Cocos2dx - CCSprite使用 shader生成自己想要的颜色的图片

class BYGraySprite : public CCSprite{

public:
BYGraySprite();
virtual ~BYGraySprite();
static BYGraySprite* create(const char* pszFileName);
bool initWithTexture(CCTexture2D* pTexture, const CCRect& tRect);
virtual void draw();
};

#include "BYGraySprite.h"
BYGraySprite::BYGraySprite(){

}

BYGraySprite::~BYGraySprite(){

}

BYGraySprite* BYGraySprite::create( const char* pszFileName ){
BYGraySprite* graySprite = new BYGraySprite;
if (graySprite && graySprite->initWithFile(pszFileName)){
graySprite->autorelease();
return graySprite;
}else{
CC_SAFE_RELEASE(graySprite);
return NULL;
}
}

bool BYGraySprite::initWithTexture(CCTexture2D* pTexture, const CCRect& tRect ){
do{
CC_BREAK_IF(!CCSprite::initWithTexture(pTexture, tRect));

GLchar* pszFragSource =
"#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 \
// Convert to greyscale using NTSC weightings \n \
float grey = dot(texture2D(u_texture, v_texCoord).rgba, vec4(0.5, 0.0, 0.0,0.7)); \n \
gl_FragColor = vec4(grey, 0.0, 0.0, 0.0); \n \
}";

CCGLProgram* pProgram = new CCGLProgram();
pProgram->initWithVertexShaderByteArray(ccPositionTextureColor_vert, pszFragSource);
this->setShaderProgram(pProgram);
pProgram->release();
CHECK_GL_ERROR_DEBUG();

this->getShaderProgram()->addAttribute(kCCAttributeNamePosition, kCCVertexAttrib_Position);
this->getShaderProgram()->addAttribute(kCCAttributeNameColor, kCCVertexAttrib_Color);
this->getShaderProgram()->addAttribute(kCCAttributeNameTexCoord, kCCVertexAttrib_TexCoords);
CHECK_GL_ERROR_DEBUG();

this->getShaderProgram()->link();
CHECK_GL_ERROR_DEBUG();

this->getShaderProgram()->updateUniforms();
CHECK_GL_ERROR_DEBUG();

return true;
} while (0);
return false;
}

void BYGraySprite::draw(){
ccGLEnableVertexAttribs(kCCVertexAttribFlag_PosColorTex );
ccGLBlendFunc( m_sBlendFunc.src, m_sBlendFunc.dst );

this->getShaderProgram()->use();
this->getShaderProgram()->setUniformForModelViewProjectionMatrix();

ccGLBindTexture2D( this->getTexture()->getName() );

#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, GL_FLOAT, GL_FALSE, kQuadSize, (void*)(offset + diff));

// color
diff = offsetof( ccV3F_C4B_T2F, colors);
glVertexAttribPointer(kCCVertexAttrib_Color, 4, GL_UNSIGNED_BYTE, GL_TRUE, kQuadSize, (void*)(offset + diff));
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
CC_INCREMENT_GL_DRAWS(1);
}

BYGraySprite* graySprite = BYGraySprite::create("boss.png");
graySprite->setPosition(ccp(480,320) );
addChild(graySprite);