Shader.cpp

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

#include <GL/glew.h>
#include "Shader.hpp"

// Constructor generates the shader on the fly
Shader::Shader(const GLchar* vertexPath, const GLchar* fragmentPath) {
    // 1. Retrieve the vertex/fragment source code from filePath
    std::string vertexCode;
    std::string fragmentCode;
    std::ifstream vShaderFile;
    std::ifstream fShaderFile;
    // ensures ifstream objects can throw exceptions:
    vShaderFile.exceptions (std::ifstream::badbit);
    fShaderFile.exceptions (std::ifstream::badbit);
    try {
        // Open files
        vShaderFile.open(vertexPath);
        fShaderFile.open(fragmentPath);
        std::stringstream vShaderStream, fShaderStream;
        // Read file's buffer contents into streams
        vShaderStream << vShaderFile.rdbuf();
        fShaderStream << fShaderFile.rdbuf();
        // close file handlers
        vShaderFile.close();
        fShaderFile.close();
        // Convert stream into string
        vertexCode = vShaderStream.str();
        fragmentCode = fShaderStream.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. Compile shaders
    GLuint vertex, fragment;
    GLint success;
    GLchar infoLog[512];
    // Vertex Shader
    vertex = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertex, 1, &vShaderCode, NULL);
    glCompileShader(vertex);
    // Print compile errors if any
    glGetShaderiv(vertex, GL_COMPILE_STATUS, &success);
    if (!success)
    {
        glGetShaderInfoLog(vertex, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
    }
    // Fragment Shader
    fragment = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragment, 1, &fShaderCode, NULL);
    glCompileShader(fragment);
    // Print compile errors if any
    glGetShaderiv(fragment, GL_COMPILE_STATUS, &success);
    if (!success)
    {
        glGetShaderInfoLog(fragment, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << infoLog << std::endl;
    }
    // Shader Program
    this->Program = glCreateProgram();
    glAttachShader(this->Program, vertex);
    glAttachShader(this->Program, fragment);
    glLinkProgram(this->Program);
    // Print linking errors if any
    glGetProgramiv(this->Program, GL_LINK_STATUS, &success);
    if (!success)
    {
        glGetProgramInfoLog(this->Program, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infoLog << std::endl;
    }
    // Delete the shaders as they're linked into our program now and no longer necessery
    glDeleteShader(vertex);
    glDeleteShader(fragment);

}

// Uses the current shader
void Shader::use() const {
    glUseProgram(this->Program); 
}