Cocos2d 2.0 - 忽略对透明区域的图层/精灵的触摸 [英] Cocos2d 2.0 - Ignoring touches to transparent areas of layers/sprites

问题描述

我有一个应用程序，其中我有从PNG图像与透明度创建几个图层。这些层都在屏幕上彼此。我需要能够忽略给透明区域的图层的触摸，只是能够检测为触摸，当用户点击一个层的不透明区域...见图...

I have an app where I have several layers created from PNG images with transparency. These layers are all on the screen over each other. I need to be able to ignore touches given to transparent areas of layers and just be able to detect as touches, when the user taps on a non-transparent area of a layer... see pic...

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我该如何做？感谢。

推荐答案

这里有一个可能的解决方案。

Here you have a possible solution.

在CCLayer上实施扩展程序并提供此方法：

Implement an extension on CCLayer and provide this method:

- (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);
}

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