目录

变换是什么？对于OpenGL的摄像机又意味着什么？

MVP变换

投影变换

正交投影变换

透视投影变换 

摄像机/投影矩阵的应用

绘制单个立方体——源码及渲染结果

绘制多个立方体——源码及渲染结果

构建摄像机类——实现控制摄像机移动

摄像机坐标系的构成

摄像机坐标系的参数构建

摄像机关键参数提取（移动参数）

摄像机平移功能实现

构建摄像机类——实现控制摄像机旋转

摄像机front向量的xyz

鼠标跟踪控制方法分解 

摄像机旋转功能实现

变换是什么？对于OpenGL的摄像机又意味着什么？

答：就是将三维物体映射到摄像机屏幕的过程。

 在线性代数中，变换=矩阵，任何3D变化都可以通过矩阵来表示。 

MVP变换

那么问题来了，如何将三维物体映射到屏幕空间呢？

答：经过MVP变换。

这里不对MVP变换做过多的展开，详细理论可参考GAMES101的课程。

那么如何变换呢？如何获得物体在观察坐标系下的位置呢？

不失一般性，我们考虑一个简单的情况，即观察坐标系与世界坐标系平行：

•  首先我们将观察坐标系平移变换到世界坐标系原点，那么会有一个对应的矩阵
• 我们用同样的矩阵，对物体做一次变换，即可得到物体在观察坐标系下的位置

但更一般的情况是：摄像机空间与世界空间存在一定的角度：

那此时如何得到物体在摄像机空间的相对位置呢？

答：可以将摄像机移动到世界坐标系原点，然后将摄像机坐标系的三个正交基旋转至与世界坐标系重合。

但问题来了，如何获得这个旋转矩阵呢？这个矩阵并不好算。

但我们可以曲线救国，利用矩阵的逆。

既然直接求摄像机空间旋转至世界空间不好求，那我们可以把世界空间旋转至摄像机空间，并获得一个矩阵，然后再求这个矩阵的逆，即为摄像机空间旋转至世界空间的变换矩阵。

投影变换

投影分两种：

投影变换的目标是：将空间中的点P变换到摄像机平面坐标系内，并且做成NDC（标准设备坐标）的形式。NDC为了兼容不同窗口的宽高，让x与y的都同一到（-1，1）范围内，之后各自乘以宽高

正交投影变换

透视投影变换 

空间中的点投射到屏幕近剪裁平面的坐标。

过多的数学推导这里不做展示，直接给出结果：

摄像机/投影矩阵的应用

下载并载入glm第三方库：

类似之前实践的思路，我们需要更改和设置：

• 设置glm::mat4 初始化view摄像机矩阵和proj投影矩阵
• 设置好需要绘制的正方体六个面
• 处理相应锚点并激活，这里不需要索引处理了
• 在shader中添加设置矩阵的方法
• 在render()中，利用glm设置相应矩阵，并开启深度测试

绘制单个立方体——源码及渲染结果

#include "Base.h"
#include "Shader.h"
#include "ffImage.h"void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void processInput(GLFWwindow* window);
void initModel();
void initShader(const char* _vertexPath, const char* _fragPath);
void initTexture();
void render();unsigned int VBO = 0;
unsigned int VAO = 0;
unsigned int EBO = 0;
unsigned int _texture = 0;Shader _shader;
ffImage* _pImage = nullptr;glm::mat4 _viewMatrix(1.0f);
glm::mat4 _projMatrix(1.0f);
int _width = 800;
int _height = 600;int main() {//初始化OpenGL上下文环境，OpenGL是一个状态机，会保存当前状态下的渲染状态以及管线的状态glfwInit(); //，3版本以上glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);//用OpenGL核心开发模式glfwWindowHint(GLFW_OPENGL_PROFILE,GLFW_OPENGL_CORE_PROFILE);//创建窗体GLFWwindow* window = glfwCreateWindow(800, 600, "OpenGl Core", nullptr, nullptr);if (window == nullptr) {std::cout << "Failed to create GLFW window" << std::endl;glfwTerminate();return -1;}//把当前上下文绑定至当前窗口glfwMakeContextCurrent(window);//通过glad绑定各种函数指针if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {std::cout << "Failed to initialize GLAD" << std::endl;return -1;}//视口：需要渲染的东西在哪里glViewport(0, 0, _width, _height);//当Frame大小变动，调用回调函数调整视口大小glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);initModel();initShader("vertexShader.glsl", "fragmentShader.glsl");initTexture();//防止窗口结束退出while (!glfwWindowShouldClose(window)) {processInput(window);render();//双缓冲glfwSwapBuffers(window);glfwPollEvents();}//结束，释放资源glfwTerminate();return 0;}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);}
}//渲染
void render() {//擦除画布，用定义的颜色填充glClearColor(0.2f, 0.3f, 0.3f, 1.0f);glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);glEnable(GL_DEPTH_TEST);//眼睛（摄像机）位置，看向位置，摄像机上方位置_viewMatrix = glm::lookAt(glm::vec3(3.0f, 3.0f, 3.0f),glm::vec3(0.0f, 0.0f, 0.0f),glm::vec3(0.0f, 1.0f, 0.0f));//透视投影矩阵：视锥角，宽高比，近平面，远平面_projMatrix = glm::perspective(glm::radians(45.0f),(float)_width / (float)_height,0.1f,100.0f);glBindTexture(GL_TEXTURE_2D, _texture);_shader.start();_shader.setMatrix("_viewMatrix", _viewMatrix);_shader.setMatrix("_projMatrix", _projMatrix);glBindVertexArray(VAO);glDrawArrays(GL_TRIANGLES, 0, 36);_shader.end();
}//构建模型数据：VBO，VAO
void initModel() {//float vertices[] = {//	//顶点信息				颜色信息			纹理信息//	0.5f, 0.5f, 0.0f,		1.0f,0.0f,0.0f,		1.0f,1.0f,//	0.5f, -0.5f, 0.0f,	 	0.0f,1.0f,0.0f,		1.0f,0.0f,//	-0.5f, -0.5f, 0.0f,		0.0f,0.0f,1.0f,		0.0f,0.0f,//	-0.5f, 0.5f, 0.0f,		0.0f,1.0f,0.0f,		0.0f,1.0f//};float vertices[] = {//第一个面，六个顶点两个三角形-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,-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,-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,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,-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,-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};glGenVertexArrays(1, &VAO);glBindVertexArray(VAO);//之后的VBO便属于了VAO的管理范围glGenBuffers(1, &VBO);//绑定哪一种buffer， glBindBuffer(GL_ARRAY_BUFFER, VBO);//分配显存：分配哪种buffer，分配显存大小，分配地址，使用数据的方式glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);//对哪个锚点进行操作：layout=0的锚点，读3个顶点，类型为float，不需要归一化，每次步长为3个float大小，从0处开始读glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(sizeof(float)*3));//打开锚点：激活glEnableVertexAttribArray(0);glEnableVertexAttribArray(1);//解绑glBindBuffer(GL_ARRAY_BUFFER, 0);glBindVertexArray(0);
}//
void initShader(const char* _vertexPath, const char* _fragPath) {_shader.initShader(_vertexPath, _fragPath);
}void initTexture() {_pImage = ffImage::readFromFile("res/wall.jpg");//纹理绑定glGenTextures(1, &_texture);glBindTexture(GL_TEXTURE_2D, _texture);//纹理属性设置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_NEAREST);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);//读入图片数据glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, _pImage->getWidth(), _pImage->getHeight(), 0, GL_RGBA, GL_UNSIGNED_BYTE,_pImage->getData());
}

//vertexShader.glsl
#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec2 aUV;out vec2 outUV;uniform mat4 _modelMatrix;
uniform mat4 _viewMatrix;
uniform mat4 _projMatrix;void main()
{gl_Position = _projMatrix * _viewMatrix * _modelMatrix * vec4(aPos.x, aPos.y, aPos.z, 1.0);outUV = aUV;
};

//fragmentShader.glsl
#version 330 core
out vec4 FragColor;in vec2 outUV;uniform sampler2D outTexture;void main()
{FragColor = texture(outTexture, outUV) ;
};

绘制多个立方体——源码及渲染结果

这里绘制10个立方体，对每一个立方体先进行一个平移操作，并且进行旋转操作

//渲染
void render() {//擦除画布，用定义的颜色填充glClearColor(0.2f, 0.3f, 0.3f, 1.0f);glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);glEnable(GL_DEPTH_TEST);glm::vec3 modelVecs[] = {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)};_viewMatrix = glm::lookAt(glm::vec3(0.0f, 0.0f, 3.0f), glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f, 1.0f, 0.0f));_projMatrix = glm::perspective(glm::radians(45.0f), (float)_width / (float)_height, 0.1f, 100.0f);glBindTexture(GL_TEXTURE_2D, _texture);for (int i = 0; i < 10; i++){glm::mat4 _modelMatrix(1.0f);//单位阵_modelMatrix = glm::translate(_modelMatrix, modelVecs[i]);//平移_modelMatrix = glm::rotate(_modelMatrix, glm::radians((float)glfwGetTime() * (i + 1) * 10), glm::vec3(0.0f, 1.0f, 0.0f));_shader.start();_shader.setMatrix("_modelMatrix", _modelMatrix);_shader.setMatrix("_viewMatrix", _viewMatrix);_shader.setMatrix("_projMatrix", _projMatrix);glBindVertexArray(VAO);glDrawArrays(GL_TRIANGLES, 0, 36);_shader.end();}
}

构建摄像机类——实现控制摄像机移动

需要完成的任务：

• 接受鼠标以及键盘的信息，并做出反馈
• 提供接口，控制摄像机上下左右观望、前后左右移动

摄像机坐标系的构成

• 确定位置：Position
• 确定朝向：与世界坐标系做连线，但相反的方向作为z轴
• 确定右方：人为规定一个up向量，比如世界坐标的y轴，与摄像机空间z轴做叉乘，得到right向量
• 确定上方：通过已求得的两个向量right和direction，叉乘获得up向量

摄像机坐标系的参数构建

摄像机关键参数提取（移动参数）

摄像机平移功能实现

摄像机类：

//Camera.h
#pragma once
#include "Base.h"enum class CAMERA_MOVE{MOVE_LEFT,MOVE_RIGHT,MOVE_FRONT,MOVE_BACK
};class Camera
{
private:glm::vec3	m_position;glm::vec3	m_front;glm::vec3	m_up;float		m_speed;glm::mat4	m_vMatrix;public:Camera() {m_position = glm::vec3(1.0f);m_front= glm::vec3(1.0f);m_up = glm::vec3(1.0f);m_speed = 0.01f;m_vMatrix = glm::mat4(1.0f);}~Camera() {}void lookAt(glm::vec3 _pos, glm::vec3 _front, glm::vec3 _up);void update();glm::mat4 getMatrix() { return m_vMatrix; }void move(CAMERA_MOVE _mode);void setspeed(float _speed);
};

//Camera.cpp
#include "Camera.h"void Camera::lookAt(glm::vec3 _pos, glm::vec3 _front, glm::vec3 _up)
{m_position = _pos;m_front = glm::normalize(_front);m_up = _up;m_vMatrix = glm::lookAt(m_position, m_position + m_front, m_up);
}void Camera::update()
{m_vMatrix = glm::lookAt(m_position, m_position + m_front, m_up);
}void Camera::move(CAMERA_MOVE _mode)
{switch (_mode){case CAMERA_MOVE::MOVE_LEFT:m_position -= glm::normalize(glm::cross(m_front, m_up)) * m_speed;break;case CAMERA_MOVE::MOVE_RIGHT:m_position += glm::normalize(glm::cross(m_front, m_up)) * m_speed;break;case CAMERA_MOVE::MOVE_FRONT:m_position += m_speed * m_front;break;case CAMERA_MOVE::MOVE_BACK:m_position -= m_speed * m_front;break;default:break;}
}void Camera::setspeed(float _speed)
{m_speed = _speed;
}

 main.cpp：

#include "Base.h"
#include "Shader.h"
#include "ffImage.h"
#include "Camera.h"void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void processInput(GLFWwindow* window);
void initModel();
void initShader(const char* _vertexPath, const char* _fragPath);
void initTexture();
void render();unsigned int VBO = 0;
unsigned int VAO = 0;
unsigned int EBO = 0;
unsigned int _texture = 0;Shader _shader;
ffImage* _pImage = nullptr;
Camera	_camera;glm::mat4 _projMatrix(1.0f);
int _width = 800;
int _height = 600;int main() {//初始化OpenGL上下文环境，OpenGL是一个状态机，会保存当前状态下的渲染状态以及管线的状态glfwInit(); //，3版本以上glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);//用OpenGL核心开发模式glfwWindowHint(GLFW_OPENGL_PROFILE,GLFW_OPENGL_CORE_PROFILE);//创建窗体GLFWwindow* window = glfwCreateWindow(800, 600, "OpenGl Core", nullptr, nullptr);if (window == nullptr) {std::cout << "Failed to create GLFW window" << std::endl;glfwTerminate();return -1;}//把当前上下文绑定至当前窗口glfwMakeContextCurrent(window);//通过glad绑定各种函数指针if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {std::cout << "Failed to initialize GLAD" << std::endl;return -1;}//视口：需要渲染的东西在哪里glViewport(0, 0, _width, _height);//当Frame大小变动，调用回调函数调整视口大小glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);_camera.lookAt(glm::vec3(0.0f, 0.0f, 3.0f), glm::vec3(0.0f, 0.0f, -1.0f), glm::vec3(0.0f, 1.0f, 0.0f));_camera.setspeed(0.01f);initModel();initShader("vertexShader.glsl", "fragmentShader.glsl");initTexture();//防止窗口结束退出while (!glfwWindowShouldClose(window)) {processInput(window);render();//双缓冲glfwSwapBuffers(window);glfwPollEvents();}//结束，释放资源glfwTerminate();return 0;}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);}if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS) {_camera.move(CAMERA_MOVE::MOVE_FRONT);}if (glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS) {_camera.move(CAMERA_MOVE::MOVE_BACK);}if (glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS) {_camera.move(CAMERA_MOVE::MOVE_LEFT);}if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS) {_camera.move(CAMERA_MOVE::MOVE_RIGHT);}
}//渲染
void render() {//擦除画布，用定义的颜色填充glClearColor(0.2f, 0.3f, 0.3f, 1.0f);glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);glEnable(GL_DEPTH_TEST);glm::vec3 modelVecs[] = {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)};_camera.update();_projMatrix = glm::perspective(glm::radians(45.0f), (float)_width / (float)_height, 0.1f, 100.0f);glBindTexture(GL_TEXTURE_2D, _texture);for (int i = 0; i < 10; i++){glm::mat4 _modelMatrix(1.0f);//单位阵_modelMatrix = glm::translate(_modelMatrix, modelVecs[i]);//平移_modelMatrix = glm::rotate(_modelMatrix, glm::radians((float)glfwGetTime() * (i + 1) * 10), glm::vec3(0.0f, 1.0f, 0.0f));//绕y轴旋转_shader.start();_shader.setMatrix("_modelMatrix", _modelMatrix);_shader.setMatrix("_viewMatrix", _camera.getMatrix());_shader.setMatrix("_projMatrix", _projMatrix);glBindVertexArray(VAO);glDrawArrays(GL_TRIANGLES, 0, 36);_shader.end();}
}//构建模型数据：VBO，VAO
void initModel() {//float vertices[] = {//	//顶点信息				颜色信息			纹理信息//	0.5f, 0.5f, 0.0f,		1.0f,0.0f,0.0f,		1.0f,1.0f,//	0.5f, -0.5f, 0.0f,	 	0.0f,1.0f,0.0f,		1.0f,0.0f,//	-0.5f, -0.5f, 0.0f,		0.0f,0.0f,1.0f,		0.0f,0.0f,//	-0.5f, 0.5f, 0.0f,		0.0f,1.0f,0.0f,		0.0f,1.0f//};float vertices[] = {//第一个面，六个顶点两个三角形-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,-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,-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,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,-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,-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};glGenVertexArrays(1, &VAO);glBindVertexArray(VAO);//之后的VBO便属于了VAO的管理范围glGenBuffers(1, &VBO);//绑定哪一种buffer， glBindBuffer(GL_ARRAY_BUFFER, VBO);//分配显存：分配哪种buffer，分配显存大小，分配地址，使用数据的方式glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);//对哪个锚点进行操作：layout=0的锚点，读3个顶点，类型为float，不需要归一化，每次步长为3个float大小，从0处开始读glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(sizeof(float)*3));//打开锚点：激活glEnableVertexAttribArray(0);glEnableVertexAttribArray(1);//解绑glBindBuffer(GL_ARRAY_BUFFER, 0);glBindVertexArray(0);
}//
void initShader(const char* _vertexPath, const char* _fragPath) {_shader.initShader(_vertexPath, _fragPath);
}void initTexture() {_pImage = ffImage::readFromFile("res/wall.jpg");//纹理绑定glGenTextures(1, &_texture);glBindTexture(GL_TEXTURE_2D, _texture);//纹理属性设置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_NEAREST);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);//读入图片数据glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, _pImage->getWidth(), _pImage->getHeight(), 0, GL_RGBA, GL_UNSIGNED_BYTE,_pImage->getData());
}

结果：

构建摄像机类——实现控制摄像机旋转

摄像机front向量的xyz

front.y：

front.x 和 front.z：

计算方式：

鼠标跟踪控制方法分解 

摄像机旋转功能实现

• 在主函数中设置鼠标模式，同时绑定回调函数
• 在摄像机类中添加相应属性及方法
• 根据之前的理论，编写代码计算个方向向量，并归一化
• 在鼠标移动时，计算pitch和yaw角度的变化

//Camera.cpp
#include "Camera.h"void Camera::lookAt(glm::vec3 _pos, glm::vec3 _front, glm::vec3 _up)
{m_position = _pos;m_front = glm::normalize(_front);m_up = _up;m_vMatrix = glm::lookAt(m_position, m_position + m_front, m_up);
}void Camera::update()
{m_vMatrix = glm::lookAt(m_position, m_position + m_front, m_up);
}void Camera::move(CAMERA_MOVE _mode)
{switch (_mode){case CAMERA_MOVE::MOVE_LEFT:m_position -= glm::normalize(glm::cross(m_front, m_up)) * m_speed;break;case CAMERA_MOVE::MOVE_RIGHT:m_position += glm::normalize(glm::cross(m_front, m_up)) * m_speed;break;case CAMERA_MOVE::MOVE_FRONT:m_position += m_speed * m_front;break;case CAMERA_MOVE::MOVE_BACK:m_position -= m_speed * m_front;break;default:break;}
}void Camera::setspeed(float _speed)
{m_speed = _speed;
}void Camera::pitch(float _yOffset)
{m_pitch += _yOffset * m_sensitivity;if (m_pitch >= 89.0f) {m_pitch = 89.0f;}if (m_pitch <= -89.0f) {m_pitch = -89.0f;}m_front.y = sin(glm::radians(m_pitch));m_front.x = cos(glm::radians(m_yaw)) * cos(glm::radians(m_pitch));m_front.z = sin(glm::radians(m_yaw)) * cos(glm::radians(m_pitch));m_front = glm::normalize(m_front);update();
}void Camera::yaw(float _xOffset)
{m_yaw += _xOffset * m_sensitivity;m_front.y = sin(glm::radians(m_pitch));m_front.x = cos(glm::radians(m_yaw)) * cos(glm::radians(m_pitch));m_front.z = sin(glm::radians(m_yaw)) * cos(glm::radians(m_pitch));m_front = glm::normalize(m_front);update();
}void Camera::setSensitivity(float _s)
{m_sensitivity = _s;
}void Camera::onMouseMove(double _xpos, double _ypos)
{if (m_firseMove) {m_xpos = m_xpos;m_ypos = m_ypos;m_firseMove = false;return;}float _xOffset = _xpos - m_xpos;float _yOffset = -(_ypos - m_ypos);m_xpos = _xpos;m_ypos = _ypos;pitch(_yOffset);yaw(_xOffset);
}