#include <glad/glad.h>
#include <GLFW/glfw3.h>

#include "glm/glm.hpp"
#include "glm/gtc/matrix_transform.hpp"
#include "glm/gtc/type_ptr.hpp"

#include <iostream>
#include "stb_image.h"
#include "shader.h"
 
void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void processInput(GLFWwindow *window);
 
//
const unsigned int SCR_WIDTH = 1280;
const unsigned int SCR_HEIGHT = 720;
 
// float vertices[] = {
//     //               //
//     -0.5f, -0.5f, 0.0f, //1.0f, 0.0f, 0.0f,     //左
//     0.5f, -0.5f, 0.0f,  //0.0f, 1.0f, 0.0f,     //右
//     0.0f, 0.5f, 0.0f//, 0.0f, 0.0f, 1.0f        //上
// };
 
float rectVertices[] = {
  /* 位置         */  /* 颜色        */ /* 纹理坐标 */
  0.5f,  0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, //右上角
  0.5f, -0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, //右下角
 -0.5f, -0.5f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, //左下角
 -0.5f,  0.5f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f  //左上角
};
//
unsigned int indices[] = {
  0, 1, 3,        //
  1, 2, 3         //
};

int main()
{
    glm::vec4 vec(1.0f, 0.0f, 0.0f, 1.0f);
    glm::mat4 trans;
    //从这里就能看出单位矩阵的作用了.
    //初始化的trans是一个单位矩阵，让它平移到(1.0f, 1.0f, 0.0f)的位置产生了一个平移矩阵。
    trans = glm::translate(trans, glm::vec3(1.0f, 1.0f, 1.0f));
    
    vec = trans * vec;

    std::cout << "(" << vec.x << "," << vec.y << "," << vec.z << ")" << std::endl;

    return 0;
}

#if 0 
int main() {
    glfwInit();
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
 
    GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);
    if (window == NULL) {
        std::cout << "Failed to create GLFW window" << std::endl;
        glfwTerminate();
        return -1;
    }
    glfwMakeContextCurrent(window);
    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
 
    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {
        std::cout << "Failed to initialize GLAD" << std::endl;
        return -1;
    }
 
    //
    int nrAttributes;
    glGetIntegerv(GL_MAX_VERTEX_ATTRIBS, &nrAttributes);
    std::cout << "" << nrAttributes << std::endl;
 
    //着色器
    Shader shader("Shader.vs", "Shader.fs");
    
 


    // 
    unsigned int VBO, VAO;
    glGenVertexArrays(1, &VAO);
    glBindVertexArray(VAO);
 
    glGenBuffers(1, &VBO);
    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(rectVertices), rectVertices, GL_STATIC_DRAW);
 
    //位置属性
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);
    //颜色属性
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
    glEnableVertexAttribArray(1);
    //纹理属性
    glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
    glEnableVertexAttribArray(2);


    //
    //unsigned int VBO1, VAO1;
    //glGenVertexArrays(1, &VAO1);
    //glBindVertexArray(VAO1);
    //
    //glGenBuffers(1, &VBO1);
    //glBindBuffer(GL_ARRAY_BUFFER, VBO1);
    //glBufferData(GL_ARRAY_BUFFER, sizeof(vertices) / 2, vertices + 9, GL_STATIC_DRAW);
 
    //glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, (void*)0);
    //glEnableVertexAttribArray(0);
 
    unsigned int EBO;
    glGenBuffers(1, &EBO);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
 
    //纹理
    unsigned int texture;
    glGenTextures(1, &texture);
    glBindTexture(GL_TEXTURE_2D, texture);
    //设置纹理包装和过滤方式
    // glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    // glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    // glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
    // glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

    int width;
    int height;
    int nrChannels;
    stbi_set_flip_vertically_on_load(true);
    
    unsigned char *data = stbi_load("035.bmp", &width, &height, &nrChannels, 0);
    if (data)
    {
        GLint format = (nrChannels == 3) ? GL_RGB : GL_RGBA;
        glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, format, GL_UNSIGNED_BYTE, data);
        glGenerateMipmap(GL_TEXTURE_2D);

    } else {
        std::cout << "load image error" << std::endl;
    }

    stbi_image_free(data);

    while (!glfwWindowShouldClose(window)) {
        processInput(window);
 
        glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT);

        
        //float timeValue = glfwGetTime();
        //float greenValue = (sin(timeValue) / 2.0f) + 0.5f;
        //float greenValue = 1.0f;
        //int outColorLocation = glGetUniformLocation(shaderProgram, "ourColor");
        //glUniform4f(outColorLocation, 0.0f, greenValue, 0.0f, 1.0f);
        //glUseProgram(shaderProgram);
        shader.use();
        
        glBindTexture(GL_TEXTURE_2D, texture);
        /*
        * 
        * 
        */
        glBindVertexArray(VAO);
        // glDrawArrays(GL_TRIANGLES, 0, 3);
        //glUseProgram(shaderProgram1);
        //glBindVertexArray(VAO1);
        //glDrawArrays(GL_TRIANGLES, 0, 3);
        glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
 
        glfwSwapBuffers(window);
        glfwPollEvents();
    }
 
    glBindVertexArray(0);
    glDeleteVertexArrays(1, &VAO);
    glDeleteBuffers(1, &VBO);
    glfwTerminate();
    return 0;
}

void framebuffer_size_callback(GLFWwindow *window, int width, int height)
{
    glViewport(0, 0, width, height);
}
 
void processInput(GLFWwindow *window) {
    if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
        glfwSetWindowShouldClose(window, true);
}
#endif