cocos2d for iPhone

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

1. 

   jorgevmendoza
   Member

   Hi, like most of the people am going to start my post by saying that am kind of new to the Iphone Develop, i'd been develop apps in C# for years just a few months ago i started building a video game for the Iphone. My problem is this:

   I have a very simple game and i just add enemies that moves across the screen and you have to shoot them, the problem is that when you star adding the enemies and they are moving you see like a little jump on their movement. i'd tried several ways to move the sprites through the screen but it always shows the same behavior, here is my code, thanks to you all in advance.

   #CODE

   ..... [self schedule:@selector(update:) interval:1.5];

   - (void)update:(ccTime)dt
   {
   //addEnemies.
   CCSprite * enemy = [CCSprite spriteWithFile:@"Icon.png" rect:CGRectMake(0, 0, 65, 65)];
   enemy.position = ccp(480,300);
   [self addChild:enemy];
   id actionMove = [CCMoveTo actionWithDuration:1.5 position:ccp(0, 300)];
   id actionMoveDone = [CCCallFuncN actionWithTarget:self selector:@selector(EnemyMoveFinished:)];
   [enemy runAction:[CCSequence actions:actionMove, actionMoveDone, nil]];
   }

   -(void)EnemyMoveFinished:(id)sender
   {
   CCSprite * enemy = (CCSprite *)sender;
   [self removeChild:enemy cleanup:YES];
   }

   Posted 2 years ago #
2. 

   Bongeh
   Member

   i personally found that CCMoveTo was alittle intensive for sprites, not so much when theres only a few, but more so when you have multiple enemies. Not sure what everyone else's experiences are. I tend to only use CCMove/CCRotate etc for menu items, moving the hud in and out of the screen when the game pauses etc.

   I move all sprites on my game by litterally assigning them a new position.

   for instance my enemy sprite will have a scheduler called MoveMe:

   (use backticks for code ` )

   -(void) moveMeOn: {
   
   	[self setVisible:YES];
   	[self schedule:@selector(moveMe:) interval:0.01];
   }
   
   -(void)moveMeOff {
   
   	[self unschedule:@selector(moveMe:)];
   	[self setVisible:NO];
   
   }
   
   -(void)moveMe:(ccTime)dt {
   
   	if ([[LevelManager sharedLevelManager] isGameOn]) {
   
   		CGPoint spritePos = [self position];
   
   			spritePos.y -= [[LevelManager sharedLevelManager] gameSpeed];
   
   		self.position = spritePos;		
   
   	}
   }

   This is slightly stripped down code, gameSpeed is an int of 4, this moves the sprite in question down the screen (in portrait) very smoothly (and quite quickly).

   Obviously the disadvantages of this are you can't set a position for the sprite to move to WITH a specified time for it to take to get there, but it's worked for me.

   Hope it helps

   Posted 2 years ago #
3. 

   David994A
   Member

   I've had no problem using CCMoveTo/CCMoveBy for all of my enemies and I have a lot of them.

   Can you describe the jumping a little better? what version of cocos2d are you using?

   Also, are there any noticible changes to the FPS indicator when this "jump" occurs? How many enemies are on the screen at a given time?

   Posted 2 years ago #
4. 

   petrusali
   Member

   The code seems fine to me. R u testing on simulator or device? For me, "jumping" on simulator is normal.

   Posted 2 years ago #
5. 

   jorgevmendoza
   Member

   Wow, thanks for all the responses!

   Bongeh thanks GOD for your answer i thougth i was the only person with this issue cause i didn't find no body else with it, i'll try your solution latter today.

   David994A The "jumping" behavior is like the sprite "jumps" one or two pixels foward, the version of the cocos2d that am using is the 0.99.0-final and no, you don't see any change in the FPS, some times it happens whe there is just one enemy, some times happens when there are 3 of them.

   petrusali The "jumping" behaivor is present in the device (IpodTouch 3G with last version of Iphone OS 3.1.3) and Simulator.

   Thanks to you all for your responses.

   Posted 2 years ago #
6. 

   Blue Ether
   Member

   Like Bongeh, I never use actions for game-engine-related activities. You should really have your own custom engine for handling critical things like that, as they do need to be streamlined. I'm always shocked to find people using these actions in such a way. I'm not of the belief that they were ever intended to handle activities such as enemy movements.

   Posted 2 years ago #
7. 

   cjl
   Member

   I wouldn't init a sprite in your update method.

   Posted 2 years ago #
8. 

   David994A
   Member

   I've really had no problem using actions for enemy movements, etc

   cjil is right, you should not be creating sprites (or destroying for that matter) in your update loop. I have all of my sprites created before the game level starts

   Posted 2 years ago #
9. 

   jorgevmendoza
   Member

   Blue Ether, thanks!, but what's the point on use a game engine if it's functions doesn't work in the rigth way?, however thanks for the advice i'll create my own functions looking for the optimization of the process.

   cjl, what do you suggets to create new enemies, adding them throug update i don't need to count or control how many enemies am adding.

   David994A, what do you suggest, you create the instance of all your enemies before start the game?

   Once more Thanks to you all guys!

   Posted 2 years ago #
10. 

    cjl
    Member

    @jorgevmendoza

    From the code you posted above it's not really clear to me what your game is doing. But, in general, I think it's a better practice to initialize all your assets in an 'init' function, before you start any actions or gameplay. Create all your enemies and store them in an NSArray, or whatever you like for a collection. Update functions should be used to update the properties of you game object, things like position, visibilty, etc. I think creating ( and destroying ) lots of objects during your gameplay might be causing your problem, but that's mostly a guess.

    Posted 2 years ago #
11. 

    FBryant
    Member

    I'm always shocked to find people using these actions in such a way. I'm not of the belief that they were ever intended to handle activities such as enemy movements.
    --------------------------------------------

    Considering basically everything in cocos2d is designed for games, I'd be very suprised if a function named MoveTo wasn't designed for moving game obects.

    jorgevmendoza, always think about how often a method is called, if it's called all the time then try not to alloc/dealloc anything within it. Ofc creating your enemies beforehand can be a pain instead of just getting a new one at the time, but it's worth doing.

    For example I alloc 10+ enemies all at once in one method, but that method is only called once every 5 minutes so I don't really care about the cost.

    Posted 2 years ago #
12. 

    gaminghorror
    Member

    >>I'm always shocked to find people using these actions in such a way. I'm not of the belief that they were ever intended to handle activities such as enemy movements.<<

    I also like to quote on this simply because it's a matter of knowing where to spend your time on. If your game has at most 10 enemies on screen, the actions won't make a difference, so why not use them?

    If the game has lots of stuff going on already, plenty of enemies and their movement would require you to keep creating new actions, then i'd think about not using actions. But until i get to that point, Actions i will use.

    I wrote a small game as contractor which i desperately wanted to run at 60 fps. When i had this optimized (background PVR with GL_REPEAT, proper use of spritesheets, 16-bit textures fallback mode for 1st gen devices), i added several things like flying score display which are animated with complex sequences of actions. Since my issue was with fillrate while the CPU has very little to do i could afford using rather complex actions and still achieve 60 fps.

    On Topic:
    i would investigate where the jumps are coming from. First thing: try it with one enemy, same behavior? If there are still hickups i suspect the problem may not even be related. Reboot the iPhone, build a release version, deploy it on the device and disconnect it before playing to make sure the debugger isn't attached. A common cause for hickups is the debugger printing log lines to the console, or using a debug build to make judgement calls about performance (mostly pointless).

    Posted 2 years ago #
13. 

    crmagicxxx
    Member

    Based on your code, I think "jumps" are due to removing and "cleaning up" sprites. From my experience, better and faster approach is hiding/re-using sprites

    Posted 2 years ago #

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