Problem giving objects different amount of lives, collisiondetection

cocos2d for iPhone » Programming » physics

Problem giving objects different amount of lives, collisiondetection

(15 posts) (4 voices)

Started 1 year ago by MrLucky
Latest reply from mobilebros

Tags:

MrLucky
Member

Hi, i have been searching this forum without finding a question to this problem.
I am developing a game, and hopefully different enemies will have different amount of lives.
With my code so far, the ones that are supposed to have 2 lives, have randomly 1 or 2 lives,
the ones that should have 3 lives have randomly 1,2 or 3 lives,
and i can't make it right for some reason. Please take a look at the methods and see if you can figure
out what is wrong. Thx =)

This is my create method:

-(id) makeSpaceRockX: (cpSpace *)space x:(float) x y:(float)y hitted:(int) hitted
{
RockSprite = [[Sprite spriteWithFile:@"EvilMonkey2.png"] retain];

hit = hitted;

cpVect verts[] = {
cpv(-35,-35),
cpv(-35, 35),
cpv(35, 35),
cpv(35,-35),
};

RockBody = cpBodyNew(200.0f, INFINITY);
RockBody->p = cpv(x, y);
RockBody->v = cpv(0, 0);

cpSpaceAddBody(space, RockBody);

rockShape = cpPolyShapeNew(RockBody, 4, verts, cpvzero);
rockShape->e = 0.9f; rockShape->u = 0.9f;
rockShape->data = RockSprite;
rockShape->collision_type = 4;
cpSpaceAddShape(space, rockShape);

ready = YES;
return self;
}

The two different collision methods, one removing the bullet, and one removing the bullet and the falling object:

static int bulletCollision(cpShape *a, cpShape *b, cpContact *contacts, int numContacts, cpFloat normal_coef, void *data)
{
GameNode *game = (GameNode*) data;
[game createExplosionX:b->body->p.x + 10 y:b->body->p.y + 10];
a->body->p = cpv(-800,-800);
b->body->p = cpv(-800,-800);
return 0;
}
static int bulletCollision2(cpShape *a, cpShape *b, cpContact *contacts, int numContacts, cpFloat normal_coef, void *data)
{
GameNode *game = (GameNode*) data;
[game createExplosionX:b->body->p.x + 10 y:b->body->p.y + 10];
b->body->p = cpv(-800,-800);
return 0;
}

This is how i initialize them:

for(int i = 0; i < 3; i++) {
Rock2 *r = [[Rock2 alloc] makeSpaceRockX: space x:160 y:550 hitted:0];
[self addChild: r.getSprite];
[rocks2 addObject: r];
[r release];
}

These are my collision setup, 1 is the bullet, 3 and 4 is the falling object depending on what collision to use:

cpSpaceAddCollisionPairFunc(space, 4, 1, &bulletCollision2, self);
cpSpaceAddCollisionPairFunc(space, 3, 1, &bulletCollision, self);

And this is my update-method, that should decide how many lives each object should have:

-(void) updateRocks2
{
if(rock2go) {
for(Rock2 *r in rocks2) {
if([r getHit] == 4) {
[r setHit:1];
r.getShape->collision_type = 4;
}
if([r getHit] == 0) {
r.getShape->collision_type = 4;
}
if([r getHit] < 2) {
r.getShape->collision_type = 4;
}
if([r getHit] == 2) {
r.getShape->collision_type = 3;
}
if([r getHit] > 3) {
r.getShape->collision_type = 4;
[r setHit:1];
}
for(Bullet *b in bullets) {
if((([b getY] <= [r getY] + 40) && ([b getY] >= [r getY]-55)) &&
(([b getX] <= [r getX] + 25) && ([b getX] >= [r getX]-25))) {
[r setHit:[r getHit]+1];
}
}
if([r getY] <= -600) {
if(liv >0) score += 10;
[r resetPosition];
[r setReady: YES];
break;
}
else if([r getY] <= 0) {
if(liv >0) score -= 20;
[r resetPosition];
[r setReady: YES];
break;
}
}
}
}

Posted 1 year ago #
MrLucky
Member

If anyone has any better solution to giving objects a specific amount of lives, that would also be very helpful

Posted 1 year ago #
mobilebros
Moderator

Why aren't you just keeping a counter in your RockSprite, seems like this would get rid of a ton of code. In your collision handler just subtract one from your counter, when it's zero then its dead.

Posted 1 year ago #
zenkimoto
Member

I agree with mobilebros. Just keep the hit point information in RockSprite. In addition, are you using Chipmunk >= 5.1? What happens when you use cpSpaceAddCollisionPairFunc() is that it keeps being called during the entire duration of the collision. You might want to be using cpSpaceAddCollisionHandler() instead. I would suggest looking into the Begin event. And in the begin event, deduct one from the hit points from RockSprite.

Check out the example:

http://code.google.com/p/chipmunk-physics/wiki/CallbackSystem

Hope this helps.

Posted 1 year ago #
MrLucky
Member

How is it possible to keep a counter in my RockSprite? Do you have an example?
And yes, i use chipmunk. Thx for the help guys, it's very appreciated =)

Posted 1 year ago #

zenkimoto
Member

@MrLucky

You need to inherit from CCSprite.

@interface RockSprite : CCSprite {
   int hitPoints;
}
@property (nonatomic) int hitPoints;
@end

@implementation RockSprite
@synthesize hitPoints;
@end

Hope this helps.

Posted 1 year ago #

MrLucky
Member

Thx, i will try that =)

Posted 1 year ago #
MrLucky
Member

i can't make it work for some reason. I am pretty new to objective c, and not everything
is that easy for me to understand. Is there somehow you can try to change my code above,
so that it properly takes in a counter in the RockSprite or the class? I only get errors when i try
to work in your example.

Posted 1 year ago #
mobilebros
Moderator
Yeah... it looks like you're doing a few sketchy things, this line in particular looks scary to me:
```
Rock2 *r = [[Rock2 alloc] makeSpaceRockX: space x:160 y:550 hitted:0];
```
In particular because you are alloc'ing a Rock2... but then calling makeSpaceRockX off of it which returns a Sprite... which is not a Rock2 type... crash?

In zenkimoto's example you'd want to create a rock sprite by doing something like this:
```
RockSprite rock = [RockSprite spriteWithFile:@"EvilMonkey2.png"];
rock.hitPoints = 3;
```
Posted 1 year ago #
Bongeh
Member
Just to add to what mobilebros said you could use this extra snippet of code to generate random lives between 1 and 3
```
RockSprite rock = [RockSprite spriteWithFile:@"EvilMonkey2.png"];
int hitPoints = 1 + random()%3;
rock.hitPoints = hitPoints;
```
although, i dont like using the . method myself, i'd rather give rocksprite a setter and getter property and use something like

[rock setHitPoints:hitPoints];

to set the value, but thats just personal preference
Posted 1 year ago #

zenkimoto
Member

@MrLucky

Mobilebros is right. The other alternative is to initialize it in the constructor.

@implementation RockSprite
@synthesize hitPoints;
-(id) init {
   if ((self = [super init])) {
      hitPoints = 3;
      // Or use random()
   }
}
@end

Then, you would just declare it as usual.

RockSprite rock = [RockSprite spriteWithFile:@"EvilMonkey2.png"];

Posted 1 year ago #

MrLucky
Member

Ok, thx, that made sence =) i am a computer engineer student, but our study only uses java, so i have problems
understanding pointers, and when to use "." and when to use "->" and so on.... objective c i kinda confusing :P

@mobilebros

Actually, it doesn't crash, the game runs pretty smooth, and is almost finished :)
the code is ugly and confusing, though.
This is the only problem i have left.

I'll try to change the code into what you guys have posted, and hopefully it will work :)

Posted 1 year ago #
mobilebros
Moderator

@MrLucky

Yeah objective-c takes a little getting used to for sure, even though your game is running fine, that statement still sets off alarm bells for me, you may just be leaking memory which isn't too big a deal but....

Heres what seems wrong about it to me:

You're alloc'ing, meaning you just created a chunk of memory and then you are calling a method off of that... but instead of returning self in that function you return a Sprite which you then hold on to.... however you lost any reference to the thing you just alloc'd! Mem Leak! Anyway, the choice is yours.

Posted 1 year ago #
MrLucky
Member

Memory leak is absolutely a problem. Is there a way to check the amount of memory leak produced by the application?
Anyways, i will for sure see if i can change that method and stop the leak.

Thx for the help, it is very appreciated =)

Posted 1 year ago #
mobilebros
Moderator

Check out Instruments, installed with xcode. It has a bunch of ways to profile your app, takes a little getting used to but ultimately worth it.

Posted 1 year ago #

RSS feed for this topic

Reply

You must log in to post.