cocos2d for iPhone

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

1. 

   hugocosta
   Member

   Hi,

   I've searched and i can't find a way to fade in and out a CCLayer.
   I'm trying to fade in and then fade out a Menu.
   As i understand it a CCLayer is a CCNode so it would be possible to perform Actions on it, but the game crashes.

   I've tried doing it when i create it, and on the init method, same result.

   
-(void)showMenu {

   CCLayer* menuLayer = [MenuLayer node];
   id actionFadeIn = [CCFadeIn actionWithDuration:0.3];
   [menuLayer runAction:[CCSequence actions:actionFadeIn, nil]];

   [self addChild:menuLayer z:1];
}


   Thank you

   Posted 1 year ago #
2. 

   Tim
   Member

   Details on what the error message is would help. Looking at your code, is it an issue of running an action on something you haven't added yet? To do a fade in I believe you need to set the opacity to zero so that it can then fade in the node.

   I haven't tried doing this with a layer, but for sure the following works for a sprite (lifted from one of my earlier projects):

   Sprite *beeHive = [Sprite spriteWithFile:@"small-hive.png"];
   beeHive.opacity = 0;
   beeHive.position = cpv(350,150);
   [self addChild:beeHive z:5];
   id fadeHive = [FadeIn actionWithDuration:1];
   [beeHive runAction: fadeHive];

   Posted 1 year ago #
3. 

   hugocosta
   Member

   On the code i posted i'm running the action before adding the layer, it's true, it was code from the last trial. I've tried also doing it after.

   It does not produce any error on the console, the app just quits.

   setOpacity isn't a method on CCLayer, so i guess it can't be done.
   I will be doing it on the layer init method for all the menu sprites, i was just trying to be efficient.

   Thank you Tim.

   Posted 1 year ago #
4. 

   popgoblin
   Member

   Can anyone actually explain WHY CCLayer doesn't respond to setOpacity? Shouldn't it?

   Posted 1 year ago #
5. 

   CJ
   Moderator

   CCLayer doesn't do any drawing it's just a container. You'd have to implement the CCRGBAProtocol on the layer and then provide the methods to manually apply the color/opacity to its children.

   Take a look at CCCrossFadeTransition in CCTransition.m it has an example where it will render the layer to a texture first and then fade the texture.

   Posted 1 year ago #
6. 

   aerostat
   Member

   I found this somewhere I a while back and cannot remember where, I'm not taking credit, just passing it on ... (if I remember where I got it, I'll post a link here)

   Add this method to your CCLayer subclass, it is called by the engine when you give it a fade action. It passes the setOpacity call along to all children on the layer that support the proper protocol.

   // Set the opacity of all of our children that support it
   -(void) setOpacity: (GLubyte) opacity
   {
     for( CCNode *node in [self children] )
     {
       if( [node conformsToProtocol:@protocol( CCRGBAProtocol)] )
       {
         [(id<CCRGBAProtocol>) node setOpacity: opacity];
       }
     }
   }

   Posted 1 year ago #
7. 

   popgoblin
   Member

   Nice one. Thanks!

   Posted 1 year ago #
8. 

   Sam Brodkin
   Member

   Thanks aerostat. Here's a category to do what you suggested (then if you import the category, your layers will work with Fade actions):

   CCLayer+Opaque.h:

   #import "CCLayer.h"
   
   @interface CCLayer (CCLayer_Opaque)
   
   @end

   CCLayer+Opaque.m:

   #import "CCLayer+Opaque.h"
   
   @implementation CCLayer (CCLayer_Opaque)
   // Set the opacity of all of our children that support it
   -(void) setOpacity: (GLubyte) opacity
   {
       for( CCNode *node in [self children] )
       {
           if( [node conformsToProtocol:@protocol( CCRGBAProtocol)] )
           {
               [(id<CCRGBAProtocol>) node setOpacity: opacity];
           }
       }
   }
   -(GLubyte) opacity
   {
       for( CCNode *node in [self children] )
       {
           if( [node conformsToProtocol:@protocol( CCRGBAProtocol)] )
           {
               return [node opacity];
           }
       }
   }
   @end

   Posted 4 months ago #
9. 

   haqu
   Member

   to avoid compiler warning you should add (id<CCRGBAProtocol>) to getter too:

   - (GLubyte)opacity {
   	for (CCNode *node in [self children]) {
   		if ([node conformsToProtocol:@protocol(CCRGBAProtocol)]) {
   			return [(id<CCRGBAProtocol>)node opacity];
   		}
   	}
   	return 255;
   }

   Posted 3 months ago #

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