shader.h

#ifndef  SHADER_H
#define SHADER_H

#include <string>
#include <fstream>
#include <sstream>
#include <iostream>

#include <GL\glew.h>
using namespace std;
class Shader
{
public:
	GLuint Program;
	Shader(const GLchar* vertexPath, const GLchar* fragmentPath);

	void Use() { glUseProgram(Program); }





};

Shader::Shader(const GLchar *vertexPath, const GLchar* fragmentPath)
{
	// 1. 从文件路径中获取顶点/片段着色器
	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::badbit); //失败时抛出成员类型异常
	fShaderFile.exceptions(std::ifstream::badbit);

	try
	{
		//打开文件
		vShaderFile.open(vertexPath);
		fShaderFile.open(fragmentPath);

		stringstream vShaderStream, fShaderStrem;
		vShaderStream << vShaderFile.rdbuf();//获得streambuff指针，重定向到string流
		fShaderStrem << fShaderFile.rdbuf();

		//关闭文件
		vShaderFile.close();
		fShaderFile.close();
        
		vertexCode = vShaderStream.str();
		fragmentCode = fShaderStrem.str();

	}
	catch(std::ifstream::failure e)
	{
		std::cout<< "ERROR::SHADER::FILE_NOT_SUCCESFULLY_READ" << std::endl;
	
	}
	const GLchar* vShaderCode = vertexCode.c_str();
	const GLchar* fShaderCode = fragmentCode.c_str();

	//2.编译连接着色器
	GLuint vertexShader, fragmentShader;
	GLint success;
	GLchar infoLog[512];
	vertexShader = glCreateShader(GL_VERTEX_SHADER);
	glShaderSource(vertexShader, 1, &vShaderCode, NULL);
	glCompileShader(vertexShader);
	glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
	if(!success)
	{
		glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
		std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
	
	}

	fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
	glShaderSource(fragmentShader, 1, &fShaderCode, NULL);
	glCompileShader(fragmentShader);
	glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);
	if (!success)
	{
		glGetShaderInfoLog(fragmentShader, 512, NULL, infoLog);
		std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << infoLog << std::endl;

	}

	Program = glCreateProgram();
	glAttachShader(Program, vertexShader);
	glAttachShader(Program, fragmentShader);
	glLinkProgram(Program);
	// 打印连接错误（如果有的话）
	glGetProgramiv(Program, GL_LINK_STATUS, &success);
	if (!success)
	{
		glGetProgramInfoLog(Program, 512, NULL, infoLog);
		std::cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infoLog << std::endl;
	}

	glDeleteShader(vertexShader);
	glDeleteShader(fragmentShader);
}

#endif // ! SHADER_H