OpenGL_Learn12（光照）-编程知识

续OpenGL_Learn11（光照）-CSDN博客

1. 镜面高光

和漫反射光照一样，镜面光照也决定于光的方向向量和物体的法向量，但是它也决定于观察方向，例如玩家是从什么方向看向这个片段的。镜面光照决定于表面的反射特性。

我们通过根据法向量翻折入射光的方向来计算反射向量（对称就是R那条线）。然后我们计算反射向量与观察方向的角度差，它们之间夹角越小，镜面光的作用就越大。由此产生的效果就是，我们看向在入射光在表面的反射方向时，会看到一点高光。

只需要修改

cube.vs

增加翻折后的法向量

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

cube.fs

增加一个高光因子

#version 330 core
out vec4 FragColor;in vec3 Normal;
in vec3 FragPos;uniform vec3 objectColor;
uniform vec3 lightColor;
uniform vec3 lightPos;
uniform vec3 viewPos;void main()
{//ambientfloat ambientStrength=0.1;vec3 ambient=ambientStrength*lightColor;//diffusevec3 norm=normalize(Normal);vec3 lightDir=normalize(lightPos-FragPos);//光的方向向量是光源位置向量与片段位置向量之间的向量差。//对norm和lightDir向量进行点乘，计算光源对当前片段实际的漫反射影响//两个向量之间的角度越大，漫反射分量就会越小，点乘的几何意义也如此float diff=max(dot(norm,lightDir),0.0);vec3 diffuse=diff*lightColor;//specularfloat specularStrength=0.5;//高光强度//漫反射是光源指向片段位置。现在这个是摄像机指向片段位置vec3 viewDir=normalize(viewPos-FragPos);vec3 reflectDir=reflect(-lightDir,norm);//reflect第一个参数就是要片段指向摄像机位置float spec=pow(max(dot(viewDir,reflectDir),0.0),32);vec3 specular=specularStrength*spec*lightColor;vec3 result=(ambient+diffuse+specular)*objectColor;FragColor = vec4(result, 1.0);
}

main.cpp

#include <glad/glad.h>
#include <GLFW/glfw3.h>#include <iostream>
#include "stb_image.h"
#include <cmath>
#include "shader.h"
#include "camera.h"#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void processInput(GLFWwindow* window);
void mouse_callback(GLFWwindow* window, double xpos, double ypos);
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);// settings
const unsigned int SCR_WIDTH = 1800;
const unsigned int SCR_HEIGHT = 1200;//camera
Camera camera(glm::vec3(0.0f, 0.0f, 3.0f));
float lastX = SCR_WIDTH / 2.0f;
float lastY = SCR_HEIGHT / 2.0f;
bool firstMouse = true;//timing
float deltaTime = 0.0f;//不同配置绘制速度不同，所以需要这个属性
float lastFrame = 0.0f;//lighting
glm::vec3 lightPos(1.2f, 1.0f, 2.0f);int main() {//glfw:initialize and configure//=============================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 window creation//=============================GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "Learn", NULL, NULL);if (window == NULL) {std::cout << "Failed to create GLFW window" << std::endl;glfwTerminate();return -1;}glfwMakeContextCurrent(window);glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);glfwSetCursorPosCallback(window, mouse_callback);glfwSetScrollCallback(window, scroll_callback);//tell GLFW to capture our mouseglfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);//glad::load all OPenGL function pointers//=============================if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {std::cout << "Failed to initialize GLAD" << std::endl;return -1;}//configure gloabl opengl state//=============================glEnable(GL_DEPTH_TEST);//build and compile our shader zprogram//=============================Shader lightingShader("./cube.vs", "./cube.fs");Shader lightingCubeShader("./light_cube.vs", "./light_cube.fs");//set up vertex data float vertices[] = {-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};//第一个unsigned int VBO, cubeVAO;glGenVertexArrays(1, &cubeVAO);glGenBuffers(1, &VBO);glBindBuffer(GL_ARRAY_BUFFER, VBO);glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);glBindVertexArray(cubeVAO);//position attributeglVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);glEnableVertexAttribArray(0);//normal attributeglVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float)));glEnableVertexAttribArray(1);//第二个unsigned int lightCubeVAO;glGenVertexArrays(1, &lightCubeVAO);glBindVertexArray(lightCubeVAO);glBindBuffer(GL_ARRAY_BUFFER, VBO);glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);glEnableVertexAttribArray(0);// render loop// -----------while (!glfwWindowShouldClose(window)){// per-frame time logic// --------------------float currentFrame = static_cast<float>(glfwGetTime());deltaTime = currentFrame - lastFrame;lastFrame = currentFrame;// input// -----processInput(window);// render// ------glClearColor(0.1f, 0.1f, 0.1f, 1.0f);glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);// be sure to activate shader when setting uniforms/drawing objectslightingShader.use();lightingShader.setVec3("objectColor", 1.0f, 0.5f, 0.31f);lightingShader.setVec3("lightColor", 1.0f, 1.0f, 1.0f);lightingShader.setVec3("lightPos", lightPos);lightingShader.setVec3("viewPos", camera.Position);// view/projection transformationsglm::mat4 projection = glm::perspective(glm::radians(camera.Zoom), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);glm::mat4 view = camera.GetViewMatrix();lightingShader.setMat4("projection", projection);lightingShader.setMat4("view", view);// world transformationglm::mat4 model = glm::mat4(1.0f);lightingShader.setMat4("model", model);// render the cubeglBindVertexArray(cubeVAO);glDrawArrays(GL_TRIANGLES, 0, 36);// also draw the lamp objectlightingCubeShader.use();lightingCubeShader.setMat4("projection", projection);lightingCubeShader.setMat4("view", view);model = glm::mat4(1.0f);model = glm::translate(model, lightPos);model = glm::scale(model, glm::vec3(0.2f)); // a smaller cubelightingCubeShader.setMat4("model", model);glBindVertexArray(lightCubeVAO);glDrawArrays(GL_TRIANGLES, 0, 36);// glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)// -------------------------------------------------------------------------------glfwSwapBuffers(window);glfwPollEvents();}glDeleteVertexArrays(1, &cubeVAO);glDeleteVertexArrays(1, &lightCubeVAO);glDeleteBuffers(1, &VBO);glfwTerminate();return 0;}
void processInput(GLFWwindow* window)
{if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)glfwSetWindowShouldClose(window, true);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);
}void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{// make sure the viewport matches the new window dimensions; note that width and // height will be significantly larger than specified on retina displays.glViewport(0, 0, width, height);
}
// glfw: whenever the mouse moves, this callback is called
// -------------------------------------------------------
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 = xpos - lastX;float yoffset = lastY - ypos; // reversed since y-coordinates go from bottom to toplastX = xpos;lastY = ypos;camera.ProcessMouseMovement(xoffset, yoffset);
}// glfw: whenever the mouse scroll wheel scrolls, this callback is called
// ----------------------------------------------------------------------
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
{camera.ProcessMouseScroll(static_cast<float>(yoffset));
}

2. 动态光源位置

目前，我们的光源是静止的，尝试使用sin或cos函数让光源在场景中来回移动。观察光照随时间的改变能让你更容易理解冯氏光照模型。

        //动态修改 光源位置lightPos.x = 1.0f + sin(glfwGetTime()) * 2.0f;lightPos.y = sin(glfwGetTime() / 2.0f) * 1.0f;lightingShader.setVec3("lightPos", lightPos);

基础光照 - LearnOpenGL CN (learnopengl-cn.github.io)