think will be on screen at the same time, and before doing an emitter:setPosition(x,y) and emitter:start() I go through the array and check if not arrayfx[n]:started() but it doesn't work very well. Am I approaching this in the wrong way ?

seppsepp · December 2014

but it doesn't work very well

Don't get me wrong - I don't want to appear unfriendly - , but what exactly does this ^^ statement mean

?

pie · December 2014

Another approach could be to assign one or more emitters to your enemy class, and start them only on certain conditions (ie. enemy.hit = true, or enemy.hp<1)

Esc · December 2014

Ok, so I've tried @pie approach and it's working.
I was having the problem of assigning the emitter to self. It should be to stage instead.
In the ball class, the line : self.emitter = CEmitter.new(0,0,0,stage)

 
menu = Core.class(Sprite)
 
wi = application:getContentWidth()
he = application:getContentHeight()
 
function menu:init()
	application:setBackgroundColor(0x000000)
	ball_list = {}
	for i=1,5 do
		local b = ball.new()
		ball_list[i] = b	
		self:addChild(ball_list[i])
	end	
	self:addEventListener(Event.ENTER_FRAME, self.onEnterFrame, self)
end
 
 
function menu:onEnterFrame()
 
	for i=1,#ball_list do
		ball_list[i]:update()		
 
	end
end	
 
-------------------------------------------------------
 
ball = Core.class(Sprite)
 
function ball:init()
	ballbmp = Bitmap.new(Texture.new("ball3.png",true))
	ballbmp:setAnchorPoint(.5,.5)
 
	self:addChild(ballbmp)
 
	self.posX = wi/2
	self.posY = he/2
	self.speedX = math.random(-5,5)
	self.speedY = math.random(-5,5)
	self.hitR,self.hitL,self.hitU,self.hitD = false,false,false,false
 
	local sparklesGFX = Texture.new("ball3.png")
	sparkles = CParticles.new(sparklesGFX, 10, .2, 0, "add")
	sparkles:setSize(0.5, 1)
	sparkles:setDirection(0,360)
	sparkles:setSpeed(140, 255)
	sparkles:setAlpha(255)
	sparkles:setAlphaMorphIn(255, 0.1)
	sparkles:setAlphaMorphOut(0, 0.2)
 
	sparkles:setColor(50,50,50, 255, 255, 255)
	sparkles:setLoopMode(1)
 
	self.emitter = CEmitter.new(0,0,0,stage)
	self.emitter:assignParticles(sparkles)
 
end
 
 
function ball:update()
	self:setPosition(self.posX,self.posY)
	self.posX = self.posX + self.speedX
	self.posY = self.posY + self.speedY
 
 
	if self.posY < self:getWidth()/2 then
		self.hitU = true
		--self.posY = self:getWidth()/2
		self.speedY = self.speedY * -1
	end
	if self.posX < self:getWidth()/2 then
		self.hitL = true
		--self.posX = 0
		self.speedX = self.speedX * -1
	end	
	if self.posX > wi-self:getWidth()/2 then
		self.hitR = true
		--self.posX = wi
		self.speedX = self.speedX * -1
	end
	if self.posY > he-self:getWidth()/2 then
		self.hitD = true
		--self.posY = he
		self.speedY = self.speedY * -1
	end
 
	if self.hitU then		
			--print("I")
			self.emitter:setPosition(self.posX, self.posY - self:getWidth()/2)
			self.emitter:start()			
			self.hitU = false
	end
	if self.hitL then		
			--print("I")
			self.emitter:setPosition(self.posX - self:getWidth()/2, self.posY )
			self.emitter:start()			
			self.hitL = false
	end
	if self.hitR then					
			self.emitter:setPosition(self.posX + self:getWidth()/2, self.posY )
			self.emitter:start()			
			self.hitR = false
	end
	if self.hitD then					
			self.emitter:setPosition(self.posX, self.posY + self:getWidth()/2 )
			self.emitter:start()			
			self.hitD = false
	end
end

pie · December 2014

@Esc in my experience TNT emitters can't be local, I suppose the same applies if these are defined as properties of a "local parent" (self.emitter, in local b = ball.new() ). I can't explain you why, since I am not sure I understood it completely..

I'm sorry I don't have time now to put a dummy project together, try this (not tested, could be worthless... :-\" ):

 
function menu:init()
	application:setBackgroundColor(0x000000)
	ball_list = {}
 
	for i=1,5 do
		ball_list[i] = ball.new()
		self:addChild(ball_list[i])
	end	
	self:addEventListener(Event.ENTER_FRAME, self.onEnterFrame, self)
end
 
--and in ball.init
--self.emitter = CEmitter.new(0,0,0,self)
 
--maybe you should also check who is parent to menu instance

Just to say, my emitters are created with "self" as 4th parameter

P.s.
I would try to avoid continuous onEnterFrame check: I don't know what do you have in mind, this could be right or wrong depending on your specific needs and situation:

if you dispatch a "personalized" event to your ball for every hit it gets, you just have to update the balls who need it instead of checking them all 30 times per second. If you have many balls this could save a lot of cpu load.

Another "easier" (and maybe "lighter") way could be to do something like:

function menu:updateBall(ball_ID)
	ball_list[ball_ID]:update()
end

hope this helps!

Esc · December 2014

Thank you @pie,
tried assigning directly ball_list[i] = ball.new() and works just fine as well. No improvements saving memory though.

About the onEnterFrame(), in my setup the balls are moving constantly and checking for a collision with the edges of the screen... I don't understand the how to dispatch a personalized event on hit without prior checking for the hit.

pie · December 2014

@Esc My mistake, I focused on the emitter part and didn't look to all the remaining code.

Howdy, Stranger!

Categories

In this Discussion

Top Posters

Question about particles system

Comments

Howdy, Stranger!

Quick Links

Categories

In this Discussion

Top Posters

Question about particles system

Comments