OpenGL学习日记之光照计算

引言

现实生活中的光照极其复杂，而且会收到很多因素的影响，是我们当前计算机的算力无法模拟的。因此我们会根据一些简化的模型来模拟现实光照，这样在可以模拟出近似的光照感受，但是又没有那么复杂的计算。
常用的光照模型有：兰伯特光照模型（主要是模拟漫反射），半兰伯特光照模型（调优兰伯特全黑的缺点），Phong光照模型（模拟镜面反射），BlinnPhong光照模型（兰伯特+Phong）等

Phong光照模型

从模拟光照的角度，我们主要有3种光照：环境光、漫反射光照、镜面反射。

环境光
现实生活中，光照通常来自于多个光源，并且会在多个物体之间发散和反弹，一个物体的光照可能受到来自一个非直射的光源影响，最后才进入人眼，也就是所谓的间接光照。考虑到这种情况的算法叫做全局照明(Global Illumination)算法，但是这种算法既开销高昂又极其复杂。
所以我们将会使用一种简化的全局照明模型，叫做环境光照(Ambient Lighting)。我们使用一个很小的常量(光)颜色添加进物体片段的最终颜色里，这看起来就像即使没有直射光源也始终存在着一些发散的光。

漫反射光
光线照在粗糙物体表面，随机散射到各个方向，漫反射中视角的位置是不重要的，因为反射是完全随机的，所以在任何反射方向都是随机的。我们需要测量这个光线与它所接触片段之间的角度。如果光线垂直于物体表面，这束光对物体的影响会最大。

镜面反射
是光线经过物体表面，反射到视野中，当反射光线与人的眼睛看得方向平行时，强度最大，高光效果最明显，夹角为90度时，强度最小。

光源类型

定向光（平行光）

当一个光源很远的时候，来自光源的每条光线接近于平行。这看起来就像所有的光线来自于同一个方向，无论物体和观察者在哪儿。当一个光源被设置为无限远时，它被称为定向光(Directional Light)，因为所有的光线都有着同一个方向；它会独立于光源的位置。
我们知道的定向光源的一个好例子是，太阳。太阳和我们不是无限远，但它也足够远了，在计算光照的时候，我们感觉它就像无限远。在下面的图片里，来自于太阳的所有的光线都被定义为平行光，如下图所示：

点光源

某一个位置发出的光源，并且该光照强度会根据距离该光源的位置发生变化，距离光源位置越远，光照越弱，光照会随着距离发生衰减。衰减如下图所示

聚光灯

聚光是一种位于环境中某处的光源，它不是向所有方向照射，而是只朝某个方向照射。结果是只有一个聚光照射方向的确定半径内的物体才会被照亮，其他的都保持黑暗。
聚光的好例子是路灯或手电筒，OpenGL中的聚光用世界空间位置，一个方向和一个指定了聚光半径的切光角来表示。我们计算的每个片段，如果片段在聚光的切光方向之间（就是在圆锥体内），我们就会把片段照亮。如下图所示：

Phong光照模型GLSL代码

顶点着色器代码

脚本：VertexShaderSource2_1_1.txt

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

片段着色器代码

脚本：FragmentShaderSource2_1_1.txt

#version 330 core
out vec4 color;//片段UV坐标
in vec2 TexCoords;
//片段世界空间位置坐标
in vec3 FragPos;  
//片段世界空间法线
in vec3 Normal; struct Material
{vec3 ambient;//漫反射贴图sampler2D diffuse;//镜面反射贴图sampler2D specular;//镜面反射系数float shininess;
};//平行光封装结构体
struct DirLight {vec3 direction;vec3 ambient;vec3 diffuse;vec3 specular;
};//点光源封装结构体
struct PointLight {vec3 position;float constant;float linear;float quadratic;  vec3 ambient;vec3 diffuse;vec3 specular;
};//聚光灯封装结构体
struct SpotLight {vec3 ambient;vec3 diffuse;vec3 specular;//衰减参数float constant;float linear;float quadratic;vec3 position;vec3 direction;//内部切光角float cutOff;//外部切光角float outerCutOff;
};//观察者位置坐标
uniform vec3 viewPos;
uniform Material material;uniform DirLight dirLight;
uniform SpotLight spotLight;
#define NR_POINT_LIGHTS 4  
uniform PointLight pointLights[NR_POINT_LIGHTS];vec3 CalcDirLight(DirLight light, vec3 normal, vec3 viewDir);
vec3 CalcPointLight(PointLight light, vec3 normal, vec3 fragPos, vec3 viewDir);
vec3 CalcSpotLight(SpotLight light, vec3 noraml, vec3 fragPos, vec3 viewDir);void main()
{    vec3 norm = normalize(Normal);vec3 viewDir = normalize(viewPos - FragPos);// 第一步，计算平行光照vec3 result = CalcDirLight(dirLight, norm, viewDir);// 第二步，计算点光源光照for(int i = 0; i < NR_POINT_LIGHTS; i++)result += CalcPointLight(pointLights[i], norm, FragPos, viewDir);// 第三部，计算聚光灯光照//result += CalcSpotLight(spotLight, norm, FragPos, viewDir);color = vec4(result, 1.0);
}vec3 CalcDirLight(DirLight light,vec3 normal,vec3 viewDir)
{vec3 lightDir = normalize(-light.direction);float diff = max(dot(normal, lightDir), 0.0);vec3 reflectDir = reflect(-lightDir, normal); 	float spec = pow(max(dot(viewDir, reflectDir), 0.0f), material.shininess);vec3 ambient = light.ambient * vec3 (texture(material.diffuse,TexCoords));vec3 diffuse  = light.diffuse  * diff * vec3(texture(material.diffuse, TexCoords));vec3 specular = light.specular * spec * vec3(texture(material.specular, TexCoords));return (ambient + diffuse + specular);
}vec3 CalcPointLight(PointLight light, vec3 normal, vec3 fragPos, vec3 viewDir)
{vec3 lightDir=normalize(light.position-fragPos);float diff=max(dot(lightDir,normal),0.0f);vec3 reflectDir=reflect(-lightDir,normal);float spec=pow(max(dot(viewDir,reflectDir),0.0f),material.shininess);float distance=length(light.position-fragPos);float attenuation=1.0f/(light.constant+light.linear*distance+light.quadratic*distance*distance);vec3 ambient = light.ambient * vec3(texture(material.diffuse,TexCoords));vec3 diffuse  = light.diffuse  * diff * vec3(texture(material.diffuse, TexCoords));vec3 specular = light.specular * spec * vec3(texture(material.specular, TexCoords));ambient  *= attenuation;diffuse  *= attenuation;specular *= attenuation;return (ambient + diffuse + specular);
}vec3 CalcSpotLight(SpotLight light, vec3 noraml, vec3 fragPos, vec3 viewDir)
{vec3 lightDir=normalize(light.position-fragPos);float theta = dot(lightDir, normalize(-light.direction));float epsilon = light.cutOff - light.outerCutOff;float intensity = clamp((theta - light.outerCutOff) / epsilon,0.0, 1.0);float diff=max(dot(lightDir,noraml),0.0f);vec3 reflectDir=reflect(-lightDir,noraml);float spec=pow(max(dot(viewDir,reflectDir),0.0f),material.shininess);float distance=length(light.position-fragPos);float attenuation=1.0f/(light.constant+light.linear*distance+light.quadratic*distance*distance);vec3 ambient = light.ambient * vec3(texture(material.diffuse,TexCoords));vec3 diffuse  = light.diffuse  * diff * vec3(texture(material.diffuse, TexCoords));vec3 specular = light.specular * spec * vec3(texture(material.specular, TexCoords));ambient  *= attenuation;diffuse  *= attenuation;specular *= attenuation;diffuse  *= intensity;specular *= intensity;return (ambient + diffuse + specular);
}

渲染流程代码

GLSL渲染代码

#include <iostream>
#include <cmath>// GLEW
#define GLEW_STATIC
#include <GL/glew.h>// GLFW
#include <GLFW/glfw3.h>// Other Libs
#include <SOIL.h>
// GLM Mathematics
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>// Other includes
#include "Shader.h"// Function prototypes
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode);
void mouse_callback(GLFWwindow* window, double xpos, double ypos);
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
void do_movement();// Window dimensions
const GLuint WIDTH = 800, 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);
GLfloat yaw = -90.0f;	// Yaw is initialized to -90.0 degrees since a yaw of 0.0 results in a direction vector pointing to the right (due to how Eular angles work) so we initially rotate a bit to the left.
GLfloat pitch = 0.0f;
GLfloat lastX = WIDTH / 2.0;
GLfloat lastY = HEIGHT / 2.0;
bool keys[1024];// Light attributes
glm::vec3 lightPos(1.2f, 1.0f, 2.0f);// Deltatime
GLfloat deltaTime = 0.0f;	// Time between current frame and last frame
GLfloat lastFrame = 0.0f;  	// Time of last frame// The MAIN function, from here we start the application and run the game loop
int main()
{// Init GLFWglfwInit();// Set all the required options for GLFWglfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);// Create a GLFWwindow object that we can use for GLFW's functionsGLFWwindow* window = glfwCreateWindow(WIDTH, HEIGHT, "LearnOpenGL", nullptr, nullptr);glfwMakeContextCurrent(window);// Set the required callback functionsglfwSetKeyCallback(window, key_callback);glfwSetCursorPosCallback(window, mouse_callback);glfwSetScrollCallback(window, scroll_callback);// GLFW OptionsglfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);// Set this to true so GLEW knows to use a modern approach to retrieving function pointers and extensionsglewExperimental = GL_TRUE;// Initialize GLEW to setup the OpenGL Function pointersglewInit();// Define the viewport dimensionsglViewport(0, 0, WIDTH, HEIGHT);// OpenGL optionsglEnable(GL_DEPTH_TEST);// Build and compile our shader programShader lightingShader("VertexShaderSource2_1_1.txt", "FragmentShaderSource2_1_1.txt");Shader lampShader("VertexShaderSource1_7_1.txt", "FragmentShaderSource1_7_1.txt");// Set up vertex data (and buffer(s)) and attribute pointers// Set up vertex data (and buffer(s)) and attribute pointersGLfloat vertices[] = {// Positions          // Normals           // Texture Coords-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};// Positions all containersglm::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)};// Positions of the point lightsglm::vec3 pointLightPositions[] = {glm::vec3(0.7f,  0.2f,  2.0f),glm::vec3(2.3f, -3.3f, -4.0f),glm::vec3(-4.0f,  2.0f, -12.0f),glm::vec3(0.0f,  0.0f, -3.0f)};// First, set the container's VAO (and VBO)GLuint VBO, containerVAO;glGenVertexArrays(1, &containerVAO);glGenBuffers(1, &VBO);glBindBuffer(GL_ARRAY_BUFFER, VBO);glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);glBindVertexArray(containerVAO);glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)0);glEnableVertexAttribArray(0);glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));glEnableVertexAttribArray(1);glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)(6 * sizeof(GLfloat)));glEnableVertexAttribArray(2);glBindVertexArray(0);// Then, we set the light's VAO (VBO stays the same. After all, the vertices are the same for the light object (also a 3D cube))GLuint lightVAO;glGenVertexArrays(1, &lightVAO);glBindVertexArray(lightVAO);// We only need to bind to the VBO (to link it with glVertexAttribPointer), no need to fill it; the VBO's data already contains all we need.glBindBuffer(GL_ARRAY_BUFFER, VBO);// Set the vertex attributes (only position data for the lamp))glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)0); // Note that we skip over the other data in our buffer object (we don't need the normals/textures, only positions).glEnableVertexAttribArray(0);glBindVertexArray(0);// Load texturesGLuint diffuseMap;glGenTextures(1, &diffuseMap);int width, height;unsigned char* image;// Diffuse mapimage = SOIL_load_image("container2.png", &width, &height, 0, SOIL_LOAD_RGB);glBindTexture(GL_TEXTURE_2D, diffuseMap);glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image);glGenerateMipmap(GL_TEXTURE_2D);SOIL_free_image_data(image);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_NEAREST_MIPMAP_NEAREST);GLuint specularMap;glGenTextures(1, &specularMap);image = SOIL_load_image("container2_specular.png", &width, &height, 0, SOIL_LOAD_RGB);glBindTexture(GL_TEXTURE_2D, specularMap);glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image);glGenerateMipmap(GL_TEXTURE_2D);SOIL_free_image_data(image);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_NEAREST_MIPMAP_NEAREST);glBindTexture(GL_TEXTURE_2D, 0);lightingShader.Use();glUniform1i(glGetUniformLocation(lightingShader.Program, "material.diffuse"), 0);glUniform1i(glGetUniformLocation(lightingShader.Program, "material.specular"), 1);// Game loopwhile (!glfwWindowShouldClose(window)){// Calculate deltatime of current frameGLfloat currentFrame = glfwGetTime();deltaTime = currentFrame - lastFrame;lastFrame = currentFrame;// Check if any events have been activiated (key pressed, mouse moved etc.) and call corresponding response functionsglfwPollEvents();do_movement();// Clear the colorbufferglClearColor(0.1f, 0.1f, 0.1f, 1.0f);glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);// Use cooresponding shader when setting uniforms/drawing objectslightingShader.Use();    glUniform3f(glGetUniformLocation(lightingShader.Program, "viewPos"), cameraPos.x, cameraPos.y, cameraPos.z);glUniform1f(glGetUniformLocation(lightingShader.Program, "material.shininess"), 64.0f);     glUniform3f(glGetUniformLocation(lightingShader.Program, "dirLight.direction"), -0.2f, -1.0f, -0.3f);glUniform3f(glGetUniformLocation(lightingShader.Program, "dirLight.ambient"), 0.05f, 0.05f, 0.05f);glUniform3f(glGetUniformLocation(lightingShader.Program, "dirLight.diffuse"), 0.4f, 0.4f, 0.4f);glUniform3f(glGetUniformLocation(lightingShader.Program, "dirLight.specular"), 0.5f, 0.5f, 0.5f);// Point light 1glUniform3f(glGetUniformLocation(lightingShader.Program, "pointLights[0].position"), pointLightPositions[0].x, pointLightPositions[0].y, pointLightPositions[0].z);glUniform3f(glGetUniformLocation(lightingShader.Program, "pointLights[0].ambient"), 0.05f, 0.05f, 0.05f);glUniform3f(glGetUniformLocation(lightingShader.Program, "pointLights[0].diffuse"), 0.8f, 0.8f, 0.8f);glUniform3f(glGetUniformLocation(lightingShader.Program, "pointLights[0].specular"), 1.0f, 1.0f, 1.0f);glUniform1f(glGetUniformLocation(lightingShader.Program, "pointLights[0].constant"), 1.0f);glUniform1f(glGetUniformLocation(lightingShader.Program, "pointLights[0].linear"), 0.09f);glUniform1f(glGetUniformLocation(lightingShader.Program, "pointLights[0].quadratic"), 0.032f);// Point light 2glUniform3f(glGetUniformLocation(lightingShader.Program, "pointLights[1].position"), pointLightPositions[1].x, pointLightPositions[1].y, pointLightPositions[1].z);glUniform3f(glGetUniformLocation(lightingShader.Program, "pointLights[1].ambient"), 0.05f, 0.05f, 0.05f);glUniform3f(glGetUniformLocation(lightingShader.Program, "pointLights[1].diffuse"), 0.8f, 0.8f, 0.8f);glUniform3f(glGetUniformLocation(lightingShader.Program, "pointLights[1].specular"), 1.0f, 1.0f, 1.0f);glUniform1f(glGetUniformLocation(lightingShader.Program, "pointLights[1].constant"), 1.0f);glUniform1f(glGetUniformLocation(lightingShader.Program, "pointLights[1].linear"), 0.09f);glUniform1f(glGetUniformLocation(lightingShader.Program, "pointLights[1].quadratic"), 0.032f);// Point light 3glUniform3f(glGetUniformLocation(lightingShader.Program, "pointLights[2].position"), pointLightPositions[2].x, pointLightPositions[2].y, pointLightPositions[2].z);glUniform3f(glGetUniformLocation(lightingShader.Program, "pointLights[2].ambient"), 0.05f, 0.05f, 0.05f);glUniform3f(glGetUniformLocation(lightingShader.Program, "pointLights[2].diffuse"), 0.8f, 0.8f, 0.8f);glUniform3f(glGetUniformLocation(lightingShader.Program, "pointLights[2].specular"), 1.0f, 1.0f, 1.0f);glUniform1f(glGetUniformLocation(lightingShader.Program, "pointLights[2].constant"), 1.0f);glUniform1f(glGetUniformLocation(lightingShader.Program, "pointLights[2].linear"), 0.09f);glUniform1f(glGetUniformLocation(lightingShader.Program, "pointLights[2].quadratic"), 0.032f);// Point light 4glUniform3f(glGetUniformLocation(lightingShader.Program, "pointLights[3].position"), pointLightPositions[3].x, pointLightPositions[3].y, pointLightPositions[3].z);glUniform3f(glGetUniformLocation(lightingShader.Program, "pointLights[3].ambient"), 0.05f, 0.05f, 0.05f);glUniform3f(glGetUniformLocation(lightingShader.Program, "pointLights[3].diffuse"), 0.8f, 0.8f, 0.8f);glUniform3f(glGetUniformLocation(lightingShader.Program, "pointLights[3].specular"), 1.0f, 1.0f, 1.0f);glUniform1f(glGetUniformLocation(lightingShader.Program, "pointLights[3].constant"), 1.0f);glUniform1f(glGetUniformLocation(lightingShader.Program, "pointLights[3].linear"), 0.09f);glUniform1f(glGetUniformLocation(lightingShader.Program, "pointLights[3].quadratic"), 0.032f);glUniform3f(glGetUniformLocation(lightingShader.Program, "spotLight.ambient"), 0.8f, 0.8f, 0.8f);glUniform3f(glGetUniformLocation(lightingShader.Program, "spotLight.diffuse"), 0.8f, 0.8f, 0.8f);glUniform3f(glGetUniformLocation(lightingShader.Program, "spotLight.specular"), 1.0f, 1.0f, 1.0f);glUniform1f(glGetUniformLocation(lightingShader.Program, "spotLight.constant"), 1.0f);glUniform1f(glGetUniformLocation(lightingShader.Program, "spotLight.linear"), 0.09);glUniform1f(glGetUniformLocation(lightingShader.Program, "spotLight.quadratic"), 0.032);glUniform3f(glGetUniformLocation(lightingShader.Program, "spotLight.position"), cameraPos.x, cameraPos.y, cameraPos.z);glUniform3f(glGetUniformLocation(lightingShader.Program, "spotLight.direction"), cameraFront.x, cameraFront.y, cameraFront.z);glUniform1f(glGetUniformLocation(lightingShader.Program, "spotLight.cutOff"), glm::cos(glm::radians(12.5f)));glUniform1f(glGetUniformLocation(lightingShader.Program, "spotLight.outerCutOff"), glm::cos(glm::radians(17.5f)));// Create camera transformationsglm::mat4 view(1);glm::mat4 model(1);glm::mat4 projection(1);     view = glm::lookAt(cameraPos, cameraPos + cameraFront, cameraUp);projection = glm::perspective(45.0f, (GLfloat)WIDTH / (GLfloat)HEIGHT, 0.1f, 100.0f);// Get the uniform locationsGLint modelLoc = glGetUniformLocation(lightingShader.Program, "model");GLint viewLoc = glGetUniformLocation(lightingShader.Program, "view");GLint projLoc = glGetUniformLocation(lightingShader.Program, "projection");// Pass the matrices to the        glUniformMatrix4fv(viewLoc, 1, GL_FALSE, glm::value_ptr(view));glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(projection));// Bind diffuse mapglActiveTexture(GL_TEXTURE0);glBindTexture(GL_TEXTURE_2D, diffuseMap);// Bind specular mapglActiveTexture(GL_TEXTURE1);glBindTexture(GL_TEXTURE_2D, specularMap);// Draw the container (using container's vertex attributes)glBindVertexArray(containerVAO);for (GLuint i = 0; i < 10; i++){model = glm::mat4(1);model = glm::translate(model, cubePositions[i]);GLfloat angle = 20.0f * i;model = glm::rotate(model, angle, glm::vec3(1.0f, 0.3f, 0.5f));glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));glDrawArrays(GL_TRIANGLES, 0, 36);}glBindVertexArray(0);  lampShader.Use();// Get location objects for the matrices on the lamp shader (these could be different on a different shader)modelLoc = glGetUniformLocation(lampShader.Program, "model");viewLoc = glGetUniformLocation(lampShader.Program, "view");projLoc = glGetUniformLocation(lampShader.Program, "projection");// Set matricesglUniformMatrix4fv(viewLoc, 1, GL_FALSE, glm::value_ptr(view));glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(projection));// We now draw as many light bulbs as we have point lights.glBindVertexArray(lightVAO);for (GLuint i = 0; i < 4; i++){model = glm::mat4(1);model = glm::translate(model, pointLightPositions[i]);model = glm::scale(model, glm::vec3(0.2f)); // Make it a smaller cubeglUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));glDrawArrays(GL_TRIANGLES, 0, 36);}glBindVertexArray(0);// Swap the screen buffersglfwSwapBuffers(window);}// Terminate GLFW, clearing any resources allocated by GLFW.glfwTerminate();return 0;
}// Is called whenever a key is pressed/released via GLFW
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode)
{if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)glfwSetWindowShouldClose(window, GL_TRUE);if (key >= 0 && key < 1024){if (action == GLFW_PRESS)keys[key] = true;else if (action == GLFW_RELEASE)keys[key] = false;}
}void do_movement()
{// Camera controlsGLfloat cameraSpeed = 5.0f * deltaTime;if (keys[GLFW_KEY_W])cameraPos += cameraSpeed * cameraFront;if (keys[GLFW_KEY_S])cameraPos -= cameraSpeed * cameraFront;if (keys[GLFW_KEY_A])cameraPos -= glm::normalize(glm::cross(cameraFront, cameraUp)) * cameraSpeed;if (keys[GLFW_KEY_D])cameraPos += glm::normalize(glm::cross(cameraFront, cameraUp)) * cameraSpeed;
}bool firstMouse = true;
void mouse_callback(GLFWwindow* window, double xpos, double ypos)
{if (firstMouse){lastX = xpos;lastY = ypos;firstMouse = false;}GLfloat xoffset = xpos - lastX;GLfloat yoffset = lastY - ypos; // Reversed since y-coordinates go from bottom to leftlastX = xpos;lastY = ypos;GLfloat sensitivity = 0.05;	// Change this value to your likingxoffset *= sensitivity;yoffset *= sensitivity;yaw += xoffset;pitch += yoffset;// Make sure that when pitch is out of bounds, screen doesn't get flippedif (pitch > 89.0f)pitch = 89.0f;if (pitch < -89.0f)pitch = -89.0f;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);}void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
{}

参考链接：https://www.yumefx.com/?p=3006
参考链接：https://learnopengl-cn.readthedocs.io/zh/latest/02%20Lighting/06%20Multiple%20lights/