ShaderClass.h

#include <glad/glad.h>

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

class Shader
{
public:
    unsigned int ID;
    
	/* this function reads the given files in the project, throws exception when error occurs and compile the shaders and create a program with this.ID */
    Shader(const char* vertexPath, const char* fragmentPath)
    {
        /* ifstream used for reading */
        std::string vertexCode;
        std::string fragmentCode;
        std::ifstream vShaderFile;
        std::ifstream fShaderFile;
        /* exception part */
        vShaderFile.exceptions (std::ifstream::failbit | std::ifstream::badbit);
        fShaderFile.exceptions (std::ifstream::failbit | std::ifstream::badbit);
        try 
        {
            
            vShaderFile.open(vertexPath);
            fShaderFile.open(fragmentPath);
            std::stringstream vShaderStream, fShaderStream;
            
            vShaderStream << vShaderFile.rdbuf();
            fShaderStream << fShaderFile.rdbuf();		
            
            vShaderFile.close();
            fShaderFile.close();
            
            vertexCode = vShaderStream.str();
            fragmentCode = fShaderStream.str();			
        }
        catch (std::ifstream::failure e)
        {
            std::cout << "ERROR::SHADER::FILE_NOT_SUCCESFULLY_READ" << std::endl;
        }
        const char* vShaderCode = vertexCode.c_str();
        const char * fShaderCode = fragmentCode.c_str();
        
        unsigned int vertex, fragment;
        /* compiling the shaders and creating the program for this object */
        vertex = glCreateShader(GL_VERTEX_SHADER);
        glShaderSource(vertex, 1, &vShaderCode, NULL);
        glCompileShader(vertex);
        checkCompileErrors(vertex, "VERTEX");
        
        fragment = glCreateShader(GL_FRAGMENT_SHADER);
        glShaderSource(fragment, 1, &fShaderCode, NULL);
        glCompileShader(fragment);
        checkCompileErrors(fragment, "FRAGMENT");
        
        ID = glCreateProgram();
        glAttachShader(ID, vertex);
        glAttachShader(ID, fragment);
        glLinkProgram(ID);
        checkCompileErrors(ID, "PROGRAM");
        
        glDeleteShader(vertex);
        glDeleteShader(fragment);

    }

	/* shorten the name of use program */
    void use() const
    { 
        glUseProgram(ID); 
    }

	/* for the multiple use of the sending integer to the shaders */
    void setInt(const std::string &name, int value) const
    { 
        glUniform1i(glGetUniformLocation(ID, name.c_str()), value); 
    }
    

	/* for the multiple use of the sending float to the shaders */
    void setFloat(const std::string &name, float value) const
    { 
        glUniform1f(glGetUniformLocation(ID, name.c_str()), value); 
    }
    
	/* for the multiple use of the sending vector to the shaders */
	/* used for sending vector to the structs in the spotlight vertex shader */
    void setVec3(const std::string &name, float x, float y, float z) const
    { 
        glUniform3f(glGetUniformLocation(ID, name.c_str()), x, y, z); 
    }

	/* for the multiple use of the sending matrix to the shaders */
	/* used for sending view and projection matrices to the spotlight vertex shader */
	void setMat44(const std::string &name, float* mat) const
	{
		glUniformMatrix4fv(glGetUniformLocation(ID, name.c_str()), 1, GL_FALSE, mat);
	}

private:
    /* this is so unnecessary since the glad sends compiler error and there are no other explicit errors other than shader compilation error */
    void checkCompileErrors(GLuint shader, std::string type)
    {
        GLint success;
        GLchar infoLog[1024];
        if (type != "PROGRAM")
        {
            glGetShaderiv(shader, GL_COMPILE_STATUS, &success);
            if (!success)
            {
                glGetShaderInfoLog(shader, 1024, NULL, infoLog);
                std::cout << "ERROR::SHADER_COMPILATION_ERROR of type: " << type << "\n" << infoLog << "\n -- --------------------------------------------------- -- " << std::endl;
            }
        }
        else
        {
            glGetProgramiv(shader, GL_LINK_STATUS, &success);
            if (!success)
            {
                glGetProgramInfoLog(shader, 1024, NULL, infoLog);
                std::cout << "ERROR::PROGRAM_LINKING_ERROR of type: " << type << "\n" << infoLog << "\n -- --------------------------------------------------- -- " << std::endl;
            }
        }
    }
};