跟着LearnOpenGL学习12--光照贴图

一、前言

在跟着LearnOpenGL学习11–材质中，我们讨论了让每个物体都拥有自己独特的材质从而对光照做出不同的反应的方法。这样子能够很容易在一个光照的场景中给每个物体一个独特的外观，但是这仍不能对一个物体的视觉输出提供足够多的灵活性。

我们将整个物体的材质定义为一个整体，但现实世界中的物体通常并不只包含有一种材质，而是由多种材质所组成。想想一辆汽车：它的外壳非常有光泽，车窗会部分反射周围的环境，轮胎不会那么有光泽，所以它没有镜面高光，轮毂非常闪亮（如果你洗车了的话）。汽车同样会有漫反射和环境光颜色，它们在整个物体上也不会是一样的，汽车有着许多种不同的环境光/漫反射颜色。总之，这样的物体在不同的部件上都有不同的材质属性。

所以，上一节中的那个材质系统是肯定不够的，它只是一个最简单的模型，所以我们需要拓展之前的系统，引入漫反射贴图和镜面光贴图(Map)。这允许我们对物体的漫反射分量（以及间接地对环境光分量，它们几乎总是一样的）和镜面光分量有着更精确的控制。

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二、漫反射贴图

我们希望通过某种方式对物体的每个片段单独设置漫反射颜色。有能够让我们根据片段在物体上的位置来获取颜色值的系统吗？

这可能听起来很熟悉，而且事实上这个系统我们已经使用很长时间了。这听起来很像在之前教程中详细讨论过的纹理，而这基本就是这样：一个纹理。

我们仅仅是对同样的原理使用了不同的名字：其实都是使用一张覆盖物体的图像，让我们能够逐片段索引其独立的颜色值。

在光照场景中，它通常叫做一个漫反射贴图(Diffuse Map)（3D艺术家通常都这么叫它），它是一个表现了物体所有的漫反射颜色的纹理图像。

为了演示漫反射贴图，我们将会使用下面的图片，它是一个有钢边框的木箱：

在着色器中使用漫反射贴图的方法和纹理教程中是完全一样的。但这次我们会将纹理储存为Material结构体中的一个sampler2D。我们将之前定义的vec3漫反射颜色向量 替换为 漫反射贴图。

注意：sampler2D是所谓的不透明类型(Opaque Type)，也就是说我们不能将它实例化，只能通过uniform来定义它。如果我们使用除uniform以外的方法（比如函数的参数）实例化这个结构体，GLSL会抛出一些奇怪的错误。这同样也适用于任何封装了不透明类型的结构体。

我们也移除了环境光材质颜色向量，因为环境光颜色在几乎所有情况下都等于漫反射颜色，所以我们不需要将它们分开储存：

struct Material { //材质描述结构体sampler2D diffuse;  //漫反射贴图vec3 specular;      //镜面反射光照float shininess;    //反光度
};
uniform Material material;  //材质

添加纹理

1、添加纹理坐标

//顶点数据
//---------------------------------------------------------------------
float vertices[] = {//顶点坐标             //法线坐标            //纹理坐标-0.5f, -0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  0.0f,  0.0f,0.5f, -0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  1.0f,  0.0f,0.5f,  0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  1.0f,  1.0f,0.5f,  0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  1.0f,  1.0f,-0.5f,  0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  0.0f,  1.0f,-0.5f, -0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  0.0f,  0.0f,-0.5f, -0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  0.0f,  0.0f,0.5f, -0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  1.0f,  0.0f,0.5f,  0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  1.0f,  1.0f,0.5f,  0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  1.0f,  1.0f,-0.5f,  0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  0.0f,  1.0f,-0.5f, -0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  0.0f,  0.0f,-0.5f,  0.5f,  0.5f, -1.0f,  0.0f,  0.0f,  1.0f,  0.0f,-0.5f,  0.5f, -0.5f, -1.0f,  0.0f,  0.0f,  1.0f,  1.0f,-0.5f, -0.5f, -0.5f, -1.0f,  0.0f,  0.0f,  0.0f,  1.0f,-0.5f, -0.5f, -0.5f, -1.0f,  0.0f,  0.0f,  0.0f,  1.0f,-0.5f, -0.5f,  0.5f, -1.0f,  0.0f,  0.0f,  0.0f,  0.0f,-0.5f,  0.5f,  0.5f, -1.0f,  0.0f,  0.0f,  1.0f,  0.0f,0.5f,  0.5f,  0.5f,  1.0f,  0.0f,  0.0f,  1.0f,  0.0f,0.5f,  0.5f, -0.5f,  1.0f,  0.0f,  0.0f,  1.0f,  1.0f,0.5f, -0.5f, -0.5f,  1.0f,  0.0f,  0.0f,  0.0f,  1.0f,0.5f, -0.5f, -0.5f,  1.0f,  0.0f,  0.0f,  0.0f,  1.0f,0.5f, -0.5f,  0.5f,  1.0f,  0.0f,  0.0f,  0.0f,  0.0f,0.5f,  0.5f,  0.5f,  1.0f,  0.0f,  0.0f,  1.0f,  0.0f,-0.5f, -0.5f, -0.5f,  0.0f, -1.0f,  0.0f,  0.0f,  1.0f,0.5f, -0.5f, -0.5f,  0.0f, -1.0f,  0.0f,  1.0f,  1.0f,0.5f, -0.5f,  0.5f,  0.0f, -1.0f,  0.0f,  1.0f,  0.0f,0.5f, -0.5f,  0.5f,  0.0f, -1.0f,  0.0f,  1.0f,  0.0f,-0.5f, -0.5f,  0.5f,  0.0f, -1.0f,  0.0f,  0.0f,  0.0f,-0.5f, -0.5f, -0.5f,  0.0f, -1.0f,  0.0f,  0.0f,  1.0f,-0.5f,  0.5f, -0.5f,  0.0f,  1.0f,  0.0f,  0.0f,  1.0f,0.5f,  0.5f, -0.5f,  0.0f,  1.0f,  0.0f,  1.0f,  1.0f,0.5f,  0.5f,  0.5f,  0.0f,  1.0f,  0.0f,  1.0f,  0.0f,0.5f,  0.5f,  0.5f,  0.0f,  1.0f,  0.0f,  1.0f,  0.0f,-0.5f,  0.5f,  0.5f,  0.0f,  1.0f,  0.0f,  0.0f,  0.0f,-0.5f,  0.5f, -0.5f,  0.0f,  1.0f,  0.0f,  0.0f,  1.0f
};

2、修改顶点着色器，读取纹理坐标并输出

#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec3 aNormal;
layout (location = 2) in vec2 aTexCoord;......void main()
{......TexCoord = aTexCoord;gl_Position = projection * view * vec4(aPos, 1.0f);
}

3、修改片段着色器，使用纹理坐标

#version 330 corein vec3 FragPos;
in vec3 Normal;
in vec2 TexCoord;out vec4 FragColor;uniform vec3 viewPos;   //观察者坐标struct Material { //材质描述结构体sampler2D diffuse;  //漫反射贴图vec3 specular;      //镜面反射光照float shininess;    //反光度
};
uniform Material material;  //材质struct Light {  //光照强度vec3 position;vec3 ambient;vec3 diffuse;vec3 specular;
};
uniform Light light;void main()
{//环境光照vec3 ambient = light.ambient * texture(material.diffuse, TexCoord).rgb;//漫反射光照vec3 norm = normalize(Normal);vec3 lightDir = normalize(light.position - FragPos);float diff = max(dot(norm, lightDir), 0.0);vec3 diffuse = light.diffuse * diff * texture(material.diffuse, TexCoord).rgb;//镜面反射光照vec3 viewDir = normalize(viewPos - FragPos);vec3 reflectDir = reflect(-lightDir, norm);float spec = pow(max(dot(viewDir, reflectDir), 0.0), material.shininess);vec3 specular = light.specular * (spec * material.specular);vec3 result = ambient + diffuse + specular;FragColor = vec4(result, 1.0);
}

4、修改属性指针，适配纹理坐标

//设定顶点属性指针
//位置属性
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
//法向量属性
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);//光源(VBO用上面的)
//----------------------------------------------------------------
unsigned int lightVAO;
glGenVertexArrays(1, &lightVAO);     //创建顶点数组对象
glBindVertexArray(lightVAO);         //绑定VAOglBindBuffer(GL_ARRAY_BUFFER, VBO);     //将VBO与GL_ARRAY_BUFFER缓冲区绑定glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);

5、导入纹理

//从文件导入一个2D纹理
// ----------------------------------------------------------------------
unsigned int loadTexture(char const * path)
{unsigned int textureID;glGenTextures(1, &textureID);int width, height, nrComponents;unsigned char *data = stbi_load(path, &width, &height, &nrComponents, 0);if (data) {GLenum format;if (nrComponents == 1)format = GL_RED;else if (nrComponents == 3)format = GL_RGB;else if (nrComponents == 4)format = GL_RGBA;glBindTexture(GL_TEXTURE_2D, textureID);glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, format, GL_UNSIGNED_BYTE, data);glGenerateMipmap(GL_TEXTURE_2D);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);stbi_image_free(data);} else {std::cout << "Texture failed to load at path: " << path << std::endl;stbi_image_free(data);}return textureID;
}//创建纹理
//----------------------------------------------------------------
unsigned int diffuseMap = loadTexture("C:/Qt_Pro/OpenGL_GLFW/Sources/container2.png");

6、赋值纹理

//赋值纹理
objectShader.use();
objectShader.setInt("material.diffuse", 0);

7、绑定纹理

while (!glfwWindowShouldClose(window))  //如果用户准备关闭参数window所指定的窗口，那么此接口将会返回GL_TRUE，否则将会返回GL_FALSE
{......//绑定纹理glActiveTexture(GL_TEXTURE0);glBindTexture(GL_TEXTURE_2D, diffuseMap);//绘制三角形glBindVertexArray(objectVAO);             //绑定VAOglDrawArrays(GL_TRIANGLES, 0, 36);......
}

使用了漫反射贴图之后，细节再一次得到惊人的提升，这次箱子有了光照开始闪闪发光（字面意思也是）了。你的箱子看起来可能像这样：

完整代码

被投光物体顶点着色器

#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec3 aNormal;
layout (location = 2) in vec2 aTexCoord;uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;out vec3 FragPos;
out vec3 Normal;
out vec2 TexCoord;void main()
{FragPos = vec3(model * vec4(aPos, 1.0));Normal = mat3(transpose(inverse(model))) * aNormal;TexCoord = aTexCoord;gl_Position = projection * view * vec4(aPos, 1.0f);
}

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被投光物体片段着色器

#version 330 corein vec3 FragPos;
in vec3 Normal;
in vec2 TexCoord;out vec4 FragColor;uniform vec3 viewPos;   //观察者坐标struct Material { //材质描述结构体sampler2D diffuse;  //漫反射贴图vec3 specular;      //镜面反射光照float shininess;    //反光度
};
uniform Material material;  //材质struct Light {  //光照强度vec3 position;vec3 ambient;vec3 diffuse;vec3 specular;
};
uniform Light light;void main()
{//环境光照vec3 ambient = light.ambient * texture(material.diffuse, TexCoord).rgb;//漫反射光照vec3 norm = normalize(Normal);vec3 lightDir = normalize(light.position - FragPos);float diff = max(dot(norm, lightDir), 0.0);vec3 diffuse = light.diffuse * diff * texture(material.diffuse, TexCoord).rgb;//镜面反射光照vec3 viewDir = normalize(viewPos - FragPos);vec3 reflectDir = reflect(-lightDir, norm);float spec = pow(max(dot(viewDir, reflectDir), 0.0), material.shininess);vec3 specular = light.specular * (spec * material.specular);vec3 result = ambient + diffuse + specular;FragColor = vec4(result, 1.0);
}

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main.cpp

#include "mainwindow.h"
#include <QApplication>//在包含GLFW的头文件之前包含了GLAD的头文件;
//GLAD的头文件包含了正确的OpenGL头文件（例如GL/gl.h）;
//所以需要在其它依赖于OpenGL的头文件之前包含GLAD;
#include <glad/glad.h>
#include <GLFW/glfw3.h>//GLM
//#include <glm/glm.hpp>
//#include <glm/gtc/matrix_transform.hpp>
//#include <glm/gtc/type_ptr.hpp>#include <iostream>
#include <QDebug>#include "shader.h"
#include "stb_image.h"
#include "camera.h"void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void mouse_callback(GLFWwindow* window, double xposIn, double yposIn);
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
void processInput(GLFWwindow *window);
unsigned int loadTexture(char const * path);// settings
const unsigned int SCR_WIDTH = 1920;
const unsigned int SCR_HEIGHT = 1080;//Camera
Camera camera(glm::vec3(0.0f, 0.0f, 3.0f));
float lastX =  SCR_WIDTH / 2.0;
float lastY =  SCR_HEIGHT / 2.0;
bool firstMouse = true;float deltaTime = 0.0f; // 当前帧与上一帧的时间差
float lastFrame = 0.0f; // 上一帧的时间//Light
glm::vec3 lightPos(1.2f, 1.0f, 2.0f);using namespace std;int main(int argc, char *argv[])
{QApplication a(argc, argv);//MainWindow w;//w.show();//初始化GLFW//--------------------glfwInit();//配置GLFW//--------------------//告诉GLFW使用的OpenGL本是3.3glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);//告诉GLFW使用的是核心模式（Core-profile）glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);//创建一个新的OpenGL环境和窗口//-----------------------------------GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);if (window == NULL){std::cout << "Failed to create GLFW window" << std::endl;glfwTerminate();    //glfw销毁窗口和OpenGL环境，并释放资源return -1;}//设置参数window中的窗口所关联的OpenGL环境为当前环境//-----------------------------------glfwMakeContextCurrent(window);//设置窗口尺寸改变大小时的回调函数（窗口尺寸发送改变时会自动调用）//-----------------------------------glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);//设置鼠标事件的回调函数（鼠标移动时会自动调用）//-----------------------------------glfwSetCursorPosCallback(window, mouse_callback);//设置鼠标滚轮事件的回调函数（鼠标滚轮移动时会自动调用）//-----------------------------------glfwSetScrollCallback(window, scroll_callback);//告诉GLFW捕捉鼠标glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);//glad加载系统相关的OpenGL函数指针//---------------------------------------if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)){std::cout << "Failed to initialize GLAD" << std::endl;return -1;}//开启深度测试glEnable(GL_DEPTH_TEST);Shader objectShader("C:/Qt_Pro/OpenGL_GLFW/shader/shader.vs","C:/Qt_Pro/OpenGL_GLFW/shader/shader.fs");Shader lightShader("C:/Qt_Pro/OpenGL_GLFW/shader/light_cube.vs","C:/Qt_Pro/OpenGL_GLFW/shader/light_cube.fs");//顶点数据//---------------------------------------------------------------------float vertices[] = {//顶点坐标             //法线坐标            //纹理坐标-0.5f, -0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  0.0f,  0.0f,0.5f, -0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  1.0f,  0.0f,0.5f,  0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  1.0f,  1.0f,0.5f,  0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  1.0f,  1.0f,-0.5f,  0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  0.0f,  1.0f,-0.5f, -0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  0.0f,  0.0f,-0.5f, -0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  0.0f,  0.0f,0.5f, -0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  1.0f,  0.0f,0.5f,  0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  1.0f,  1.0f,0.5f,  0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  1.0f,  1.0f,-0.5f,  0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  0.0f,  1.0f,-0.5f, -0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  0.0f,  0.0f,-0.5f,  0.5f,  0.5f, -1.0f,  0.0f,  0.0f,  1.0f,  0.0f,-0.5f,  0.5f, -0.5f, -1.0f,  0.0f,  0.0f,  1.0f,  1.0f,-0.5f, -0.5f, -0.5f, -1.0f,  0.0f,  0.0f,  0.0f,  1.0f,-0.5f, -0.5f, -0.5f, -1.0f,  0.0f,  0.0f,  0.0f,  1.0f,-0.5f, -0.5f,  0.5f, -1.0f,  0.0f,  0.0f,  0.0f,  0.0f,-0.5f,  0.5f,  0.5f, -1.0f,  0.0f,  0.0f,  1.0f,  0.0f,0.5f,  0.5f,  0.5f,  1.0f,  0.0f,  0.0f,  1.0f,  0.0f,0.5f,  0.5f, -0.5f,  1.0f,  0.0f,  0.0f,  1.0f,  1.0f,0.5f, -0.5f, -0.5f,  1.0f,  0.0f,  0.0f,  0.0f,  1.0f,0.5f, -0.5f, -0.5f,  1.0f,  0.0f,  0.0f,  0.0f,  1.0f,0.5f, -0.5f,  0.5f,  1.0f,  0.0f,  0.0f,  0.0f,  0.0f,0.5f,  0.5f,  0.5f,  1.0f,  0.0f,  0.0f,  1.0f,  0.0f,-0.5f, -0.5f, -0.5f,  0.0f, -1.0f,  0.0f,  0.0f,  1.0f,0.5f, -0.5f, -0.5f,  0.0f, -1.0f,  0.0f,  1.0f,  1.0f,0.5f, -0.5f,  0.5f,  0.0f, -1.0f,  0.0f,  1.0f,  0.0f,0.5f, -0.5f,  0.5f,  0.0f, -1.0f,  0.0f,  1.0f,  0.0f,-0.5f, -0.5f,  0.5f,  0.0f, -1.0f,  0.0f,  0.0f,  0.0f,-0.5f, -0.5f, -0.5f,  0.0f, -1.0f,  0.0f,  0.0f,  1.0f,-0.5f,  0.5f, -0.5f,  0.0f,  1.0f,  0.0f,  0.0f,  1.0f,0.5f,  0.5f, -0.5f,  0.0f,  1.0f,  0.0f,  1.0f,  1.0f,0.5f,  0.5f,  0.5f,  0.0f,  1.0f,  0.0f,  1.0f,  0.0f,0.5f,  0.5f,  0.5f,  0.0f,  1.0f,  0.0f,  1.0f,  0.0f,-0.5f,  0.5f,  0.5f,  0.0f,  1.0f,  0.0f,  0.0f,  0.0f,-0.5f,  0.5f, -0.5f,  0.0f,  1.0f,  0.0f,  0.0f,  1.0f};//物体//----------------------------------------------------------------unsigned int VBO, objectVAO;glGenVertexArrays(1, &objectVAO);     //创建顶点数组对象glGenBuffers(1, &VBO);          //创建顶点缓冲对象glBindBuffer(GL_ARRAY_BUFFER, VBO);     //将VBO与GL_ARRAY_BUFFER缓冲区绑定glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);  //将顶点数据复制到GL_ARRAY_BUFFER缓冲区，之后可通过VBO进行操作glBindVertexArray(objectVAO);         //绑定VAO//设定顶点属性指针//位置属性glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);glEnableVertexAttribArray(0);//法向量属性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);//光源(VBO用上面的)//----------------------------------------------------------------unsigned int lightVAO;glGenVertexArrays(1, &lightVAO);     //创建顶点数组对象glBindVertexArray(lightVAO);         //绑定VAOglBindBuffer(GL_ARRAY_BUFFER, VBO);     //将VBO与GL_ARRAY_BUFFER缓冲区绑定glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);glEnableVertexAttribArray(0);//创建纹理//----------------------------------------------------------------unsigned int diffuseMap = loadTexture("C:/Qt_Pro/OpenGL_GLFW/Sources/container2.png");//赋值纹理objectShader.use();objectShader.setInt("material.diffuse", 0);//渲染循环//我们可不希望只绘制一个图像之后我们的应用程序就立即退出并关闭窗口;//我们希望程序在我们主动关闭它之前不断绘制图像并能够接受用户输入;//因此，我们需要在程序中添加一个while循环，它能在我们让GLFW退出前一直保持运行;//------------------------------------------------------------------------------while (!glfwWindowShouldClose(window))  //如果用户准备关闭参数window所指定的窗口，那么此接口将会返回GL_TRUE，否则将会返回GL_FALSE{//更新时间差float currentFrame = static_cast<float>(glfwGetTime());deltaTime = currentFrame - lastFrame;lastFrame = currentFrame;//用户输入//------------------------------------------------------------------------------processInput(window);   //检测是否有输入//渲染指令//------------------------------------------------------------------------------glClearColor(0.2f, 0.3f, 0.3f, 1.0f);glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);//被投光物体//============================================================//激活着色器程序对象objectShader.use();objectShader.setVec3("light.position", lightPos);objectShader.setVec3("viewPos", camera.Position);//光照强度objectShader.setVec3("light.ambient", 0.2f, 0.2f, 0.2f);objectShader.setVec3("light.diffuse", 0.5f, 0.5f, 0.5f);objectShader.setVec3("light.specular", 1.0f, 1.0f, 1.0f);//材质objectShader.setVec3("material.specular", 0.5f, 0.5f, 0.5f);objectShader.setFloat("material.shininess", 64.0f);//创建变换矩阵glm::mat4 model = glm::mat4(1.0f);objectShader.setMat4("model", model);glm::mat4 view = camera.GetViewMatrix();objectShader.setMat4("view", view);glm::mat4 projection = glm::perspective(glm::radians(camera.Zoom), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);objectShader.setMat4("projection", projection);//绑定纹理glActiveTexture(GL_TEXTURE0);glBindTexture(GL_TEXTURE_2D, diffuseMap);//绘制三角形glBindVertexArray(objectVAO);             //绑定VAOglDrawArrays(GL_TRIANGLES, 0, 36);//============================================================//光源//============================================================//激活着色器程序对象lightShader.use();lightShader.setMat4("view", view);lightShader.setMat4("projection", projection);model = glm::mat4(1.0f);model = glm::translate(model, lightPos);model = glm::scale(model, glm::vec3(0.2f));lightShader.setMat4("model", model);//绘制三角形glBindVertexArray(lightVAO);             //绑定VAOglDrawArrays(GL_TRIANGLES, 0, 36);//============================================================//告诉GLFW检查所有等待处理的事件和消息，包括操作系统和窗口系统中应当处理的消息。如果有消息正在等待，它会先处理这些消息再返回；否则该函数会立即返回//---------------------------------------------------------------------------------------------------------------------------------glfwPollEvents();//请求窗口系统将参数window关联的后缓存画面呈现给用户(双缓冲绘图)//------------------------------------------------------------------------------glfwSwapBuffers(window);}//释放资源glDeleteVertexArrays(1, &objectVAO);glDeleteVertexArrays(1, &lightVAO);glDeleteBuffers(1, &VBO);//glDeleteProgram(objectShader);//glDeleteProgram(lightShader);//glfw销毁窗口和OpenGL环境，并释放资源（之后必须再次调用glfwInit()才能使用大多数GLFW函数）//------------------------------------------------------------------glfwTerminate();return a.exec();
}//检测是否有输入
//---------------------------------------------------------------------------------------------------------
void processInput(GLFWwindow *window)
{if(glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)   //ESC键，退出glfwSetWindowShouldClose(window, true);float cameraSpeed = static_cast<float>(2.5 * deltaTime);if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS)camera.ProcessKeyboard(FORWARD, deltaTime);if (glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS)camera.ProcessKeyboard(BACKWARD, deltaTime);if (glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS)camera.ProcessKeyboard(LEFT, deltaTime);if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS)camera.ProcessKeyboard(RIGHT, deltaTime);
}//给glfw窗口注册的尺寸改变回调函数
//---------------------------------------------------------------------------------------------
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{//确保视口匹配新的窗口尺寸，请注意：宽度和高度将比视网膜显示器上指定的大得多glViewport(0, 0, width, height);
}
// 鼠标移动时的回调函数
// -------------------------------------------------------
void mouse_callback(GLFWwindow* window, double xposIn, double yposIn)
{float xpos = static_cast<float>(xposIn);float ypos = static_cast<float>(yposIn);if (firstMouse){lastX = xpos;lastY = ypos;firstMouse = false;}float xoffset = lastX - xpos;float yoffset = ypos - lastY;   //翻转，因为Y轴是从下到上越来越大lastX = xpos;lastY = ypos;camera.ProcessMouseMovement(xoffset, yoffset);
}//鼠标滚轮的回调函数
// ----------------------------------------------------------------------
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
{camera.ProcessMouseScroll(static_cast<float>(yoffset));
}//从文件导入一个2D纹理
// ----------------------------------------------------------------------
unsigned int loadTexture(char const * path)
{unsigned int textureID;glGenTextures(1, &textureID);int width, height, nrComponents;unsigned char *data = stbi_load(path, &width, &height, &nrComponents, 0);if (data) {GLenum format;if (nrComponents == 1)format = GL_RED;else if (nrComponents == 3)format = GL_RGB;else if (nrComponents == 4)format = GL_RGBA;glBindTexture(GL_TEXTURE_2D, textureID);glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, format, GL_UNSIGNED_BYTE, data);glGenerateMipmap(GL_TEXTURE_2D);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);stbi_image_free(data);} else {std::cout << "Texture failed to load at path: " << path << std::endl;stbi_image_free(data);}return textureID;
}

---

三、镜面光贴图

你可能会注意到，镜面高光看起来有些奇怪，因为我们的物体大部分都是木头，我们知道木头不应该有这么强的镜面高光的。

我们可以将物体的镜面光材质设置为vec3(0.0)来解决这个问题，但这也意味着箱子钢制的边框将不再能够显示镜面高光了，我们知道钢铁应该是有一些镜面高光的。

所以，我们想要让物体的某些部分以不同的强度显示镜面高光。这个问题看起来和漫反射贴图非常相似。是巧合吗？我想不是。

我们同样可以使用一个专门用于镜面高光的纹理贴图。这也就意味着我们需要生成一个黑白的（如果你想得话也可以是彩色的）纹理，来定义物体每部分的镜面光强度。下面是一个镜面光贴图(Specular Map)的例子：

镜面高光的强度可以通过图像每个像素的亮度来获取。镜面光贴图上的每个像素都可以由一个颜色向量来表示，比如说黑色代表颜色向量vec3(0.0)，灰色代表颜色向量vec3(0.5)。

在片段着色器中，我们接下来会取样对应的颜色值并将它乘以光源的镜面强度。一个像素越「白」，乘积就会越大，物体的镜面光分量就会越亮。

由于箱子大部分都由木头所组成，而且木头材质应该没有镜面高光，所以漫反射纹理的整个木头部分全部都转换成了黑色。箱子钢制边框的镜面光强度是有细微变化的，钢铁本身会比较容易受到镜面高光的影响，而裂缝则不会。

从实际角度来说，木头其实也有镜面高光，尽管它的反光度(Shininess)很小（更多的光被散射），影响也比较小，但是为了教学目的，我们可以假设木头不会对镜面光有任何反应。

使用Photoshop或Gimp之类的工具，将漫反射纹理转换为镜面光纹理还是比较容易的，只需要剪切掉一些部分，将图像转换为黑白的，并增加亮度/对比度就好了。

---

3.1、采样镜面光贴图

镜面光贴图和其它的纹理非常类似，所以代码也和漫反射贴图的代码很类似。

记得要保证正确地加载图像并生成一个纹理对象。由于我们正在同一个片段着色器中使用另一个纹理采样器，我们必须要对镜面光贴图使用一个不同的纹理单元（见纹理），所以我们在渲染之前先把它绑定到合适的纹理单元上：

添加纹理

1、修改片段着色器，修改材质结构体-镜面光贴图，镜面反射光照中使用纹理

#version 330 corein vec3 FragPos;
in vec3 Normal;
in vec2 TexCoord;out vec4 FragColor;uniform vec3 viewPos;   //观察者坐标struct Material { //材质描述结构体sampler2D diffuse;  //漫反射贴图sampler2D specular; //镜面光贴图float shininess;    //反光度
};
uniform Material material;  //材质struct Light {  //光照强度vec3 position;vec3 ambient;vec3 diffuse;vec3 specular;
};
uniform Light light;void main()
{//环境光照vec3 ambient = light.ambient * vec3(texture(material.diffuse, TexCoord));//漫反射光照vec3 norm = normalize(Normal);vec3 lightDir = normalize(light.position - FragPos);float diff = max(dot(norm, lightDir), 0.0);vec3 diffuse = light.diffuse * diff * vec3(texture(material.diffuse, TexCoord));//镜面反射光照vec3 viewDir = normalize(viewPos - FragPos);vec3 reflectDir = reflect(-lightDir, norm);float spec = pow(max(dot(viewDir, reflectDir), 0.0), material.shininess);vec3 specular = light.specular * spec * vec3(texture(material.specular, TexCoord));vec3 result = ambient + diffuse + specular;FragColor = vec4(result, 1.0);
}

2、导入纹理

//创建纹理
//----------------------------------------------------------------
unsigned int diffuseMap = loadTexture("C:/Qt_Pro/OpenGL_GLFW/Sources/container2.png");
unsigned int specularMap = loadTexture("C:/Qt_Pro/OpenGL_GLFW/Sources/container2_specular.png");//赋值纹理
objectShader.use();
objectShader.setInt("material.diffuse", 0);
objectShader.setInt("material.specular", 1);

3、绑定纹理

//绑定纹理
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, diffuseMap);glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, specularMap);//绘制三角形
glBindVertexArray(objectVAO);             //绑定VAO
glDrawArrays(GL_TRIANGLES, 0, 36);

通过使用镜面光贴图我们可以可以对物体设置大量的细节，比如物体的哪些部分需要有闪闪发光的属性，我们甚至可以设置它们对应的强度。镜面光贴图能够在漫反射贴图之上给予我们更高一层的控制。

如果你现在运行程序的话，你可以清楚地看到箱子的材质现在和真实的钢制边框箱子非常类似了：

全部代码

被投光物体片段着色器

#version 330 corein vec3 FragPos;
in vec3 Normal;
in vec2 TexCoord;out vec4 FragColor;uniform vec3 viewPos;   //观察者坐标struct Material { //材质描述结构体sampler2D diffuse;  //漫反射贴图sampler2D specular; //镜面光贴图float shininess;    //反光度
};
uniform Material material;  //材质struct Light {  //光照强度vec3 position;vec3 ambient;vec3 diffuse;vec3 specular;
};
uniform Light light;void main()
{//环境光照vec3 ambient = light.ambient * vec3(texture(material.diffuse, TexCoord));//漫反射光照vec3 norm = normalize(Normal);vec3 lightDir = normalize(light.position - FragPos);float diff = max(dot(norm, lightDir), 0.0);vec3 diffuse = light.diffuse * diff * vec3(texture(material.diffuse, TexCoord));//镜面反射光照vec3 viewDir = normalize(viewPos - FragPos);vec3 reflectDir = reflect(-lightDir, norm);float spec = pow(max(dot(viewDir, reflectDir), 0.0), material.shininess);vec3 specular = light.specular * spec * vec3(texture(material.specular, TexCoord));vec3 result = ambient + diffuse + specular;FragColor = vec4(result, 1.0);
}

---

main.cpp

#include "mainwindow.h"
#include <QApplication>//在包含GLFW的头文件之前包含了GLAD的头文件;
//GLAD的头文件包含了正确的OpenGL头文件（例如GL/gl.h）;
//所以需要在其它依赖于OpenGL的头文件之前包含GLAD;
#include <glad/glad.h>
#include <GLFW/glfw3.h>//GLM
//#include <glm/glm.hpp>
//#include <glm/gtc/matrix_transform.hpp>
//#include <glm/gtc/type_ptr.hpp>#include <iostream>
#include <QDebug>#include "shader.h"
#include "stb_image.h"
#include "camera.h"void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void mouse_callback(GLFWwindow* window, double xposIn, double yposIn);
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
void processInput(GLFWwindow *window);
unsigned int loadTexture(char const * path);// settings
const unsigned int SCR_WIDTH = 1920;
const unsigned int SCR_HEIGHT = 1080;//Camera
Camera camera(glm::vec3(0.0f, 0.0f, 3.0f));
float lastX =  SCR_WIDTH / 2.0;
float lastY =  SCR_HEIGHT / 2.0;
bool firstMouse = true;float deltaTime = 0.0f; // 当前帧与上一帧的时间差
float lastFrame = 0.0f; // 上一帧的时间//Light
glm::vec3 lightPos(1.2f, 1.0f, 2.0f);using namespace std;int main(int argc, char *argv[])
{QApplication a(argc, argv);//MainWindow w;//w.show();//初始化GLFW//--------------------glfwInit();//配置GLFW//--------------------//告诉GLFW使用的OpenGL本是3.3glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);//告诉GLFW使用的是核心模式（Core-profile）glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);//创建一个新的OpenGL环境和窗口//-----------------------------------GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);if (window == NULL){std::cout << "Failed to create GLFW window" << std::endl;glfwTerminate();    //glfw销毁窗口和OpenGL环境，并释放资源return -1;}//设置参数window中的窗口所关联的OpenGL环境为当前环境//-----------------------------------glfwMakeContextCurrent(window);//设置窗口尺寸改变大小时的回调函数（窗口尺寸发送改变时会自动调用）//-----------------------------------glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);//设置鼠标事件的回调函数（鼠标移动时会自动调用）//-----------------------------------glfwSetCursorPosCallback(window, mouse_callback);//设置鼠标滚轮事件的回调函数（鼠标滚轮移动时会自动调用）//-----------------------------------glfwSetScrollCallback(window, scroll_callback);//告诉GLFW捕捉鼠标glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);//glad加载系统相关的OpenGL函数指针//---------------------------------------if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)){std::cout << "Failed to initialize GLAD" << std::endl;return -1;}//开启深度测试glEnable(GL_DEPTH_TEST);Shader objectShader("C:/Qt_Pro/OpenGL_GLFW/shader/shader.vs","C:/Qt_Pro/OpenGL_GLFW/shader/shader.fs");Shader lightShader("C:/Qt_Pro/OpenGL_GLFW/shader/light_cube.vs","C:/Qt_Pro/OpenGL_GLFW/shader/light_cube.fs");//顶点数据//---------------------------------------------------------------------float vertices[] = {//顶点坐标             //法线坐标            //纹理坐标-0.5f, -0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  0.0f,  0.0f,0.5f, -0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  1.0f,  0.0f,0.5f,  0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  1.0f,  1.0f,0.5f,  0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  1.0f,  1.0f,-0.5f,  0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  0.0f,  1.0f,-0.5f, -0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  0.0f,  0.0f,-0.5f, -0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  0.0f,  0.0f,0.5f, -0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  1.0f,  0.0f,0.5f,  0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  1.0f,  1.0f,0.5f,  0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  1.0f,  1.0f,-0.5f,  0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  0.0f,  1.0f,-0.5f, -0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  0.0f,  0.0f,-0.5f,  0.5f,  0.5f, -1.0f,  0.0f,  0.0f,  1.0f,  0.0f,-0.5f,  0.5f, -0.5f, -1.0f,  0.0f,  0.0f,  1.0f,  1.0f,-0.5f, -0.5f, -0.5f, -1.0f,  0.0f,  0.0f,  0.0f,  1.0f,-0.5f, -0.5f, -0.5f, -1.0f,  0.0f,  0.0f,  0.0f,  1.0f,-0.5f, -0.5f,  0.5f, -1.0f,  0.0f,  0.0f,  0.0f,  0.0f,-0.5f,  0.5f,  0.5f, -1.0f,  0.0f,  0.0f,  1.0f,  0.0f,0.5f,  0.5f,  0.5f,  1.0f,  0.0f,  0.0f,  1.0f,  0.0f,0.5f,  0.5f, -0.5f,  1.0f,  0.0f,  0.0f,  1.0f,  1.0f,0.5f, -0.5f, -0.5f,  1.0f,  0.0f,  0.0f,  0.0f,  1.0f,0.5f, -0.5f, -0.5f,  1.0f,  0.0f,  0.0f,  0.0f,  1.0f,0.5f, -0.5f,  0.5f,  1.0f,  0.0f,  0.0f,  0.0f,  0.0f,0.5f,  0.5f,  0.5f,  1.0f,  0.0f,  0.0f,  1.0f,  0.0f,-0.5f, -0.5f, -0.5f,  0.0f, -1.0f,  0.0f,  0.0f,  1.0f,0.5f, -0.5f, -0.5f,  0.0f, -1.0f,  0.0f,  1.0f,  1.0f,0.5f, -0.5f,  0.5f,  0.0f, -1.0f,  0.0f,  1.0f,  0.0f,0.5f, -0.5f,  0.5f,  0.0f, -1.0f,  0.0f,  1.0f,  0.0f,-0.5f, -0.5f,  0.5f,  0.0f, -1.0f,  0.0f,  0.0f,  0.0f,-0.5f, -0.5f, -0.5f,  0.0f, -1.0f,  0.0f,  0.0f,  1.0f,-0.5f,  0.5f, -0.5f,  0.0f,  1.0f,  0.0f,  0.0f,  1.0f,0.5f,  0.5f, -0.5f,  0.0f,  1.0f,  0.0f,  1.0f,  1.0f,0.5f,  0.5f,  0.5f,  0.0f,  1.0f,  0.0f,  1.0f,  0.0f,0.5f,  0.5f,  0.5f,  0.0f,  1.0f,  0.0f,  1.0f,  0.0f,-0.5f,  0.5f,  0.5f,  0.0f,  1.0f,  0.0f,  0.0f,  0.0f,-0.5f,  0.5f, -0.5f,  0.0f,  1.0f,  0.0f,  0.0f,  1.0f};//物体//----------------------------------------------------------------unsigned int VBO, objectVAO;glGenVertexArrays(1, &objectVAO);     //创建顶点数组对象glGenBuffers(1, &VBO);          //创建顶点缓冲对象glBindBuffer(GL_ARRAY_BUFFER, VBO);     //将VBO与GL_ARRAY_BUFFER缓冲区绑定glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);  //将顶点数据复制到GL_ARRAY_BUFFER缓冲区，之后可通过VBO进行操作glBindVertexArray(objectVAO);         //绑定VAO//设定顶点属性指针//位置属性glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);glEnableVertexAttribArray(0);//法向量属性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);//光源(VBO用上面的)//----------------------------------------------------------------unsigned int lightVAO;glGenVertexArrays(1, &lightVAO);     //创建顶点数组对象glBindVertexArray(lightVAO);         //绑定VAOglBindBuffer(GL_ARRAY_BUFFER, VBO);     //将VBO与GL_ARRAY_BUFFER缓冲区绑定glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);glEnableVertexAttribArray(0);//创建纹理//----------------------------------------------------------------unsigned int diffuseMap = loadTexture("C:/Qt_Pro/OpenGL_GLFW/Sources/container2.png");unsigned int specularMap = loadTexture("C:/Qt_Pro/OpenGL_GLFW/Sources/container2_specular.png");//赋值纹理objectShader.use();objectShader.setInt("material.diffuse", 0);objectShader.setInt("material.specular", 1);//渲染循环//我们可不希望只绘制一个图像之后我们的应用程序就立即退出并关闭窗口;//我们希望程序在我们主动关闭它之前不断绘制图像并能够接受用户输入;//因此，我们需要在程序中添加一个while循环，它能在我们让GLFW退出前一直保持运行;//------------------------------------------------------------------------------while (!glfwWindowShouldClose(window))  //如果用户准备关闭参数window所指定的窗口，那么此接口将会返回GL_TRUE，否则将会返回GL_FALSE{//更新时间差float currentFrame = static_cast<float>(glfwGetTime());deltaTime = currentFrame - lastFrame;lastFrame = currentFrame;//用户输入//------------------------------------------------------------------------------processInput(window);   //检测是否有输入//渲染指令//------------------------------------------------------------------------------glClearColor(0.2f, 0.3f, 0.3f, 1.0f);glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);//被投光物体//============================================================//激活着色器程序对象objectShader.use();objectShader.setVec3("light.position", lightPos);objectShader.setVec3("viewPos", camera.Position);//光照强度objectShader.setVec3("light.ambient", 0.2f, 0.2f, 0.2f);objectShader.setVec3("light.diffuse", 0.5f, 0.5f, 0.5f);objectShader.setVec3("light.specular", 1.0f, 1.0f, 1.0f);//材质objectShader.setFloat("material.shininess", 64.0f);//创建变换矩阵glm::mat4 model = glm::mat4(1.0f);objectShader.setMat4("model", model);glm::mat4 view = camera.GetViewMatrix();objectShader.setMat4("view", view);glm::mat4 projection = glm::perspective(glm::radians(camera.Zoom), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);objectShader.setMat4("projection", projection);//绑定纹理glActiveTexture(GL_TEXTURE0);glBindTexture(GL_TEXTURE_2D, diffuseMap);glActiveTexture(GL_TEXTURE1);glBindTexture(GL_TEXTURE_2D, specularMap);//绘制三角形glBindVertexArray(objectVAO);             //绑定VAOglDrawArrays(GL_TRIANGLES, 0, 36);//============================================================//光源//============================================================//激活着色器程序对象lightShader.use();lightShader.setMat4("view", view);lightShader.setMat4("projection", projection);model = glm::mat4(1.0f);model = glm::translate(model, lightPos);model = glm::scale(model, glm::vec3(0.2f));lightShader.setMat4("model", model);//绘制三角形glBindVertexArray(lightVAO);             //绑定VAOglDrawArrays(GL_TRIANGLES, 0, 36);//============================================================//告诉GLFW检查所有等待处理的事件和消息，包括操作系统和窗口系统中应当处理的消息。如果有消息正在等待，它会先处理这些消息再返回；否则该函数会立即返回//---------------------------------------------------------------------------------------------------------------------------------glfwPollEvents();//请求窗口系统将参数window关联的后缓存画面呈现给用户(双缓冲绘图)//------------------------------------------------------------------------------glfwSwapBuffers(window);}//释放资源glDeleteVertexArrays(1, &objectVAO);glDeleteVertexArrays(1, &lightVAO);glDeleteBuffers(1, &VBO);//glDeleteProgram(objectShader);//glDeleteProgram(lightShader);//glfw销毁窗口和OpenGL环境，并释放资源（之后必须再次调用glfwInit()才能使用大多数GLFW函数）//------------------------------------------------------------------glfwTerminate();return a.exec();
}//检测是否有输入
//---------------------------------------------------------------------------------------------------------
void processInput(GLFWwindow *window)
{if(glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)   //ESC键，退出glfwSetWindowShouldClose(window, true);float cameraSpeed = static_cast<float>(2.5 * deltaTime);if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS)camera.ProcessKeyboard(FORWARD, deltaTime);if (glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS)camera.ProcessKeyboard(BACKWARD, deltaTime);if (glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS)camera.ProcessKeyboard(LEFT, deltaTime);if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS)camera.ProcessKeyboard(RIGHT, deltaTime);
}//给glfw窗口注册的尺寸改变回调函数
//---------------------------------------------------------------------------------------------
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{//确保视口匹配新的窗口尺寸，请注意：宽度和高度将比视网膜显示器上指定的大得多glViewport(0, 0, width, height);
}
// 鼠标移动时的回调函数
// -------------------------------------------------------
void mouse_callback(GLFWwindow* window, double xposIn, double yposIn)
{float xpos = static_cast<float>(xposIn);float ypos = static_cast<float>(yposIn);if (firstMouse){lastX = xpos;lastY = ypos;firstMouse = false;}float xoffset = lastX - xpos;float yoffset = ypos - lastY;   //翻转，因为Y轴是从下到上越来越大lastX = xpos;lastY = ypos;camera.ProcessMouseMovement(xoffset, yoffset);
}//鼠标滚轮的回调函数
// ----------------------------------------------------------------------
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
{camera.ProcessMouseScroll(static_cast<float>(yoffset));
}//从文件导入一个2D纹理
// ----------------------------------------------------------------------
unsigned int loadTexture(char const * path)
{unsigned int textureID;glGenTextures(1, &textureID);int width, height, nrComponents;unsigned char *data = stbi_load(path, &width, &height, &nrComponents, 0);if (data) {GLenum format;if (nrComponents == 1)format = GL_RED;else if (nrComponents == 3)format = GL_RGB;else if (nrComponents == 4)format = GL_RGBA;glBindTexture(GL_TEXTURE_2D, textureID);glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, format, GL_UNSIGNED_BYTE, data);glGenerateMipmap(GL_TEXTURE_2D);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);stbi_image_free(data);} else {std::cout << "Texture failed to load at path: " << path << std::endl;stbi_image_free(data);}return textureID;
}

通过使用漫反射和镜面光贴图，我们可以给相对简单的物体添加大量的细节。我们甚至可以使用法线/凹凸贴图(Normal/Bump Map)或者反射贴图(Reflection Map)给物体添加更多的细节，但这些将会留到之后的教程中。