cocos2d for iPhone

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

1. 

   JavaWizKid
   Member

   How can I get access to information of the CCSprite inside of an array such as x and y positions?
   This is my code at the moment and it returns the values of 0 all the time and I don't know why.

   for(int i = 0; i < 10; i++)
   {
   [bulletsBuilder addObject: [CCSprite spriteWithFile:@"bullet.png"]];
   }

   if(bulletNumber < 10)
   {
   ((CCSprite *)[bulletsBuilder objectAtIndex:bulletNumber]).position = ccp(blob.position.x, blob.position.y);
   [self addChild:((CCSprite *)[bulletsBuilder objectAtIndex:bulletNumber])];
   NSLog(@"X Position: %i", ((CCSprite *)[bulletsBuilder objectAtIndex:bulletNumber]).position.x); // Returns 0 for some reason
   NSLog(@"Y Position: %i", ((CCSprite *)[bulletsBuilder objectAtIndex:bulletNumber]).position.y); // Returns 0 for some reason
   bulletNumber++;
   }

   Thanks.

   Posted 2 years ago #
2. 

   plasticpower
   Member

   Have you tried:

   [[bulletsBuilder objectAtIndex:bulletNumber] setPosition:ccp(...,...)];
   /\ You might find that there's nothing in the array at this point and throw an exception, then you know you have some sort of an initialization issue.

   Before your NSLog method:
   CGPoint *point = [[bulletsBuilder objectAtIndex:bulletNumber] position];
   NSLog(@"...", position.x, position.y);

   Make sure you're initializing the NSMutableArray properly.
   You might have to do something like:

   CCSprite *sprite = (CCSprite*)[bulletsBuilder objectAtIndex:bulletNumber];
   /\ This is what I normally do to make life easier if you need to do stuff with objects from the array.

   Posted 2 years ago #
3. 

   JavaWizKid
   Member

   For CGPoint I get an error of: error: incompatible types in initialization

   Posted 2 years ago #
4. 

   Questor
   Member

   JavaWizKid,

   I think your NSLog format is incorrect, you are using:
   

   NSLog(@"X Position: %i", ((CCSprite *)[bulletsBuilder objectAtIndex:bulletNumber]).position.x);
   NSLog(@"Y Position: %i", ((CCSprite *)[bulletsBuilder objectAtIndex:bulletNumber]).position.y);

   but it should be something like:
   

   NSLog(@"X Position: % .2f", ((CCSprite *)[bulletsBuilder objectAtIndex:bulletNumber]).position.x);
   NSLog(@"Y Position: % .2f", ((CCSprite *)[bulletsBuilder objectAtIndex:bulletNumber]).position.y);

   Hope this helps,
   Q

   Posted 2 years ago #
5. 

   JavaWizKid
   Member

   Ahh yes that worked thanks! Why are the coordinates float variables though? How can you have say 2.32 pixels on the x axis? How do I convert them into integers?

   Posted 2 years ago #
6. 

   Codemattic
   Moderator

   intValue = (int) floatValue;

   the (int) cast is optional, but the compiler may give you warnings without it.

   Posted 2 years ago #
7. 

   Codemattic
   Moderator

   "Why are the coordinates float variables though?" You may want to scale the camera in and out - so if you zoomed in 200%, now ints can only reach every other x value. You may want to move your sprite by a fractional amount. You may want to use vector or linear or algebraic math - and thats not going to work well with ints. While you can only display pixels, your objects exist as floats. And yes a sprite displayed at 0.5,0.0 will look different than at 0.0,0.0 - opengl does antialiasing and such (you can actually turn this off and on by calling Texture's -setAliasTexParameters or -setAntiAliasTexParameters)

   Posted 2 years ago #
8. 

   JavaWizKid
   Member

   I've added this code to make the bullets move:

   for(int i = 0; i < 10; i++)
   {
   float x = ((CCSprite *)[bulletsBuilder objectAtIndex:i]).position.x;
   float y = ((CCSprite *)[bulletsBuilder objectAtIndex:i]).position.y;
   x += 5;
   [[bulletsBuilder objectAtIndex:i] setPosition:ccp(x, y)];

   if(((CCSprite *)[bulletsBuilder objectAtIndex:i]).position.x > 490)
   {
   [self removeChild:((CCSprite *)[bulletsBuilder objectAtIndex:i]) cleanup:YES];
   bulletNumber--;
   }
   }

   However when the if function is called it errors with:

   Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[NSCFArray objectAtIndex:]: index (-376( or possibly larger)) beyond bounds (10)'

   Why?

   Posted 2 years ago #
9. 

   Codemattic
   Moderator

   you run a loop from 0 to 9 for an array with 10 Sprites, but you occasionally remove a Sprite while in the middle of that loop, so now you have less than 10 Sprites in that array so you overstep its bounds.

   Posted 2 years ago #
10. 

    JavaWizKid
    Member

    How can I fix that? How do I check what has been removed and put it back?

    Posted 2 years ago #

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