Cocos2d-x pixel-level touch Processing

Recently I have studied pixel-level touch processing. Sometimes we use an irregular image as a button. This irregular image is a PNG image of a rectangle, it is very likely that the actual effective display content of the image only accounts for a small part of the entire PNG image, and most of the remaining content is the transparent area of the PNG image. We want to filter out this transparent area, A button response is effective only when the actual content is touched.

At the beginning, I tried to get the pixel information of the texture directly through ccsprite, but the cocos2d-x didn't provide us with an interface to get the pixel information directly through ccsprite, and studied several online demos, it is found that this effect can be achieved by re-painting with rendertexture. The code is pasted below.

# Include "helloworldscene. H "# include" simpleaudioengine. H "using namespace cocos2d; using namespace cocosdenshion; ccscene * helloworld: Scene () {// 'Scene 'is an autorelease object ccscene * scene = ccscene: Create (); // 'player' is an autorelisted object helloworld * layer = helloworld: Create (); // Add layer as a child to scene-> addchild (layer ); // return the scene return scene;} bool helloworld: I Nit () {If (! Cclayer: Init () {return false;} This-> settouchenabled (true); this-> m_imgman = ccsprite: Create ("man.png "); this-> m_imgman-> setposition (CCP (400,200); this-> addchild (this-> m_imgman, 1); this-> m_prendertexture = ccrendertexture :: create (this-> m_imgman-> getcontentsize (). width, this-> m_imgman-> getcontentsize (). height, kcctexture2dpixelformat_rgba8888); this-> m_prendertexture-> ignoreanchorpointforposition (true); this-> m_prendertexture-> setposition (CCP (400,200 )); this-> m_prendertexture-> setanchorpoint (ccpointzero); this-> addchild (this-> m_prendertexture, 0, 1); Return true;} bool helloworld: cctouchbegan (cocos2d :: cctouch * ptouch, cocos2d: ccevent * pevent) {bool istouched = false; ccpoint touchpoint = ptouch-> getlocationinview (); ccpoint glpoint = ccdirector: shareddire () -> converttogl (touchpoint); If (this-> m_imgman-> boundingbox (). containspoint (glpoint) {cccolor4b color4b = {0, 0, 0}; ccpoint nodepos = This-> m_imgman-> converttouchtonodespace (ptouch); unsigned int x = nodepos. x; unsigned int y = This-> m_imgman-> getcontentsize (). height-nodepos. y; ccpoint point = This-> m_imgman-> getposition (); // start preparing to draw this-> m_prendertexture-> begin (); // The temporary sprite used for painting, the same image as the source image is ccsprite * ptempspr = ccsprite: createwithspriteframe (this-> m_imgman-> displayframe (); ptempspr-> setposition (CCP (ptempspr-> getcontentsize (). width/2, ptempspr-> getcontentsize (). height/2); // draw ptempspr-> visit (); // end draw this-> m_prendertexture-> end (); // obtain the information of each pixel on the canvas through the canvas and encapsulate it into ccimage * pimage = This-> m_prendertexture-> newccimage (); // obtain the pixel data unsigned char * Data _ = pimage-> getdata (); unsigned int * pixel = (unsigned int *) Data _; pixel = pixel + (y * (INT) ptempspr-> getcontentsize (). width) * 1 + x * 1; // R channel color4b. R = * pixel & 0xff; // G channel color4b. G = (* pixel> 8) & 0xff; // B uses color4b. B = (* pixel> 16) & 0xff; // alpha channel. What we use is Alpha color4b. A = (* pixel> 24) & 0xff; cclog ("alpha = % d of the currently clicked vertex", color4b. a); If (color4b. a> 50) {istouched = true;} else {istouched = false;} // clear the canvas content after painting. This-> m_prendertexture-> clear (0, 0, 0, 0, 0);} If (this-> m_plabtips) {This-> m_plabtips-> removefromparentandcleanup (true); this-> m_plabtips = NULL;} return istouched;} void helloworld :: cctouchended (cocos2d: cctouch * ptouch, cocos2d: ccevent * pevent) {If (this-> m_plabtips) {This-> m_plabtips-> removefromparentandcleanup (true ); this-> m_plabtips = NULL;} This-> m_plabtips = cclabelttf: Create ("click to a non-transparent pixel", "Courier", 30 ); this-> m_plabtips-> setanchorpoint (ccpointzero); this-> m_plabtips-> setposition (CCP (300366f, 100366f); this-> m_plabtips-> setcolor (ccyellow ); this-> addchild (this-> m_plabtips, 1);} void helloworld: Pull () {ccdirector: shareddire()-> gettouchdispatcher ()-> addtargeteddelegate (this, cclayer: gettouchpriority (), false );}

When a colored point is clicked, I asked the screen to display a yellow prompt and observe the printed log information:

When a transparent black area is clicked, no text is displayed on the screen. Observe the printed log information:

Implementation principle: I re-paint the image when I click it. During the re-painting process, I can get all the pixel information on the entire canvas through rendertexture, that is, the canvas, I have the same size as the canvas, so I can ensure that every pixel on the canvas is the pixel of the image I want to draw, then, the alpha channel value of the pixel is determined to determine whether the vertex is transparent. If the pixel is transparent, no touch response is made.

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Cocos2d-x pixel-level touch Processing