#include "shader.h"

Shader::Shader(const GLchar* vertexPath, const GLchar* fragmentPath)
{
    //读取着色器的代码
    std::string vertexCode;
    std::string fragmentCode;
    std::ifstream vShaderFile;
    std::ifstream fShaderFile;

    //确保文件流会输出异常
    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
        vShaderStream << vShaderFile.rdbuf();
        fShaderStream << fShaderFile.rdbuf();

        vShaderFile.close();
        fShaderFile.close();

        vertexCode = vShaderStream.str();
        fragmentCode = fShaderStream.str();
    }
    catch(const std::ifstream::failure e)
    {
        std::cerr << "错误:读取文件失败,请检查文件是否存在!" << std::endl;
    }
    
    //2 编译着色器
    const char *vShaderCode = vertexCode.c_str();
    const char *fShaderCode = fragmentCode.c_str();

    unsigned int vertex, fragment;
    int success;
    char infoLog[512];

    //顶点着色器
    vertex = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertex, 1, &vShaderCode, NULL);
    glCompileShader(vertex);
    glGetShaderiv(vertex, GL_COMPILE_STATUS, &success);

    if (!success)
    {
        glGetShaderInfoLog(vertex, 512, NULL, infoLog);
        std::cout << "编译顶点着色器失败,错误信息:" << infoLog << std::endl;
    }
    //片元着色器
    fragment = glCreateShader(GL_FRAGMENT_SHADER);

    glShaderSource(fragment, 1, &fShaderCode, NULL);
    glCompileShader(fragment);
    glGetShaderiv(fragment, GL_COMPILE_STATUS, &success);

    if (!success)
    {
        glGetShaderInfoLog(fragment, 512, NULL, infoLog);
        std::cout << "编译片元着色器失败,错误信息:" << infoLog << std::endl;
    }
    // //着色器程序
    // ID = glad_glCreateProgram();
    // glAttachShader(ID, vertex);
    // glAttachShader(ID, fragment);
    // glLinkProgram(ID);
    // glGetProgramiv(ID, GL_LINK_STATUS, &success);
    // if (!success)
    // {
    //     glad_glGetProgramInfoLog(ID, 512, NULL, infoLog);
    //     std::cout << "编译片元着色器失败,错误信息:" << infoLog << std::endl;
    // }
    //链接着色器
    ID = glCreateProgram();
    glAttachShader(ID, vertex);
    glAttachShader(ID, fragment);
    glLinkProgram(ID);
    glGetProgramiv(ID, GL_LINK_STATUS, &success);
    if (!success)
    {
        glad_glGetProgramInfoLog(ID, 512, NULL, infoLog);
        std::cout << "链接着色器失败,错误信息:" << infoLog << std::endl;
    }
    //删除着色器
    glDeleteShader(vertex);
    glDeleteShader(fragment);
}
//使用着色器
void Shader::use()
{
    glUseProgram(ID);
}
//设置uniform变量
void Shader::setBool(const std::string& name, bool value) const
{
    glUniform1i(glGetUniformLocation(ID, name.c_str()), (int)value);
}
void Shader::setInt(const std::string& name, int value) const
{
    glUniform1i(glGetUniformLocation(ID, name.c_str()), value);
}
void Shader::setFloat(const std::string& name, float value) const
{
    glUniform1f(glGetUniformLocation(ID, name.c_str()), value);
}