cocos2d for iPhone

A fast, easy to use, free, and community supported 2D game engine

1. 

   cando
   Member

   Hi guys,
   Just wanted to ask a quick question. I was wondering if this is the right way or not.

   I am trying to create random movement of a sprite in a screen. To do this I call "startRandomMovement" which creates an action and recursively calls itself. IS it ok as I will be creating a lot of actions in runtime?

   [code]
   -(void) startRandomMovement{
   int xPosition = rand() % 480;
   int yPosition = rand() % 320;
   NSLog(@"xPosition: %i, yPosition: %i", xPosition, yPosition);
   id action = [Sequence actions:
   [MoveBy actionWithDuration:2 position:ccp(xPosition,yPosition)],
   [CallFunc actionWithTarget:self selector:@selector(startRandomMovement)],
   nil];
   [self runAction:action];
   }
   [/code]

   One more quick question. The xPosition and yPosition seems to take the sprite off the screen after some moves. The move action seems to move the sprite relative to its position rather then the actual x,y position of the screen. How do I keep the sprite in the screen boundaries?

   Thanks for the help!

   Posted 2 years ago #
2. 

   imrank1
   Member

   I do something like what you have. But the function does not call itself recursively. I simply have a scheduled timer call it over and over again. Not sure if this is the best way to do randomn movement though.

   Posted 2 years ago #
3. 

   pabloruiz55
   Member

   I think that calling a recursive function will cause you slowdows... you would be better of scheduling the action like imranks1 says...

   Regarding the movement behaviour you are calling moveBy which moves the sprite by the amount of pixels you want... you should use moveTo to achieve the desired effect.

   Posted 2 years ago #
4. 

   cando
   Member

   @pabloruiz55 Great! Thanks for the fast response! :) moveTo solved the movement issue.

   I want to point out that what I am doing is same as what imrank1 has done, because the callback calls itself only after completing the moveTo action. What could be a problem in both of the implementation is that we are creating action at run time. Creating action might be a heavy task for cocos so if I add a lot of sprite it might slow things down.

   Posted 2 years ago #
5. 

   crmagicxxx
   Member

   @cando

   I am not sure what you're doing and what imrank1 suggested you is the same thing. Someone who knows Cocos2d core better, may answer if such an action which calls itself is ever ended actually? You have sequence of one action of 2 seconds and callfunc, and all should end up briefly after 2 seconds, but I am just not sure that action ends at all in the way you made it.

   Simple thing to check is retain count on that scene, or number of children (if actions are considered as children of the scene, not sure about that also because I am not on Mac).

   Another thing you can try is to use ActionManager instead of running action directly on node, so you can always check the number of actions per node, so you will see if it grows over time or not...

   More clear way, and what I am doing also, is what imrank1 suggested

   Posted 2 years ago #
6. 

   Clain
   Member

   @crmagicxxx :

   You have sequence of one action of 2 seconds and callfunc, and all should end up briefly after 2 seconds, but I am just not sure that action ends at all in the way you made it.

   The action does end after the CallFunc callback has been made. So basically, the second action of sequence 1 (the CallFunc) creates another sequence (say sequence 2) and starts running it. And right after that, sequence 1 ends and is removed from the ActionManager. Sequence 2 is still running. It's like a RepeatForever action, but done manually.

   (if actions are considered as children of the scene, ...)

   You can't say that because Actions are not Nodes. An action can never a child of a scene. But it's possible that an action retains a scene. When you do [self runAction:action];, this will add action to the ActionManager which will retain self until the action is done.

   @cando :

   Creating action might be a heavy task for cocos so if I add a lot of sprite it might slow things down.

   I remember someone on this forum saying you should reuse your actions instead of creating new ones every time. But you can't do that since you have random numbers. What you could try is, when you're about to call startRandomMovement on all of your sprites, don't do it all at once. Say the actions last 2 seconds and you have 20 sprites. Do something like [spriteX startRandomMovement] every 0.1 s. This way, instead of having 20 actions recreated at the same time every 2s (which could cause slowdowns), you'd have one new action recreated every 0.1 s. The load would be balanced and if the cause of the slowdown(s) is really the creation of new actions, that should prevent it. Since I never tried it, I can't say for sure if this trick would work. But that's what I'd try though.

   Posted 2 years ago #
7. 

   cando
   Member

   Hi Clain,
   Thanks a lot for you awesome insight. I really appreciate all of you for being soo helpful :)
   I initialized around 50 sprites with my original code and everything seems to run smoothly. I am getting a fps of 40-59
   I guess as long as the actions are deleted by cocos after the animation finishes, I wont have any memory issues. Since I am sending the sprites in a random sequence they are not all changing direction at a time so this avoids the cpu clogging issue...

   Thanks a lot all of you!

   Posted 2 years ago #

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