cocos2d-iphone – Cocos2d 2.0 – 忽略层/精灵透明区域的触摸

在CCLayer上实现扩展,并提供以下方法：

- (BOOL)isPixelTransparentAtLocation:(CGPoint)loc 
{   
    //Convert the location to the node space
    CGPoint location = [self convertToNodeSpace:loc];

    //This is the pixel we will read and test
    UInt8 pixel[4];

    //Prepare a render texture to draw the receiver on,so you are able to read the required pixel and test it    
    CGSize screenSize = [[CCDirector sharedDirector] winSize];
    CCRenderTexture* renderTexture = [[CCRenderTexture alloc] initWithWidth:screenSize.width
                                                                     height:screenSize.height
                                                                pixelFormat:kCCTexture2DPixelFormat_RGBA8888];

    [renderTexture begin];

    //Draw the layer
    [self draw];    

    //Read the pixel
    glReadPixels((GLint)location.x,(GLint)location.y,kHITTEST_WIDTH,kHITTEST_HEIGHT,GL_RGBA,GL_UNSIGNED_BYTE,pixel);

    //Cleanup
    [renderTexture end];
    [renderTexture release];

    //Test if the pixel's alpha byte is transparent
    return (pixel[3] == 0);
}