error in recursive function « cocos2d for iPhone

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error in recursive function

(9 posts) (5 voices)

Started 2 years ago by gametest
Latest reply from gametest

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gametest
Member

Hello,
In my game i am generating power at some interval. I am setting position of power by one function named "setXYPower".
I have some obstacles in the screen. The generated power and any of obstacles must not be at the same position.

-(void)setXYPower
{

bool flag = FALSE;

int x = 30 + arc4random() % (460-30+1);
int y = 20 + arc4random() % (300-20+1);

CGRect rect1 = rectangle of sprite (power);
CGRect rect2;

for(obstacles *t in arrObstacles)
{
rect2 = rectangle of obstacle;
if(CGRectIntersectsRect(rect1, rect2) == TRUE)
{
flag = FALSE;
break;
}
}

if(flag == TRUE)
{
Set position of power sprite //powerFix.position = cpv(x,y);
}
else
{
[self setXYPower];
}
}

Now, my problem is in some level when there are many obstacles & [self setXYPower] call more then one error (GDB:Program loaded)comes.

New window (Debugger) is open and following line is displayed.

loading 24959 stack frame... (1,2,... %)

Thanks in advance.

Posted 2 years ago #
Codemattic
Moderator

well it seems like flag is never set TRUE so -setXYPower calls -setXYPower which calls -setXYPower, etc... until... boom.

btw in objective c a BOOL datatype has a value of YES or NO.

Posted 2 years ago #
pabloruiz55
Member

From what i see you are never setting flag to YES,thus the function keeps calling itself until it crashes...

Posted 2 years ago #
Joao Caxaria
Member

Yeah, I would say the flag should be initialized with bool flag = TRUE;

btw, and a bit off the original question, how would you guys do this function: Recursive or iterative?

The only thing I can think of from the top of my mind to be able to do it recursive is to allow several threads to share the work.. Like it is, it will just add up to the call stack, not helping performance, right?

Posted 2 years ago #
Codemattic
Moderator

JC, I agree, I dont think recursive is the way to go for this.

Posted 2 years ago #
riq
Key Master

[moved to everything else]

Posted 2 years ago #
gametest
Member

oops , I made mistake in posting the question I wrote BOOL flag = TRUE; in declaration. So, flag is set to TRUE at first & in some condition it will be FALSE.

I think function call itself is called recursion. in this case function calls itself. so.....

Pls help me to solve this problem.

Posted 2 years ago #
pabloruiz55
Member
I think the problem still remains even if you initialy set the flag to true...

when you enter here:
```
for(obstacles *t in arrObstacles)
{
rect2 = rectangle of obstacle;
if(CGRectIntersectsRect(rect1, rect2) == TRUE)
{
flag = FALSE;
break;
}
}
```
if at some point flag becomes false, the function will call itself and in the next call nothing will change that makes the flag not to change to false...

I mean... if the 2 rectangles intersect, the function will be called again, the second time, nothing has changed, so it will be called again, and so on...

I think that you should be able to solve this in another way...

What i would do is to store all the obstacle's positions in an array and then place the object in a different position than those in the array.
Posted 2 years ago #
gametest
Member

Every time i am generating new random numbers x and y so new rect will be generated when function calls. So, if that new rectangle made by (new x and y) intersect with any of obstacles's rectangle then only function call itself otherwise power set to that x & y position.

I think by taking array of obstacle's position I have to do the same thing.

Posted 2 years ago #

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