cocos2d for iPhone

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

1. 

   Korigame
   Member

   Hi,
   I had it working once, now I can't figure it out again: I am trying to move sprites that are contained within a single NSMutableArray manually, updating the sprites position in my tick function:
   

   // Move Pieces
   	for(CCSprite *curSprite in _movableObjects) {
   		if(curSprite.tag == 10) {
   			if(_now - _pieceLastMoved >= _pieceSpeed) {
   				curSprite.position = ccp(curSprite.position.x,curSprite.position.y - 1);
   				_pieceLastMoved = _now;
   			}
   		}
   	}

   This chunk is suppose to search the array "_movableObjects" for any sprites with tag of 10 and move them. It works fine for the first sprite, it moves downwards as the code suggests, but then none of the other sprites follow as they should. I know it works someway similar to this because I've done it once. I must be missing something. No matter what I try, only the first sprite likes to mock me by working properly. Thanks for your consideration :)

   Posted 1 year ago #
2. 

   developerDoug
   Member

   NSArray, NSMutableArray has this method:

   [_movableObjects makeObjectsPerformSelector:@selector(someMethod)];

   Posted 1 year ago #
3. 

   Korigame
   Member

   That's interesting. However, considering that bit of code I posted is in my tick function, shouldn't it constantly be iterating through it?

   Posted 1 year ago #
4. 

   Benihana
   Member

   Either your tags are not what you think they are (set a debug point at the if(_now... line), or after the first iteration, _pieceLastMoved is set to now, so the left side of the second if statement evaluates to 0, which is less than _pieceSpeed. What is pieceSpeed?

   Posted 1 year ago #
5. 

   Korigame
   Member

   pieceSpeed is a float number of 0.01 and controls how often the if statement is executed, I can change pieceSpeed to affect how fast the pieces move down 1 pixel, hence the name. This doesn't affect the issue I am having. But I think you are on track with suspecting that the tags might not be right. If I add an else statement after the curSprite.tag == 10, executing a break, none of the sprites move.

   Posted 1 year ago #
6. 

   Benihana
   Member

   This doesn't affect the issue I am having.

   You sure about that?

   First sprite:
   

   for(CCSprite *curSprite in _movableObjects) {
   		if(curSprite.tag == 10) {
   			if(_now - _pieceLastMoved >= _pieceSpeed) {
   				curSprite.position = ccp(curSprite.position.x,curSprite.position.y - 1);
   				_pieceLastMoved = _now;
   			}
   		}
   	}

   Second sprite:
   

   if(curSprite.tag == 10) {
   			if(_now - _now >= _pieceSpeed) {
   // _pieceLastMoved = _now from previous iteration, _now-_now = 0,
   // so left side is less than 0.01 and subsequent sprites don't get moved
   				curSprite.position = ccp(curSprite.position.x,curSprite.position.y - 1);
   				_pieceLastMoved = _now;
   			}
   		}
   	}

   Posted 1 year ago #
7. 

   Benihana
   Member

   In fact, is there a reason you're setting _pieceLastMoved to _now? Those variables don't seem related.

   Posted 1 year ago #
8. 

   Korigame
   Member

   It was my understanding that _now continues to rise, and the difference between now and pieceLastMoved is apparent based on that understanding. I hope that is clear :(. For instance, if you were to move a sprite down the screen manually, would your method be similar?

   Posted 1 year ago #
9. 

   Benihana
   Member

   _now is not changing within your loop, as the only code that is being executed during the loop is what you have written. Quite honestly I'm not sure where _now is coming from. It's not a property of any of the cocos2d classes as far as I know. There is a dt parameter that is passed to your tick method, and represents the time since tick was last called. This dt won't change for each call (or round) of tick, and so you'll have the same issue as I mentioned.

   I would probably not move the sprite manually. There are far too many advantages of CCActions to not use them instead.

   Posted 1 year ago #
10. 

    Korigame
    Member

    Thanks a lot, I think I can figure it out from here, much appreciated. The reason I wanted to move them manually was that I can change the speed mid-action, whereas if I were to use CCActions, I understand that a CCMoveTo, for instance, has a set speed and is not updated to accommodate speed changes.

    Posted 1 year ago #
11. 

    Benihana
    Member

    The reason I wanted to move them manually was that I can change the speed mid-action, whereas if I were to use CCActions, I understand that a CCMoveTo, for instance, has a set speed and is not updated to accommodate speed changes.

    You can stop the action, then create a new one with the new duration. You could also modify CCMoveTo to allow you to change speed, or create a new subclass of CCActionInterval which performs CCMoveTo s with specific speeds. There may even be code on this forum to that effect.

    Of course it's your program, and if the manual method works best for you, then by all means use it. Just wanted to make sure you understood the alternative, and that it will prevent certain possible problems in the future.

    Posted 1 year ago #
12. 

    Korigame
    Member

    Thanks for all your help Benihana, I will thank you again when I finish my game!

    Posted 1 year ago #
13. 

    Korigame
    Member

    I fixed my problem! I needed to switch things around a bit. At first I was appealing to sprite, one by one. I changed the code so that I satisfy the movement desired first, for all the sprites, then simply make those sprites that I wanted to move respond to that movement (some code will explain it more easily).

    This is updated in my tick method:

    `_totalSpeed = _totalSpeed + 0.008; //update a double variable and reference this for movement iterations by 0.008 or w/e
    if(_totalSpeed - _pieceLastMoved >= _pieceSpeed) { // satisfy the movement code first, pieceSpeed can be w/e you want

    for(Object *curSprite in _deleteObjects) { // then move those sprites that I want
    if(curSprite.tag == 10) { // Moves all objects in my array with tag 10
    curSprite.position = ccp(curSprite.position.x,curSprite.position.y + 1);
    _pieceLastMoved = _totalSpeed;
    }
    }

    }`

    Hope this helps anyone looking to move multiple sprites at the same time, manually, and inside an array.
    I wanted the code to react this way because I wanted the speeds of the objects on screen to change speed based on my player's Y-Coor. If the player is higher up on the screen, the objects move slower, making the game easier though slower pace- if the player is nearer the bottom the objects move faster but it becomes more of a challenge to avoid them.

    Posted 1 year ago #

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