Cocos2D - How to make a sprite auto fire a bullet as a 10 seconds interval?

[KennyChong]

Hi All,

I am creating a game something like Plant Vs Zombies, with multiple sprites (the plants). Then,

I want them to auto-fire a bullet into incoming enemy (the zombies).

What is the best way of doing this?

I am not really good at object oriented, I tried the following (just pseudo to illustrate my approach):

in my init method of my code:

// schedule a repeating game loop
[self schedule:@selector(myGameLoop];



in myGameLoop method:

for (CCSprite thePlantSprite in thePlantSpriteArray) {

...(retrieve thePlantSprite position x and y)
[self fireBullet]; // call this method to fire a bullet from current sprite

}



I have logic problems:
1. this myGameLoop will get executed many times in a second and caused hundreds of bullets shot.
2. how can I limit to say a bullet can be shot by any sprite in every 2 seconds.

Thanks.

[missing_no]

Originally Posted by KennyChong

Hi All,

I am creating a game something like Plant Vs Zombies, with multiple sprites (the plants). Then,

I want them to auto-fire a bullet into incoming enemy (the zombies).

What is the best way of doing this?

I am not really good at object oriented, I tried the following (just pseudo to illustrate my approach):

in my init method of my code:

// schedule a repeating game loop
[self schedule:@selector(myGameLoop];



in myGameLoop method:

for (CCSprite thePlantSprite in thePlantSpriteArray) {

...(retrieve thePlantSprite position x and y)
[self fireBullet]; // call this method to fire a bullet from current sprite

}



I have logic problems:
1. this myGameLoop will get executed many times in a second and caused hundreds of bullets shot.
2. how can I limit to say a bullet can be shot by any sprite in every 2 seconds.

Thanks.

I'm sure there is a better way but I always employ an int that will count up every game loop, and I use this as a timer (so when i = 60 I know a second passed [depending on you NStimer interval])

so you can easily say

int i = 0;

-(void)theGameLoop{

i ++;
...(retrieve thePlantSprite position x and y)

if(i%1000 == 0){
[self fireBullet]; // call this method to fire a bullet from current sprite
i = 0; //reset counter
}

}

[KennyChong]

Thanks missing_no for your help. Will try this approach. Cheers.

[flamingliquid]

Or you can just use:

[self schedule:@selector(myGameLoop:) interval:2];

[hm50]

I use the dt or delta time parameter passed to your update method or gameloop. If your app is set to run at 60fps, then you could just do:

 
myFloat += dt;
 
if (myFloat >= yourDelay){
   //fire bullet
   myFloat = 0;
}

Using this method is more likely to fire at the exact interval you want, because even if your app skips a frame do to low memory or whatever issue, the delta time will still indicate the time since the method was last fired.

Good Luck!!