Shader.cpp

#include "Shader.h"
#include <iostream>
#include <fstream>
#include <sstream>

#include <GL/glew.h>    
#include <GLFW/glfw3.h> 

using namespace std;

Shader::Shader(const char* vertexPath, const char* fragmentPath){
    
    ifstream vertexFile;
    ifstream fragmentFile;
    stringstream vertexSStream;
    stringstream fragmentSStream;

    vertexFile.open(vertexPath);
    fragmentFile.open(fragmentPath);
    vertexFile.exceptions(ifstream::failbit | ifstream::badbit);
    fragmentFile.exceptions(ifstream::failbit | ifstream::badbit);

    try{
        if(!vertexFile.is_open() || !fragmentFile.is_open()){
            throw std::runtime_error("open file error");
        }
        vertexSStream << vertexFile.rdbuf();
        fragmentSStream << fragmentFile.rdbuf();
        
        vertexString = vertexSStream.str();
        fragmentString = fragmentSStream.str();

        vertexSource = vertexString.c_str();
        fragmentSource = fragmentString.c_str();

        unsigned int vertex, fragment;

        vertex = glCreateShader(GL_VERTEX_SHADER);
        glShaderSource(vertex, 1, &vertexSource, NULL);
        glCompileShader(vertex);
        checkCompileErrors(vertex, "VERTEX");

        fragment = glCreateShader(GL_FRAGMENT_SHADER);
        glShaderSource(fragment, 1, &fragmentSource, NULL);
        glCompileShader(fragment);
        checkCompileErrors(fragment, "FRAGMENT");

        ID = glCreateProgram();
        glAttachShader(ID, vertex);
        glAttachShader(ID, fragment);
        glLinkProgram(ID);
        checkCompileErrors(ID, "PROGRAM");
        glDeleteShader(vertex);
        glDeleteShader(fragment);
    }
    catch(const std::exception& ex){
        std::cerr << "Shader error: " << ex.what() << std::endl;
    }
}

void Shader::use() {
    glUseProgram(ID);
}

void Shader::checkCompileErrors(unsigned int ID, std::string type){
    int success;
    char infoLog[512];

    if(type!= "PROGRAM"){

        glGetShaderiv(ID, GL_COMPILE_STATUS, &success);

        if(!success){
            glGetShaderInfoLog(ID, 512, NULL, infoLog);
            cout << "shader compile error: " << infoLog << endl;
        }
    }
    else{
        
        glGetProgramiv(ID, GL_LINK_STATUS, &success);

        if(!success){
            glGetProgramInfoLog(ID, 512, NULL, infoLog);
            cout << "program linking error: " << infoLog << endl;
        }
    }
}