摄像机

摄像机的引入控制view矩阵。同时可控制透视的fov视角。来模拟人的观察眼睛。 因此可使用摄像机位置控制view， fov控制视角。 使用欧拉角控制鼠标方向位置，因此要计算 yaw， pitch 1. 摄像机方向，view方向

> glm::lookAt( eye, center, up)
```cpp
    view = glm::lookAt(cameraPos, cameraPos + cameraFront, cameraUp);
```

2. 透视矩阵构造 > projection = glm::perspective(glm::radians(fov)/fovy/, aspect, near, far); > fov 弧度 宽高使用显示区域的宽高，近裁剪面和远裁剪面

3. 鼠标位置，鼠标滚轮控制缩放和位置。

   1. glfw 按键检测
      1. 每帧 glfwGetKey获取按键状态处理 cpp void processInput(GLFWwindow *window) { if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS) glfwSetWindowShouldClose(window, true); float cameraSpeed = 2.5f * deltaTime; 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; }
   2. 鼠标位置检测 glfwSetCursorPosCallback(window, mouse_callback); cpp void mouse_callback(GLFWwindow* window, double xpos, double ypos) { if (firstMouse) { lastX = xpos; lastY = ypos; firstMouse = false; } float xoffset = xpos - lastX; float yoffset = lastY - ypos; lastX = xpos; lastY = ypos; float sensitivity = 0.05; xoffset *= sensitivity; yoffset *= sensitivity; yaw += xoffset; pitch += yoffset; if (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); }
   3. 鼠标滚轮检测 glfwSetScrollCallback(window, scroll_callback); cpp void scroll_callback(GLFWwindow* window, double xoffset, double yoffset) { if (fov >= 1.0f && fov <= 45.0f) fov -= yoffset; if (fov <= 1.0f) fov = 1.0f; if (fov >= 45.0f) fov = 45.0f; }
   4. 鼠标焦点不显示光标 cpp glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);

4. 应用于观察view矩阵和透视projection矩阵, 就可以通过鼠标位置和滑轮控制 矩阵，使得图像移动。 cpp view = glm::lookAt(cameraPos, cameraPos + cameraFront, cameraUp); projection = glm::perspective(glm::radians(fov), (float)wWidth / (float)wHeight, 0.1f, 100.0f);

5. 完整代码 cpp #include "glad/glad.h" #include "GLFW/glfw3.h" //图片库 #define STB_IMAGE_IMPLEMENTATION #include "stb_image.h" //glm OpenGL Math库 #include "glm/glm.hpp" #include "glm/gtc/matrix_transform.hpp" #include "glm/gtc/type_ptr.hpp" #include "shader.h" #include <iostream> using namespace std; const int wWidth = 800, wHeight = 600; const char* wName = "LearnOpenGL"; 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); float cameraSpeed = 0.05f; // adjust accordingly 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 float lastX = 400, lastY = 300; float yaw = 0, pitch = 0; bool firstMouse = true; float fov = 45.0f; //立方体顶点 float vertices[] = { //一面 -0.5f, -0.5f, -0.5f, 0.0f, 0.0f, 0.5f, -0.5f, -0.5f, 1.0f, 0.0f, 0.5f, 0.5f, -0.5f, 1.0f, 1.0f, 0.5f, 0.5f, -0.5f, 1.0f, 1.0f, -0.5f, 0.5f, -0.5f, 0.0f, 1.0f, -0.5f, -0.5f, -0.5f, 0.0f, 0.0f, //一面 -0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 0.5f, -0.5f, 0.5f, 1.0f, 0.0f, 0.5f, 0.5f, 0.5f, 1.0f, 1.0f, 0.5f, 0.5f, 0.5f, 1.0f, 1.0f, -0.5f, 0.5f, 0.5f, 0.0f, 1.0f, -0.5f, -0.5f, 0.5f, 0.0f, 0.0f, //一面 -0.5f, 0.5f, 0.5f, 1.0f, 0.0f, -0.5f, 0.5f, -0.5f, 1.0f, 1.0f, -0.5f, -0.5f, -0.5f, 0.0f, 1.0f, -0.5f, -0.5f, -0.5f, 0.0f, 1.0f, -0.5f, -0.5f, 0.5f, 0.0f, 0.0f, -0.5f, 0.5f, 0.5f, 1.0f, 0.0f, //一面 0.5f, 0.5f, 0.5f, 1.0f, 0.0f, 0.5f, 0.5f, -0.5f, 1.0f, 1.0f, 0.5f, -0.5f, -0.5f, 0.0f, 1.0f, 0.5f, -0.5f, -0.5f, 0.0f, 1.0f, 0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 0.5f, 0.5f, 0.5f, 1.0f, 0.0f, //一面 -0.5f, -0.5f, -0.5f, 0.0f, 1.0f, 0.5f, -0.5f, -0.5f, 1.0f, 1.0f, 0.5f, -0.5f, 0.5f, 1.0f, 0.0f, 0.5f, -0.5f, 0.5f, 1.0f, 0.0f, -0.5f, -0.5f, 0.5f, 0.0f, 0.0f, -0.5f, -0.5f, -0.5f, 0.0f, 1.0f, //一面 -0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.5f, 0.5f, -0.5f, 1.0f, 1.0f, 0.5f, 0.5f, 0.5f, 1.0f, 0.0f, 0.5f, 0.5f, 0.5f, 1.0f, 0.0f, -0.5f, 0.5f, 0.5f, 0.0f, 0.0f, -0.5f, 0.5f, -0.5f, 0.0f, 1.0f }; void framebuffer_size_callback(GLFWwindow* window, int width, int height) { glViewport(0, 0, width, height); } void processInput(GLFWwindow *window) { if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS) glfwSetWindowShouldClose(window, true); float cameraSpeed = 2.5f * deltaTime; 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; } void mouse_callback(GLFWwindow* window, double xpos, double ypos) { if (firstMouse) { lastX = xpos; lastY = ypos; firstMouse = false; } float xoffset = xpos - lastX; float yoffset = lastY - ypos; lastX = xpos; lastY = ypos; float sensitivity = 0.05; xoffset *= sensitivity; yoffset *= sensitivity; yaw += xoffset; pitch += yoffset; if (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) { if (fov >= 1.0f && fov <= 45.0f) fov -= yoffset; if (fov <= 1.0f) fov = 1.0f; if (fov >= 45.0f) fov = 45.0f; } int main() { //1. 初始化 if (glfwInit() == GLFW_FALSE) { cout << "init glfw fail"; return 1; } //2. 基本设置 glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3); glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); #if __APPLE__ glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GLFW_TRUE); #endif //3. 创建窗口 GLFWwindow *window = glfwCreateWindow(wWidth, wHeight, wName, nullptr, nullptr); if (window == nullptr) { cout << "Failed to create GLFW window"; goto TERMINATE; //return 1; } //4. 当前主线程上下文窗口 glfwMakeContextCurrent(window); //5. 使用glad管理OpenGL指针。 if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) { std::cout << "Failed to initialize GLAD" << std::endl; goto TERMINATE; //return 1; } //6. 设置视口 glViewport(0, 0, wWidth, wHeight); //7. 设置resize回调，对应刷新视口 glfwSetFramebufferSizeCallback(window, framebuffer_size_callback); glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED); glfwSetCursorPosCallback(window, mouse_callback); glfwSetScrollCallback(window, scroll_callback); Shader shader("res/shaders/sample_vertex_mvp.shader", "res/shaders/sample_fragment_mvp.shader"); unsigned int VBO, VAO/*, EBO*/; glGenVertexArrays(1, &VAO); glBindVertexArray(VAO); glGenBuffers(1, &VBO); glBindBuffer(GL_ARRAY_BUFFER, VBO); glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW); /*glGenBuffers(1, &EBO); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO); glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);*/ //1. 指定顶点的顶点属性的结构，顶点 3个float，从0开始，整体每一组数据8个。 glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0); glEnableVertexAttribArray(0); //2. 指定uv的顶点属性的结构，uv 2个float，从6开始，整体每一组数据8个。 glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float))); glEnableVertexAttribArray(2); glBindBuffer(GL_ARRAY_BUFFER, 0); glBindVertexArray(0); unsigned int texture1, texture2; //加载贴图1 glGenTextures(1, &texture1); glBindTexture(GL_TEXTURE_2D, texture1); // 设置 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 filtering 参数 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); // 加载解析贴图文件 int width, height, nrChannels; stbi_set_flip_vertically_on_load(true); // tell stb_image.h to flip loaded texture's on the y-axis. unsigned char* data = stbi_load("./res/textures/container.jpg", &width, &height, &nrChannels, 0); if (data) { //第一个 GL_RGB 将被转换的格式， 第二个GL_RGB原始文件的格式， 格式不匹配会报错。 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); //加载贴图2 glGenTextures(1, &texture2); glBindTexture(GL_TEXTURE_2D, texture2); // 设置 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 filtering 参数 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); // l加载解析贴图文件 data = stbi_load("./res/textures/awesomeface.png", &width, &height, &nrChannels, 0); if (data) { //第一个 GL_RGB 将被转换的格式， 第二个GL_RGB原始文件的格式， 格式不匹配会报错。 glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 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); //指定采样器贴图储存的位置 shader.use(); shader.setInt("texture1", 0); shader.setInt("texture2", 1); 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) }; lastFrame = glfwGetTime(); while (!glfwWindowShouldClose(window)) { float currentFrame = glfwGetTime(); deltaTime = currentFrame - lastFrame; lastFrame = currentFrame; processInput(window); glClearColor(0.2f, 0.3f, 0.3f, 1.0f); glClear(GL_COLOR_BUFFER_BIT| GL_DEPTH_BUFFER_BIT); // bind Texture1 glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, texture1); // bind Texture2 glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, texture2); shader.use(); glm::mat4 view = glm::mat4(1.0f); glm::mat4 projection = glm::mat4(1.0f); //view = glm::translate(view, glm::vec3(0.0f, 0.0f, -3.0f)); view = glm::lookAt(cameraPos, cameraPos + cameraFront, cameraUp); projection = glm::perspective(glm::radians(fov), (float)wWidth / (float)wHeight, 0.1f, 100.0f); shader.setMat4("projection", projection); shader.setMat4("view", view); glBindVertexArray(VAO); glEnable(GL_DEPTH_TEST); for (size_t i = 0; i < 10; i++) { glm::mat4 model(1.0f); model = glm::translate(model, cubePositions[i]); model = glm::rotate(model, (float)glfwGetTime() * glm::radians(50.0f), glm::vec3(0.5f, 1.0f, 0.0f)); float angle = 20.0f * i; model = glm::rotate(model, glm::radians(angle), glm::vec3(1.0f, 0.3f, 0.5f)); shader.setMat4("model", model); glDrawArrays(GL_TRIANGLES, 0, 36); } glfwSwapBuffers(window); glfwPollEvents(); } glDeleteVertexArrays(1, &VAO); glDeleteBuffers(1, &VBO); //glDeleteBuffers(1, &EBO); TERMINATE: glfwTerminate(); return 0; }