Comment obtenir des informations alpha pixel Sprite dans cocos2d js/C++

Question

Je travaille sur un jeu de grattage et de gagner, j'ai utilisé le noeud clipper pour cela. Mais je veux savoir l'événement quand le sprite entier est clippe?

est-il une autre façon de le savoir, plz help me

Answer 1

I solved this issue by using following method:- 

I create one rendure texture and add an sprite on it. 

I found answer here:- http://discuss.cocos2d-x.org/t/render-texture-get-percentage-of-transparent/21123 
here is the code:- 

    var WINDOW_WIDTH = cc.director.getWinSize().width; 

    var WINDOW_HEIGHT = cc.director.getWinSize().height; 

    rt = new cc.RenderTexture(WINDOW_WIDTH, WINDOW_HEIGHT, 
    sprite.getTexture().getPixelFormat()); 
    rt.setPosition(WINDOW_WIDTH/2, WINDOW_HEIGHT/2); 
    this.addChild(rt, 5); 

getPercentageTransparent: function() { 
     // 
     var s = rt.getSprite().getContentSize(); 
     var tx = s.width; 
     var ty = s.height; 

     var bitsPerPixel = 4 * 8; 
     var bytesPerPixel = bitsPerPixel/8; 
     var bytesPerRow = bytesPerPixel * tx; 
     var myDataLength = bytesPerRow * ty; 

     var numberOfPixels = tx * ty; 
     var numberOfTransparent = 0; 

     var rawImagePixels = new Uint8Array(myDataLength); 
     rt.begin(); 
     gl.readPixels(0, 0, tx, ty, gl.RGBA, gl.UNSIGNED_BYTE, rawImagePixels); 
     rt.end(); 

     var x, y; 

     for (y = 0; y < ty; y++) { 
      // just want the last byte (alpha) for each pixel 
      for (x = 0; x < tx; x++) { 
       var alpha = rawImagePixels[(y * 4 * tx + ((x * 4) + 3))]; 

       if (alpha < 1) { 
        numberOfTransparent++; 
       } 
      } 
     } 
     cc.log("Number of pixels" + numberOfPixels); 
     cc.log("Number of Trasparent" + numberOfTransparent); 
     cc.log("percentage " + (numberOfTransparent/numberOfPixels) * 100); 
     return (numberOfTransparent/numberOfPixels) * 100; 
    },