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protocol

(8 posts) (4 voices)

Started 2 years ago by stu
Latest reply from stu

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stu
Member

Suppose I have a Car object that consists of an engine, window, body, car wheels, etc. as instance variables. If I would like to give this car the ability to "disappear" or fade from the screen, then I might use the FadeIn/FadeOut actions.

Presently my car is a cocosnode, my window, wheels, and car body are all sprites. I would like to be able to be able to do something like
[carInstance do: [FadeOut actionWithDuration:3]];
and have all the components of the car fade together. I would like to avoid a loop that runs through each component and fades them one at a time.

My question is I'm not sure how to implement this. Is it enough that the Car class (type CocosNode) adopt the <CocosNodeOpacity> protocol? Do all the instance variables that are displayed need to adopt it as well? Do I need to implement methods setOpacity and Opacity for each object that adopts <CocosNodeOpacity>? Should I add each instance variable (component) as a child of the car?

Any insight is appreciated.

Posted 2 years ago #
stu
Member

By the way the title of this thread was supposed to be <CocosNodeOpacity> protocol but it looks like the angle brackets ate up the word.

Posted 2 years ago #
pabloruiz55
Member

Hi! what i do is the following:

mySprite = [Sprite spriteWithFile:@"xxx.png"];
[game addChild: mySprite z:1];

childSprite = [Sprite spriteWithFile:@"yyy.png"];
[mySprite addChild:childSprite z:2];

Now if i run an action on mySprite, it gets ran on its children too.

Posted 2 years ago #
jd
Member

I had no idea you could attach sprites this way. Thanks Pablo!

Posted 2 years ago #
pabloruiz55
Member

also, if i have to remove it i do:

[game->mySprite removeAllChildrenWithCleanup:YES];
[game removeChild:mySprite cleanup:YES];

i don't know if it is necessary to remove its children before removing the sprite... Maybe someone else can tell us ;)

Posted 2 years ago #
Codemattic
Moderator

If you make your car a subclass of cocosNode then you can adopt the <CocosNodeOpacity> protocol and add the method:

-(void) setOpacity: (GLubyte) opacity;

which should iterate through its children, and set the opacity of each child. Now you should be able to animate the opacity of your car using FadeOut/In actions.

hth, Codemattic

Posted 2 years ago #

Codemattic
Moderator

-(void) setOpacity: (GLubyte) opacity
{
  for (CocosNode * child in children) {
    [child setOpacity: opacity];
  }
}
-(void) setRGB: (GLubyte)r :(GLubyte)g :(GLubyte)b;
{
  for (CocosNode * child in children) {
    [child setRGB: r : g : b];
  }
}

protocol

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