vec2 someVec;
 
vec4 differentVec = someVec.xyxx;
 
vec3 anotherVec = differentVec.zyw;
 
vec4 otherVec = someVec.xxxx + anotherVec.yxzy;

class Shader
{
public:
	unsigned int ID;
 
	Shader(const GLchar* vertexPath,const GLchar* fragmentPath);
 
	void use();
	//uniform工具函数
	void setBool(const std::string &name, bool value) const;
	void setInt(const std::string& name, int value) const;
	void setFloat(const std::string& name, float value) const;
};

//1//从文件读取
	std::string vertexCode;
	std::string fragmentCode;
	std::ifstream vShaderFile;
	std::ifstream fShaderFile;
	//保证ifstream对象可以抛出异常
	vShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);
	fShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);
	try {
		//打开文件
		vShaderFile.open(vertexPath);
		fShaderFile.open(fragmentPath);
		std::stringstream vShaderStream, fShaderStream;
		//读取文件的缓冲内容到数据流中
		vShaderStream << vShaderFile.rdbuf();
		fShaderStream << fShaderFile.rdbuf();
		//关闭文件处理器
		vertexCode = vShaderStream.str();
		fragmentCode = fShaderStream.str();
	}
	catch (std::ifstream::failure e) {
		std::cout << "ERROR:SHADER::文件读取失败" << std::endl;
	}
	const char* vShaderCode = vertexCode.c_str();
	const char* fShaderCode = fragmentCode.c_str();

//抛出异常，表达式的值的类型可以是基本类型，亦可以是类
throw 表达式；
//try…catch
	try{
		语句组
	}
	catch(异常类型) {
		异常处理代码
	}
	...
	catch(异常类型) {
		异常处理代码
	}