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,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();
}