OpenGL第八章 材质material

当描述一个表面时，我们可以分别为三个光照分量定义一个材质颜色(Material Color)：
环境光照(Ambient Lighting)
漫反射光照(Diffuse Lighting)
镜面光照(Specular Lighting)
反光度(Shininess)
通过为每个分量指定一个颜色，我们就能够对表面的颜色输出有细粒度的控制了。现在，我们再添加一个反光度(Shininess)分量，结合上述的三个颜色，我们就有了全部所需的材质属性了：
ambient材质向量定义了在环境光照下这个表面反射的是什么颜色，通常与表面的颜色相同。
diffuse材质向量定义了在漫反射光照下表面的颜色漫反射颜色（和环境光照一样）也被设置为我们期望的物体颜色。
specular材质向量设置的是表面上镜面高光的颜色（或者甚至可能反映一个特定表面的颜色）。
shininess影响镜面高光的散射/半径。

//materialShader.fs
#version 330 core
out vec4 FragColor;

struct Material 
{
    
   vec3 ambient;
   vec3 diffuse;
   vec3 specular;
   float shininess;
};
uniform Material material;
//
struct Light {
    
    vec3 position;

    vec3 ambient;
    vec3 diffuse;
    vec3 specular;
};
uniform Light light;

in vec3 FragPos;
in vec3 Normal;
in vec3 LightPos;   //在视图坐标下的光源位置

uniform vec3 lightColor;//光源的颜色 在主程序中设置的
uniform vec3 objectColor;//物体的颜色 在主程序中设置的


void main()
{
    
      // ambient 环境光照
    float ambientStrength = 0.1;
    vec3 ambient  = light.ambient * material.ambient; //光照的影响因子乘以光源的颜色
    
     // diffuse 漫反射
    vec3 norm = normalize(Normal);//法线的单位向量
    vec3 lightDir = normalize(LightPos - FragPos);//在图形学中之前计算漫反射设置的光线方向是由物体指向光源的方向 只是为了方便计算没有物理意义
    float diff = max(dot(norm, lightDir), 0.0);//指向光源的方向再点成法线算出夹角 角度越小说明光源在头顶上（想象太阳在中午时候）光照最强
    vec3 diffuse  = light.diffuse * (diff * material.diffuse);
    
    // specular 镜面高光
    float specularStrength = 0.5;
    vec3 viewDir = normalize(-FragPos); // 由于在视图坐标下摄像机的位置为0 所以0-FragPos=-FragPos 方向由物体指向观察者（摄像机）
    vec3 reflectDir = reflect(-lightDir, norm);  //在图形学中之前计算漫反射设置的光线方向是由物体指向光源的方向 只是为了方便计算没有物理意义
    float spec = pow(max(dot(viewDir, reflectDir), 0.0), 32);//点成反射光和观察者的方向 32次幂表 shininess
    vec3 specular = light.specular * (spec * material.specular);
    
    vec3 result = (ambient + diffuse + specular) * objectColor;
    FragColor = vec4(result, 1.0);
}

//materialShader.vs 
//这里用的视图坐标系 所以相较于前一章并没有变化
#version 330 core
layout (location = 0) in vec3 aPos;//设置第一个属性为顶点位置
layout (location = 1) in vec3 aNormal;//设置第二个属性为法线

out vec3 FragPos;//输出一个物体的位置
out vec3 Normal;//输出经过法线矩阵变化后的法线向量
out vec3 LightPos;//输出一个在视图坐标下的光源的位置

uniform vec3 lightPos; //在modelShader.setVec3("lightPos", lightPos)中设置的光源位置

uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;


void main()
{
    
    gl_Position = projection * view * model * vec4(aPos, 1.0);
    FragPos = vec3(view * model * vec4(aPos, 1.0));//视图坐标下的物体的位置
    Normal = mat3(transpose(inverse(view * model))) * aNormal;//视图坐标下的 经过法线矩阵变化后的法线
    LightPos = vec3(view * vec4(lightPos, 1.0)); // 在视图坐标下的光源位置
}

//materialShader.cpp
#include "Shader.h"
#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"
#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>

void mouse_callback(GLFWwindow* window, double xpos, double ypos);
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
void processInput(GLFWwindow* window);

// settings
const unsigned int SCR_WIDTH = 800; //定义屏幕空间的大小
const unsigned int SCR_HEIGHT = 600;

// camera
glm::vec3 cameraPos = glm::vec3(0.0f, 0.0f, 3.0f);
glm::vec3 cameraFront = glm::vec3(0.0f, 0.0f, -1.0f);
glm::vec3 cameraUp = glm::vec3(0.0f, 1.0f, 0.0f);

bool firstMouse = true;
float yaw = -90.0f;	// 偏航初始化为-90.0度，因为偏航为0.0会导致指向右边的方向向量，所以我们最初向左旋转了一点。 
float pitch = 0.0f; //初始化俯仰角
float lastX = 800.0f / 2.0;//为了把初始位置设置为屏幕中心所以取屏幕空间大小的一半
float lastY = 600.0 / 2.0;
float fov = 45.0f;//初始的视场角

// timing
float deltaTime = 0.0f;	// time between current frame and last frame
float lastFrame = 0.0f;

//glm::vec3 lightPos(1.2f, 1.0f, 2.0f);

void processInput(GLFWwindow* window);
float vertices[] = {
    
    //顶点 //法线normal
    -0.5f, -0.5f, -0.5f,  0.0f,  0.0f, -1.0f,
     0.5f, -0.5f, -0.5f,  0.0f,  0.0f, -1.0f,
     0.5f,  0.5f, -0.5f,  0.0f,  0.0f, -1.0f,
     0.5f,  0.5f, -0.5f,  0.0f,  0.0f, -1.0f,
    -0.5f,  0.5f, -0.5f,  0.0f,  0.0f, -1.0f,
    -0.5f, -0.5f, -0.5f,  0.0f,  0.0f, -1.0f,

    -0.5f, -0.5f,  0.5f,  0.0f,  0.0f, 1.0f,
     0.5f, -0.5f,  0.5f,  0.0f,  0.0f, 1.0f,
     0.5f,  0.5f,  0.5f,  0.0f,  0.0f, 1.0f,
     0.5f,  0.5f,  0.5f,  0.0f,  0.0f, 1.0f,
    -0.5f,  0.5f,  0.5f,  0.0f,  0.0f, 1.0f,
    -0.5f, -0.5f,  0.5f,  0.0f,  0.0f, 1.0f,

    -0.5f,  0.5f,  0.5f, -1.0f,  0.0f,  0.0f,
    -0.5f,  0.5f, -0.5f, -1.0f,  0.0f,  0.0f,
    -0.5f, -0.5f, -0.5f, -1.0f,  0.0f,  0.0f,
    -0.5f, -0.5f, -0.5f, -1.0f,  0.0f,  0.0f,
    -0.5f, -0.5f,  0.5f, -1.0f,  0.0f,  0.0f,
    -0.5f,  0.5f,  0.5f, -1.0f,  0.0f,  0.0f,

     0.5f,  0.5f,  0.5f,  1.0f,  0.0f,  0.0f,
     0.5f,  0.5f, -0.5f,  1.0f,  0.0f,  0.0f,
     0.5f, -0.5f, -0.5f,  1.0f,  0.0f,  0.0f,
     0.5f, -0.5f, -0.5f,  1.0f,  0.0f,  0.0f,
     0.5f, -0.5f,  0.5f,  1.0f,  0.0f,  0.0f,
     0.5f,  0.5f,  0.5f,  1.0f,  0.0f,  0.0f,

    -0.5f, -0.5f, -0.5f,  0.0f, -1.0f,  0.0f,
     0.5f, -0.5f, -0.5f,  0.0f, -1.0f,  0.0f,
     0.5f, -0.5f,  0.5f,  0.0f, -1.0f,  0.0f,
     0.5f, -0.5f,  0.5f,  0.0f, -1.0f,  0.0f,
    -0.5f, -0.5f,  0.5f,  0.0f, -1.0f,  0.0f,
    -0.5f, -0.5f, -0.5f,  0.0f, -1.0f,  0.0f,

    -0.5f,  0.5f, -0.5f,  0.0f,  1.0f,  0.0f,
     0.5f,  0.5f, -0.5f,  0.0f,  1.0f,  0.0f,
     0.5f,  0.5f,  0.5f,  0.0f,  1.0f,  0.0f,
     0.5f,  0.5f,  0.5f,  0.0f,  1.0f,  0.0f,
    -0.5f,  0.5f,  0.5f,  0.0f,  1.0f,  0.0f,
    -0.5f,  0.5f, -0.5f,  0.0f,  1.0f,  0.0f
};
//定义一个vec3类型的数组来存位移矩阵
glm::vec3 cubePositions[] = {
    
glm::vec3(0.0f,  0.0f,  0.0f),
glm::vec3(2.0f,  5.0f, -15.0f),
glm::vec3(-1.5f, -2.2f, -2.5f),
glm::vec3(-3.8f, -2.0f, -12.3f),
glm::vec3(2.4f, -0.4f, -3.5f),
glm::vec3(-1.7f,  3.0f, -7.5f),
glm::vec3(1.3f, -2.0f, -2.5f),
glm::vec3(1.5f,  2.0f, -2.5f),
glm::vec3(1.5f,  0.2f, -1.5f),
glm::vec3(-1.3f,  1.0f, -1.5f)
};
int main()
{
    
    //Glfw:初始化和配置
    // ------------------------------
    glfwInit();
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

#ifdef __APPLE__
    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
#endif

    //glfw窗口创建
    // --------------------
    GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);//使用定义的屏幕空间的大小
    if (window == NULL)
    {
    
        std::cout << "Failed to create GLFW window" << std::endl;
        glfwTerminate();
        return -1;
    }
    glfwMakeContextCurrent(window);

    glfwSetCursorPosCallback(window, mouse_callback);
    glfwSetScrollCallback(window, scroll_callback);


    //首先我们要告诉GLFW，它应该隐藏光标，并捕捉(Capture)它。
    glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);

    //加载所有OpenGL函数指针
    // ---------------------------------------
    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
    {
    
        std::cout << "Failed to initialize GLAD" << std::endl;
        return -1;
    }

    // 配置全局opengl状态
    // -----------------------------
    glEnable(GL_DEPTH_TEST);

    // 构建并编译我们的shader程序
    // ------------------------------------
    Shader ourShader("shaderSampler.vs", "shaderSampler.fs");
    Shader modelShader("material.vs", "material.fs");
    Shader lightShader("lightShader.vs", "lightShader.fs");

    //建立和编译顶点数据(和缓冲区)，配置顶点属性 
    // ------------------------------------------------------------------

    unsigned int VBO, VAO,VAO2;
    glGenVertexArrays(1, &VAO);
    glGenBuffers(1, &VBO);
    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

 
    glBindVertexArray(VAO);
    //位置属性
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);
  
    //之后在顶点着色器layout (location = 1) in vec3 aNormal;//告诉GPU位置1的属性


    glGenVertexArrays(1, &VAO2);
    glBindVertexArray(VAO2);
    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    //位置属性
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);
    //法线属性
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float)));
    glEnableVertexAttribArray(1);

    // 加载并创建一个纹理
    // -------------------------
    unsigned int texture1, texture2;
    // texture 1
    // ---------
    glGenTextures(1, &texture1);
    glBindTexture(GL_TEXTURE_2D, texture1);
    // 设置纹理wrapping参数 
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    // 设置纹理filtering参数 
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    //加载图像，创建纹理和生成mipmaps //多级原理纹理
    int width, height, nrChannels;
    stbi_set_flip_vertically_on_load(true); // 告诉stb_image.h在y轴上翻转已加载的纹理。
                                            //为什么需要翻转Y轴是因为纹理图片开始位置是右上而我们顶点的坐标（0，0）点是左下
    unsigned char* data = stbi_load("container.jpg", &width, &height, &nrChannels, 0);
    if (data)
    {
    
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
        glGenerateMipmap(GL_TEXTURE_2D);
    }
    else
    {
    
        std::cout << "Failed to load texture" << std::endl;
    }
    stbi_image_free(data);
    // texture 2
    // ---------
    glGenTextures(1, &texture2);
    glBindTexture(GL_TEXTURE_2D, texture2);
    // 设置纹理wrapping参数
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    // 设置纹理filtering参数 
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    // load image, create texture and generate mipmaps
    //data = stbi_load(("aotu.jpg"), &width, &height, &nrChannels, 0);
    //data = stbi_load(("shanshui.jpg"), &width, &height, &nrChannels, 0);
    data = stbi_load(("awesomeface.png"), &width, &height, &nrChannels, 0);
    if (data)
    {
    
        //如果没有贴图请优先注意这个RGBA中的alpha(A)通道 如果你的贴图有alpha通道请务必使用RGBA模式否则无法显示贴图 
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
        glGenerateMipmap(GL_TEXTURE_2D);
    }
    else
    {
    
        std::cout << "Failed to load texture" << std::endl;
    }
    stbi_image_free(data);

    // 为每个采样器告诉opengl它属于哪个纹理单元(只需要做一次) 
    // -------------------------------------------------------------------------------------------
    ourShader.use();
    ourShader.setInt("texture1", 0);
    ourShader.setInt("texture2", 1);

   // ourShader.setVec3("lightPos", lightPos);
    //渲染循环
    // -----------
    while (!glfwWindowShouldClose(window))
    {
    
        float currentFrame = glfwGetTime();
        deltaTime = currentFrame - lastFrame;
        lastFrame = currentFrame;
        // -----
        processInput(window);

        // 渲染
        // ------
        glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // 清除上一帧的颜色缓冲 以及 深度测试缓冲

        // bind textures on corresponding texture units
        glActiveTexture(GL_TEXTURE0);
        glBindTexture(GL_TEXTURE_2D, texture1);
        glActiveTexture(GL_TEXTURE1);
        glBindTexture(GL_TEXTURE_2D, texture2);
        

        //激活着色器
        float angle = 20.0f * 0 * (float)glfwGetTime();//给一个glfwGetTime让模型旋转起来

       
        glm::mat4 projection = glm::mat4(1.0f);
        glm::mat4 view = glm::mat4(1.0f);
        glm::mat4 model = glm::mat4(1.0f);
        glm::vec3 lightPos = glm::vec3(cubePositions[2]);//光源位置
 
        ourShader.use();
        projection = glm::perspective(glm::radians(fov), 800.0f / 600.0f, 0.1f, 100.0f);//投影矩阵 参数：视口大小,屏幕宽高比，以及near和far
        view = glm::lookAt(cameraPos, cameraPos+cameraFront, cameraUp);//lookAt矩阵 参数：摄像机位置 ,观察目标的位置 ,竖直向上的方向
        model = glm::translate(model, cubePositions[0]);//把数组传进去给每一个新建的模型在世界坐标下有不同的位移
        model = glm::rotate(model, glm::radians(angle), glm::vec3(1.0f, 0.3f, 0.5f));
        

        lightShader.use();
        lightPos.x = 1.0f + sin(glfwGetTime()) * 2.0f;
        lightPos.y = sin(glfwGetTime() / 2.0f) * 1.0f;
        model = glm::mat4(1.0f);
        model = glm::translate(model, lightPos);//把数组传进去给每一个新建的模型在世界坐标下有不同的位移
        angle = 20.0f * 2 * (float)glfwGetTime();//给一个glfwGetTime让模型旋转起来
        model = glm::rotate(model, glm::radians(angle) * 0, glm::vec3(1.0f, 0.3f, 0.5f));
        lightShader.setMat4("model", model);
        lightShader.setMat4("projection", projection);
        lightShader.setMat4("view", view);
       
        glBindVertexArray(VAO);
        glDrawArrays(GL_TRIANGLES, 0, 36);

        modelShader.use();        
        model = glm::mat4(1.0f);        
        model = glm::translate(model, cubePositions[0]);//把数组传进去给每一个新建的模型在世界坐标下有不同的位移
        angle = 20.0f * 1 * (float)glfwGetTime();//给一个glfwGetTime让模型旋转起来
        model = glm::rotate(model, glm::radians(angle)*0, glm::vec3(1.0f, 0.5f, 0.5f));//rotate 模型位置 旋转角 旋转轴
        modelShader.setMat4("model", model);//设置模型变换矩阵
        modelShader.setMat4("projection", projection);//设置投影变化矩阵
        modelShader.setMat4("view", view);//设置视图变化矩阵
        modelShader.setVec3("objectColor",1,0.5,0.5);//设置物体的颜色
        modelShader.setVec3("lightColor", 1, 1, 1);//设置光源的颜色当然也可以设置一个uniform来设置变量进行设置
        modelShader.setVec3("lightPos", lightPos);//设置光源位置
        modelShader.setVec3("viewPos", cameraPos);//将相机的位置设置为观察位置

        modelShader.setVec3("material.ambient", 1.0f, 0.5f, 0.31f);
        modelShader.setVec3("material.diffuse", 1.0f, 0.5f, 0.31f);
        modelShader.setVec3("material.specular", 0.5f, 0.5f, 0.5f);
        modelShader.setFloat("material.shininess", 32.0f);
       
        modelShader.setVec3("light.ambient", 0.2f, 0.2f, 0.2f);
        modelShader.setVec3("light.diffuse", 0.5f, 0.5f, 0.5f); // 将光照调暗了一些以搭配场景
        modelShader.setVec3("light.specular", 1.0f, 1.0f, 1.0f);

        glm::vec3 lightColor;
        lightColor.x = sin(glfwGetTime() * 2.0f);
        lightColor.y = sin(glfwGetTime() * 0.7f);
        lightColor.z = sin(glfwGetTime() * 1.3f);

        glm::vec3 diffuseColor = lightColor * glm::vec3(0.5f); // 降低影响
        glm::vec3 ambientColor = diffuseColor * glm::vec3(0.2f); // 很低的影响

        modelShader.setVec3("light.ambient", ambientColor);
        modelShader.setVec3("light.diffuse", diffuseColor);
        glBindVertexArray(VAO2);
        glDrawArrays(GL_TRIANGLES, 0, 36);

  

        glfwSwapBuffers(window);
        glfwPollEvents();
    }

    glDeleteVertexArrays(1, &VAO);
    glDeleteBuffers(1, &VBO);

    glfwTerminate();
    return 0;
}


void processInput(GLFWwindow* window)
{
    
    if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
        glfwSetWindowShouldClose(window, true);


    float cameraSpeed = 5.5f * deltaTime;; // adjust accordingly
    if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS)
        cameraPos += cameraSpeed * cameraFront;
    if (glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS)
        cameraPos -= cameraSpeed * cameraFront;
    if (glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS)
        cameraPos -= glm::normalize(glm::cross(cameraFront, cameraUp)) * cameraSpeed;
    if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS)
        cameraPos += glm::normalize(glm::cross(cameraFront, cameraUp)) * cameraSpeed;
    if (glfwGetKey(window, GLFW_KEY_SPACE) == GLFW_PRESS)//这里给了一个空格键使我们可以在Y轴上移动
        cameraPos += cameraUp * cameraSpeed;

    //cameraPos.y = 0.0f;
    //可以通过把Y方向上的向量设置为0来使他成为一个FPS类型的摄像机只能在XZ平面上移动

}

void mouse_callback(GLFWwindow* window, double xposIn, double yposIn)
{
    
    float xpos = static_cast<float>(xposIn);
    float ypos = static_cast<float>(yposIn);

    // 这个bool变量初始时是设定为true的
    //我们在一开始的时候需要把他设为屏幕的中心点
    //如果不这样干 程序一开始就会调用回调函数指向你鼠标进去的时候所在屏幕的位置
    //这样就离中心点很远了
    if (firstMouse)
    {
    
        lastX = xpos;
        lastY = ypos;
        firstMouse = false;
    }

    //然后在鼠标的回调函数中我们计算当前帧和上一帧鼠标位置的偏移量：
    float xoffset = xpos - lastX;
    float yoffset = lastY - ypos; // y坐标是从下到上 
    lastX = xpos;
    lastY = ypos;

    float sensitivity = 0.1f; // sensitivity这个值可以随便设置
    xoffset *= sensitivity;
    yoffset *= sensitivity;

    yaw += xoffset;
    pitch += yoffset;

    // 为了保证摄像机不会整个翻车
    if (pitch > 89.0f)
        pitch = 89.0f;
    if (pitch < -89.0f)
        pitch = -89.0f;

    //在xz平面上看向Y轴
    //这里我们只更新了y值，仔细观察x和z分量也被影响了。从三角形中我们可以看到它们的值等于：
    //direction.x = cos(glm::radians(pitch));
    //direction.y = sin(glm::radians(pitch)); // 注意我们先把角度转为弧度
    //direction.z = cos(glm::radians(pitch));//这里Y轴更新确实会影响到Z轴但是不是很懂为什么直接等于cos(pitch)
    // 
    //
    //
    //这里我们只更新了y值，仔细观察x和z分量也被影响了。从三角形中我们可以看到它们的值等于：
    //direction.x = cos(glm::radians(yaw));
    //direction.y =1 // Y不变
    //direction.z = sin(glm::radians(yaw));
    // 
    //下面的等式相当于是先俯仰角的旋转变换完成之后再乘以这个偏航角
    //把上面两步合起来
    glm::vec3 front;
    front.x = cos(glm::radians(yaw)) * cos(glm::radians(pitch));
    front.y = sin(glm::radians(pitch));
    front.z = sin(glm::radians(yaw)) * cos(glm::radians(pitch));
    cameraFront = glm::normalize(front);
}

// glfw: whenever the mouse scroll wheel scrolls, this callback is called
// ----------------------------------------------------------------------
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
{
    
    //yoffset就是我们滚轮竖直滚动的方向
    if (fov >= 1.0f && fov <= 45.0f)
        fov -= yoffset;
    //为他设定一个边界 在1到45之间
    if (fov < 1.0f)
        fov = 1.0f;
    if (fov > 45.0f)
        fov = 45.0f;
}

//Shader.h
#include <glad/glad.h>
#include <string>
#include <fstream>
#include <sstream>
#include <iostream>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>

class Shader
{
    
public:
    unsigned int ID;
    // constructor generates the shader on the fly
    // ------------------------------------------------------------------------
    Shader(const char* vertexPath, const char* fragmentPath, const char* geometryPath = nullptr)
    {
    
        // 1. retrieve the vertex/fragment source code from filePath
        std::string vertexCode;
        std::string fragmentCode;
        std::string geometryCode;
        std::ifstream vShaderFile;
        std::ifstream fShaderFile;
        std::ifstream gShaderFile;
        // ensure ifstream objects can throw exceptions:
        vShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);
        fShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);
        gShaderFile.exceptions(std::ifstream::failbit | 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();
            // if geometry shader path is present, also load a geometry shader
            if (geometryPath != nullptr)
            {
    
                gShaderFile.open(geometryPath);
                std::stringstream gShaderStream;
                gShaderStream << gShaderFile.rdbuf();
                gShaderFile.close();
                geometryCode = gShaderStream.str();
            }
        }
        catch (std::ifstream::failure& e)
        {
    
            std::cout << "ERROR::SHADER::FILE_NOT_SUCCESFULLY_READ: " << e.what() << std::endl;
        }
        const char* vShaderCode = vertexCode.c_str();
        const char* fShaderCode = fragmentCode.c_str();
        // 2. compile shaders
        unsigned int vertex, fragment;
        // vertex shader
        vertex = glCreateShader(GL_VERTEX_SHADER);
        glShaderSource(vertex, 1, &vShaderCode, NULL);
        glCompileShader(vertex);
        checkCompileErrors(vertex, "VERTEX");
        // fragment Shader
        fragment = glCreateShader(GL_FRAGMENT_SHADER);
        glShaderSource(fragment, 1, &fShaderCode, NULL);
        glCompileShader(fragment);
        checkCompileErrors(fragment, "FRAGMENT");
        // if geometry shader is given, compile geometry shader
        unsigned int geometry;
        if (geometryPath != nullptr)
        {
    
            const char* gShaderCode = geometryCode.c_str();
            geometry = glCreateShader(GL_GEOMETRY_SHADER);
            glShaderSource(geometry, 1, &gShaderCode, NULL);
            glCompileShader(geometry);
            checkCompileErrors(geometry, "GEOMETRY");
        }
        // shader Program
        ID = glCreateProgram();
        glAttachShader(ID, vertex);
        glAttachShader(ID, fragment);
        if (geometryPath != nullptr)
            glAttachShader(ID, geometry);
        glLinkProgram(ID);
        checkCompileErrors(ID, "PROGRAM");
        // delete the shaders as they're linked into our program now and no longer necessery
        glDeleteShader(vertex);
        glDeleteShader(fragment);
        if (geometryPath != nullptr)
            glDeleteShader(geometry);

    }
    // activate the shader
    // ------------------------------------------------------------------------
    void use()
    {
    
        glUseProgram(ID);
    }
    // utility uniform functions
    // ------------------------------------------------------------------------
    void setBool(const std::string& name, bool value) const
    {
    
        glUniform1i(glGetUniformLocation(ID, name.c_str()), (int)value);
    }
    // ------------------------------------------------------------------------
    void setInt(const std::string& name, int value) const
    {
    
        glUniform1i(glGetUniformLocation(ID, name.c_str()), value);
    }
    // ------------------------------------------------------------------------
    void setFloat(const std::string& name, float value) const
    {
    
        glUniform1f(glGetUniformLocation(ID, name.c_str()), value);
    }
    // ------------------------------------------------------------------------
    void setVec2(const std::string& name, const glm::vec2& value) const
    {
    
        glUniform2fv(glGetUniformLocation(ID, name.c_str()), 1, &value[0]);
    }
    void setVec2(const std::string& name, float x, float y) const
    {
    
        glUniform2f(glGetUniformLocation(ID, name.c_str()), x, y);
    }
    // ------------------------------------------------------------------------
    void setVec3(const std::string& name, const glm::vec3& value) const
    {
    
        glUniform3fv(glGetUniformLocation(ID, name.c_str()), 1, &value[0]);
    }
    void setVec3(const std::string& name, float x, float y, float z) const
    {
    
        glUniform3f(glGetUniformLocation(ID, name.c_str()), x, y, z);
    }
    // ------------------------------------------------------------------------
    void setVec4(const std::string& name, const glm::vec4& value) const
    {
    
        glUniform4fv(glGetUniformLocation(ID, name.c_str()), 1, &value[0]);
    }
    void setVec4(const std::string& name, float x, float y, float z, float w)
    {
    
        glUniform4f(glGetUniformLocation(ID, name.c_str()), x, y, z, w);
    }
    // ------------------------------------------------------------------------
    void setMat2(const std::string& name, const glm::mat2& mat) const
    {
    
        glUniformMatrix2fv(glGetUniformLocation(ID, name.c_str()), 1, GL_FALSE, &mat[0][0]);
    }
    // ------------------------------------------------------------------------
    void setMat3(const std::string& name, const glm::mat3& mat) const
    {
    
        glUniformMatrix3fv(glGetUniformLocation(ID, name.c_str()), 1, GL_FALSE, &mat[0][0]);
    }
    // ------------------------------------------------------------------------
    void setMat4(const std::string& name, const glm::mat4& mat) const
    {
    
        glUniformMatrix4fv(glGetUniformLocation(ID, name.c_str()), 1, GL_FALSE, &mat[0][0]);
    }

private:
    // utility function for checking shader compilation/linking errors.
    // ------------------------------------------------------------------------
    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;
            }
        }
    }
};