图片变灰,采用shader就可以实现,

有2中方法,

1,像CCSprite一样create

2. 把CCSprite传进来,并把图片要不要变灰的flag传进来,具体实现看代码和后面的使用方法

-----------------------------------------

GraySprite.h

//
//  GraySprite.h
//  goddess
//
//  Created by rekoo on 13-7-23.
//
//
#ifndef __goddess__GraySprite__
#define __goddess__GraySprite__
#include "cocos2d.h"
#include "cocos-ext.h"
USING_NS_CC;
USING_NS_CC_EXT;
class GraySprite : public CCSprite
{
public:
    GraySprite();
    ~GraySprite();
                                           
    bool initWithTexture(CCTexture2D* texture,const CCRect&  rect);
    void draw();
    void initProgram();
    void listenBackToForeground(CCObject *obj);
                                           
    static GraySprite* create(const char *pszFileName);
                                           
};
#endif /* defined(__goddess__GraySprite__) */

GraySprite.cpp

//
//  GraySprite.cpp
//  goddess
//
//  Created by rekoo on 13-7-23.
//
//
// 用shader创建灰度图， 用法跟sprite一样
//  lua用法： local sprite = GraySprite:create("pic.png")
#include "GraySprite.h"
GraySprite::GraySprite()
{
}
GraySprite::~GraySprite()
{
}
GraySprite* GraySprite::create(const char *pszFileName)
{
    GraySprite* pRet = new GraySprite();
    if (pRet && pRet->initWithFile(pszFileName))
    {
        pRet->autorelease();
    }
    else
    {
        CC_SAFE_DELETE(pRet);
    }
                                       
    return pRet;
}
void GraySprite::listenBackToForeground(CCObject *obj)
{
    setShaderProgram(NULL);
    initProgram();
}
bool GraySprite::initWithTexture(CCTexture2D* texture,const CCRect& rect)
{
    if( CCSprite::initWithTexture(texture,rect) )
    {
                                                   
        CCSize s = getTexture()->getContentSizeInPixels();
                                        
        this->initProgram();
                                           
        return true;
    }
                                       
    return false;
}
void GraySprite::initProgram()
{
//    GLchar * fragSource = (GLchar*) CCString::createWithContentsOfFile(
//                                                                       CCFileUtils::sharedFileUtils()->fullPathForFilename("Shaders/example_Blur.fsh").c_str())->getCString();
                                       
  const  GLchar * pfrag =    "#ifdef GL_ES \n \
    precision mediump float; \n \
    #endif \n\
    uniform sampler2D u_texture; \n \
    varying vec2 v_texCoord; \n \
    varying vec4 v_fragmentColor; \n \
    void main(void) \n \
    { \n \
    float alpha = texture2D(u_texture,v_texCoord).a; \n \
    float grey = dot(texture2D(u_texture,v_texCoord).rgb,vec3(0.299,0.587,0.114)); \n \
    gl_FragColor = vec4(grey,grey,alpha); \n \
    } ";
                                       
                                    
    CCGLProgram* pProgram = new CCGLProgram();
    pProgram->initWithVertexShaderByteArray(ccPositionTextureColor_vert,pfrag);
    setShaderProgram(pProgram);
    pProgram->release();
                                       
    CHECK_GL_ERROR_DEBUG();
                                       
    getShaderProgram()->addAttribute(kCCAttributeNamePosition,kCCVertexAttrib_Position);
    getShaderProgram()->addAttribute(kCCAttributeNameColor,kCCVertexAttrib_Color);
    getShaderProgram()->addAttribute(kCCAttributeNameTexCoord,kCCVertexAttrib_TexCoords);
                                       
    CHECK_GL_ERROR_DEBUG();
                                       
    getShaderProgram()->link();
                                       
    CHECK_GL_ERROR_DEBUG();
                                       
    getShaderProgram()->updateUniforms();
                                       
}
void GraySprite::draw()
{
    ccGLEnableVertexAttribs(kCCVertexAttribFlag_PosColorTex );
    ccBlendFunc blend = getBlendFunc();
    ccGLBlendFunc(blend.src,blend.dst);
                                       
    getShaderProgram()->use();
    getShaderProgram()->setUniformsForBuiltins();
                                       
                                       
    ccGLBindTexture2D( getTexture()->getName());
                                       
    //
    // Attributes
    //
#define kQuadSize sizeof(m_sQuad.bl)
    long offset = (long)&m_sQuad;
                                       
    // vertex
    int diff = offsetof( ccV3F_C4B_T2F,vertices);
    glVertexAttribPointer(kCCVertexAttrib_Position,3,GL_FLOAT,GL_FALSE,kQuadSize,(void*) (offset + diff));
                                       
    // texCoods
    diff = offsetof( ccV3F_C4B_T2F,texCoords);
    glVertexAttribPointer(kCCVertexAttrib_TexCoords,2,(void*)(offset + diff));
                                       
    // color
    diff = offsetof( ccV3F_C4B_T2F,colors);
    glVertexAttribPointer(kCCVertexAttrib_Color,4,GL_UNSIGNED_BYTE,GL_TRUE,(void*)(offset + diff));
                                       
                                       
    glDrawArrays(GL_TRIANGLE_STRIP,4);
                                       
    CC_INCREMENT_GL_DRAWS(1);
}

--------------------------------

使用例子:

1. GraySprite * gs = GraySprite::create("01.png");

剩下跟CCSprite一样,设置位置,addChild等等

2. CCSprite * cs = CCSprite::create("02.png");

GraySprite::setGray(cs,1); //变灰

GraySprite::setGray(cs,0); //原色

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把GraySprte暴露出去,lua就可以调用,很方便