对cocos2d iphone的朝向处理的改进

我用cocos2d iphone作为我的iPhone/iPad游戏已经有一阵子了。cocos2d iphone是个经过考验的、方便使用的引擎，而且让你几乎可以很快地进行gameplay方面的开发。最近它加入了iPad的支持。然而，Apple对于iPad游戏的审批似乎比iPhone更严格了一些。因为iPad Human Interface Guideline中对于朝向敏感方面，对开发者做出了更高的要求。

鉴于以上原因，我准备让我的游戏变得对朝向改变更友好一点。在cocos2d iphone中，朝向的改变可以用注册UIDeviceOrientationDidChangeNotification事件后，再调用一些CCDirector的方法予以解决： 

 

代码

-  (BOOL)application:(UIApplication  * )application didFinishLaunchingWithOptions:(NSDictionary  * )launchOptions
{
         //  Enable orientation detection
    [[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications];
     //  Register orientation detection
    [[NSNotificationCenter defaultCenter]
     addObserver:self selector:@selector(orientationDidChanged:) name: @" UIDeviceOrientationDidChangeNotification "   object :nil];
         ......
}
- ( void ) orientationDidChanged:(NSNotification * )notification
{
    UIDeviceOrientation orientation  =  [[UIDevice currentDevice] orientation];
    [[CCDirector sharedDirector] setDeviceOrientation:(ccDeviceOrientation)orientation];
}

 然而，这个朝向的改变是很生硬的，没有任何切换动画。在做了一些功课之后，我决定自己写点代码搞定它。其实cocos2d中的朝向处理代码也没做什么事，无非就是调了一些必要的OS函数和坐标系转换。

所以我是这么做的：把CCDirector.applyLandscape里的所有gl调用都替换为CGAffineTransform的调用，而CGAffineTransform是可以根据时间插值的。最后把CGAffineTransform的矩阵转换为gl的矩阵：

代码

CGAffineTransform CGAffineTransformInterpolate( const  CGAffineTransform  * t0,  const  CGAffineTransform  * t1,  float  factor)
{
     //  clamp factor to [0, 1]
     if  ( factor  >   1  )
        factor  =   1 ;
     if  ( factor  <   0  )
        factor  =   0 ;

     return  CGAffineTransformMake(t0 -> a * ( 1 - factor)  +  t1 -> a * factor,
                                 t0 -> b * ( 1 - factor)  +  t1 -> b * factor,
                                 t0 -> c * ( 1 - factor)  +  t1 -> c * factor,
                                 t0 -> d * ( 1 - factor)  +  t1 -> d * factor,
                                 t0 -> tx * ( 1 - factor)  +  t1 -> tx * factor,
                                 t0 -> ty * ( 1 - factor)  +  t1 -> ty * factor);
}

//  in your CCDirector.m:

-  ( void ) setDeviceOrientation:(ccDeviceOrientation) orientation
{
     if ( deviceOrientation_  !=  orientation ) {
        deviceOrientation_  =  orientation;
        targetTransform_  =  CGAffineTransformIdentity;
        elapsedSinceLastOrientationChange_  =   0 ;

        CGSize s  =  [openGLView_ frame].size;
         float  w  =  s.width  /   2 ;
         float  h  =  s.height  /   2 ;

         switch ( deviceOrientation_) {
             case  CCDeviceOrientationPortrait:
                [[UIApplication sharedApplication] setStatusBarOrientation: UIInterfaceOrientationPortrait animated:NO];
                 break ;
             case  CCDeviceOrientationPortraitUpsideDown:
                [[UIApplication sharedApplication] setStatusBarOrientation: UIInterfaceOrientationPortraitUpsideDown animated:NO];

                targetTransform_  =  CGAffineTransformTranslate(targetTransform_, w, h);
                targetTransform_  =  CGAffineTransformRotate(targetTransform_, CC_DEGREES_TO_RADIANS( 180 ));
                targetTransform_  =  CGAffineTransformTranslate(targetTransform_,  - w,  - h);
                 break ;
             case  CCDeviceOrientationLandscapeLeft:
                [[UIApplication sharedApplication] setStatusBarOrientation: UIInterfaceOrientationLandscapeRight animated:NO];

                targetTransform_  =  CGAffineTransformTranslate(targetTransform_, w, h);
                targetTransform_  =  CGAffineTransformRotate(targetTransform_,  - CC_DEGREES_TO_RADIANS( 90 ));
                targetTransform_  =  CGAffineTransformTranslate(targetTransform_,  - h,  - w);
                 break ;
             case  CCDeviceOrientationLandscapeRight:
                [[UIApplication sharedApplication] setStatusBarOrientation: UIInterfaceOrientationLandscapeLeft animated:NO];

                targetTransform_  =  CGAffineTransformTranslate(targetTransform_, w, h);
                targetTransform_  =  CGAffineTransformRotate(targetTransform_, CC_DEGREES_TO_RADIANS( 90 ));
                targetTransform_  =  CGAffineTransformTranslate(targetTransform_,  - h,  - w);
                 break ;
             default :
                NSLog( @" Director: Unknown device orientation " );
                 break ;
        }
    }
}

- ( void ) applyLandscape
{
     static   float  m[ 16 ];

     if  ( elapsedSinceLastOrientationChange_  <   0.25f  )
    {
        currentTransform_  =  CGAffineTransformInterpolate( & currentTransform_,  & targetTransform_,
                                                         elapsedSinceLastOrientationChange_  /   0.25f );
        elapsedSinceLastOrientationChange_  +=  dt;
    }
     else
    {
        currentTransform_  =  targetTransform_;
    }

    CGAffineToGL( & currentTransform_, m);
    glMultMatrixf(m);
}

 

 现在，cocos2d的朝向处理就可以有漂亮的切换动画了。我把patch文件上传了，如果有兴趣的话可以下载看看。我是基于cocos2d iphone 0.99.0的代码做的。