cocos2dx 3.x版本 Sprite 灰度和彩色切换,无偏移

我从cocos2dx 3.x开始研究的，发现网上有很多在2.x变灰的例子，甚至需要改源码,而我个人偏向于静态方法的封装的用法，所以整合总结并测试了如下方法。在cocos2dx 3.4版本通过，关于偏移问题确实恶心，查阅很多博文已解决,有了这个方法我就准备在下一篇实现一个技能CD效果的通用方案。

static void SwitchGray (Sprite *sp, bool isGray)
{
GLchar* grayvsh =
"attribute vec4 a_position; \n \
attribute vec2 a_texCoord; \n \
attribute vec4 a_color; \n \
varying vec4 v_fragmentColor;\n \
varying vec2 v_texCoord;\n \
void main(void) \n \
{ \n \
gl_Position = CC_PMatrix * a_position;\n \
v_fragmentColor = a_color;\n \
v_texCoord = a_texCoord;\n \
}";
if(isGray)
{
GLchar* grayfsh=
"varying vec4 v_fragmentColor;\n \
varying vec2 v_texCoord;\n \
void main()\n \
{\n \
vec4 v_orColor = v_fragmentColor * texture2D(CC_Texture0, v_texCoord);\n \
float gray = dot(v_orColor.rgb, vec3(0.299, 0.587, 0.114));\n \
gl_FragColor = vec4(gray, gray, gray, v_orColor.a);\n \
}";
GLProgram* pProgram = new GLProgram();
pProgram->initWithVertexShaderByteArray(grayvsh, grayfsh);
sp->setShaderProgram(pProgram);
pProgram->release();
CHECK_GL_ERROR_DEBUG();
} else {
GLProgram* pProgram = new GLProgram();
//pProgram->initWithFilenames("gray.vsh", "color.fsh");
pProgram->initWithVertexShaderByteArray(grayvsh, ccPositionTextureColor_frag);
sp->setShaderProgram(pProgram);
pProgram->release();
CHECK_GL_ERROR_DEBUG();
}
sp->getShaderProgram()->addAttribute(GLProgram::ATTRIBUTE_NAME_POSITION,kCCVertexAttribFlag_Position);
sp->getShaderProgram()->addAttribute(GLProgram::ATTRIBUTE_NAME_POSITION, kCCVertexAttrib_Position);
sp->getShaderProgram()->addAttribute(GLProgram::ATTRIBUTE_NAME_COLOR, kCCVertexAttrib_Color);
sp->getShaderProgram()->addAttribute(GLProgram::ATTRIBUTE_NAME_TEX_COORD, kCCVertexAttrib_TexCoords);
CHECK_GL_ERROR_DEBUG();
sp->getShaderProgram()->link();
CHECK_GL_ERROR_DEBUG();
sp->getShaderProgram()->updateUniforms();
CHECK_GL_ERROR_DEBUG();
}