OpenGL视角和移动速度随鼠标和滚轮变化

难点理解：

主程序：

#define STB_IMAGE_IMPLEMENTATION
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <STB_IMAGE/stb_image.h>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include <Shader/shader_s.h>
#include <iostream>
void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void mouse_callback(GLFWwindow* window, double xpos, double ypos);
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
void processInput(GLFWwindow *window);
// settings
const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;
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);
unsigned int i = 0;
float mixValue = 0.2f;
float deltaTime = 0.0f;	
float lastFrame = 0.0f;
//鼠标的初始位置
float lastX = 400, lastY = 300;
float 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 so we initially rotate a bit to the left.
float pitch = 0.0f;
bool firstMouse = true;
float fov = 45.0f;
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); // uncomment this statement to fix compilation on OS X
#endif
GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);
if (window == NULL)
{
	std::cout &lt;&lt; "Failed to create GLFW window" &lt;&lt; std::endl;
	glfwTerminate();
	return -1;
}
glfwMakeContextCurrent(window);
glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);

// glad: load all OpenGL function pointers
if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
{
	std::cout &lt;&lt; "Failed to initialize GLAD" &lt;&lt; std::endl;
	return -1;
}

//开启Z缓冲，即是深度测试
glEnable(GL_DEPTH_TEST);
// build and compile our shader zprogram
Shader ourShader("6.1.texture.vs", "6.1.texture.fs");


float vertices[] = {
	-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
};

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)
};

unsigned int VBO, VAO;
glGenVertexArrays(1, &amp;VAO);
glGenBuffers(1, &amp;VBO);
//glGenBuffers(1, &amp;EBO);

glBindVertexArray(VAO);

glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

//glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
//glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);

// position attribute
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);

// texture coord attribute
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(1);


//生成纹理
unsigned int texture1, texture2;
glGenTextures(1, &amp;texture1);
glBindTexture(GL_TEXTURE_2D, texture1);

// 为当前绑定的纹理对象设置环绕、过滤方式
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_MIRRORED_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_MIRRORED_REPEAT);
// set texture filtering parameters
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

// load image, create texture and generate mipmaps
int width, height, nrChannels;
//OpenGL要求y轴0.0坐标是在图片的底部的，但是图片的y轴0.0坐标通常在顶部，故需要倒置
//将图片载入生成一个纹理
unsigned char *data1 = stbi_load("F:/C++项目/LibsInclude/src/container.jpg", &amp;width, &amp;height, &amp;nrChannels, 0);
if (data1)
{
//生成纹理
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data1);
//当前绑定的纹理自动生成所有需要的多级渐远纹理
glGenerateMipmap(GL_TEXTURE_2D);
}
else
{
std::cout &lt;&lt; "Failed to load texture" &lt;&lt; std::endl;
}
//释放图像内存
stbi_image_free(data1);


//生成第二个纹理
glGenTextures(1, &amp;texture2);
glBindTexture(GL_TEXTURE_2D, texture2);


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);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
data1 = stbi_load("F:/C++项目/LibsInclude/src/face1.jpeg", &amp;width, &amp;height, &amp;nrChannels, 0);
if (data1)
{
//生成纹理
//笑脸图片有a通道glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);//参数设置为GL_RGBA
//第一个参数指定了纹理目标(Target)。设置为GL_TEXTURE_2D意味着会生成与当前绑定的纹理对象在同一个目标上的纹理（任何绑定到GL_TEXTURE_1D和GL_TEXTURE_3D的纹理不会受到影响）。
//第二个参数为纹理指定多级渐远纹理的级别，如果你希望单独手动设置每个多级渐远纹理的级别的话。这里我们填0，也就是基本级别。
//第三个参数告诉OpenGL我们希望把纹理储存为何种格式。我们的图像只有RGB值，因此我们也把纹理储存为RGB值。
//第四个和第五个参数设置最终的纹理的宽度和高度。我们之前加载图像的时候储存了它们，所以我们使用对应的变量。
//下个参数应该总是被设为0（历史遗留的问题）。
//第七第八个参数定义了源图的格式和数据类型。我们使用RGB值加载这个图像，并把它们储存为char(byte)数组，我们将会传入对应值。
//最后一个参数是真正的图像数据。
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data1);
//当前绑定的纹理自动生成所有需要的多级渐远纹理
glGenerateMipmap(GL_TEXTURE_2D);
}
else
{
std::cout &lt;&lt; "Failed to load texture" &lt;&lt; std::endl;
}
//释放图像内存
stbi_image_free(data1);


//将着色器采样器与纹理单元进行联系在一起
//设置每个采样器的方式告诉OpenGL每个着色器采样器属于哪个纹理单元
//在设置uniform1前先激活着色器
ourShader.use();

//设置uniform值
//texture1着色器采样器接受第一个纹理单元（三种表达方式）
//glUniform1i(glGetUniformLocation(ourShader.ID, "texture1"), 0);
//或者
//ourShader.setInt("texture1", 0);
glUniform1i(glGetUniformLocation(ourShader.ID, "texture1"), GL_TEXTURE0 - GL_TEXTURE0);
//texture2着色器采样器接受第二个纹理单元（三种表达方式）
glUniform1i(glGetUniformLocation(ourShader.ID, "texture2"), GL_TEXTURE1 - GL_TEXTURE0);





// 渲染
while (!glfwWindowShouldClose(window))
{
	//注册回调函数
	glfwSetCursorPosCallback(window, mouse_callback);
	glfwSetScrollCallback(window, scroll_callback);
	float currentFrame = glfwGetTime();
	deltaTime = currentFrame - lastFrame;
	lastFrame = currentFrame;
	processInput(window);

	glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
	//每次渲染迭代之前清除深度缓冲，不然会保留上一帧的深度信息
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	i = i + 1;
	//std::cout &lt;&lt; " i= " &lt;&lt; i&lt;&lt; std::endl;

	//在纹理单元的状态下，将采样器绑定
	// bind Texture：会自动把纹理赋值给片段着色器的采样器
	//先激活纹理单元，然后再绑定，若只有一个纹理单元，默认激活状态
	//GL_TEXTURE0:就是一个纹理单元，是按顺序定义的，OpenGL至少保证有16个纹理单元
	//texture1：代表着色器采样器
	glActiveTexture(GL_TEXTURE0);
	//会绑定这个纹理到当前激活的纹理单元，于是就将纹理和纹理单元联系在一起了
	glBindTexture(GL_TEXTURE_2D, texture1);
	glActiveTexture(GL_TEXTURE1);
	glBindTexture(GL_TEXTURE_2D, texture2);


	// activate shader
	ourShader.use();

	//设置两个纹理的混合度
	ourShader.setFloat("mixValue", mixValue);
	//变换
	//定义变换矩阵
	//模型矩阵（Model):位移（translate)  缩放（scale) 旋转（rotate)
	//glm::mat4 model(1.0f);
	//model = glm::rotate(model, (float)glfwGetTime(), glm::vec3(0.5f, 1.0f, 0.0f));
	//观察矩阵（view)：绕圆轨迹运行
	float radius = 10.0f;
	float camX = sin(glfwGetTime()) * radius;
	float camZ = cos(glfwGetTime()) * radius;
	glm::mat4 view(1.0f);
	// 注意，我们将矩阵向我们要进行移动场景的反方向移动。
	//todo ??? 为社么是cameraPos + cameraFront
	//cameraFront是方向向量的反方向
	view = glm::lookAt(cameraPos, cameraPos + cameraFront, cameraUp);

	//投影矩阵（Projection)
	glm::mat4 projection(1.0f);
	projection = glm::perspective(glm::radians(fov), 800.0f / 600.0f, 0.1f, 100.0f);


	//将矩阵传入着色器
	glUniformMatrix4fv(glGetUniformLocation(ourShader.ID, "view"), 1, GL_FALSE, glm::value_ptr(view));
	glUniformMatrix4fv(glGetUniformLocation(ourShader.ID, "projection"), 1, GL_FALSE, glm::value_ptr(projection));


	glBindVertexArray(VAO);
	for (unsigned int i = 0; i &lt; 10; i++)
	{
		glm::mat4 model(1.0f);
		model = glm::translate(model, cubePositions[i]);
		float angle = 20.0f * (i+1);
		model = glm::rotate(model,  float(glfwGetTime()) * glm::radians(angle), glm::vec3(1.0f, 0.3f, 0.5f));
		glUniformMatrix4fv(glGetUniformLocation(ourShader.ID, "model"), 1, GL_FALSE, glm::value_ptr(model));

		glDrawArrays(GL_TRIANGLES, 0, 36);
	}

	glfwSwapBuffers(window);
	glfwPollEvents();
}
	glDeleteVertexArrays(1, &amp;VAO);
	glDeleteBuffers(1, &amp;VBO);
	//glDeleteBuffers(1, &amp;EBO);
	glfwTerminate();
	return 0;

}
void processInput(GLFWwindow *window)
{
if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
glfwSetWindowShouldClose(window, true);
if (glfwGetKey(window, GLFW_KEY_UP) == GLFW_PRESS)
{
	mixValue += 0.001f;
	if (mixValue &gt;= 1.0f)
	mixValue = 1.0f;
}
if (glfwGetKey(window, GLFW_KEY_DOWN) == GLFW_PRESS)
{
	mixValue -= 0.001f; 
	if (mixValue &lt;= 0.0f)
	mixValue = 0.0f;
}

//更改相机的位置
float cameraSpeed = 2.5 * deltaTime; ; // adjust accordingly
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::cross(cameraFront, cameraUp) * cameraSpeed;
if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS)
	cameraPos += glm::normalize(glm::cross(cameraFront, cameraUp)) * cameraSpeed;

}
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
glViewport(0, 0, width, height);
}
//鼠标事件的回调函数
void mouse_callback(GLFWwindow* window, double xpos, double ypos)
{
//判断鼠标是不是第一次获取输入
if (firstMouse)
{
lastX = xpos;
lastY = ypos;
firstMouse = false;
}
//在窗口坐标中，y轴是从上往下增加的，
float xoffset = xpos  - lastX;
float yoffset = lastY - ypos ;
lastX = xpos;
lastY = ypos;
std::cout &lt;&lt; "ypos=" &lt;&lt; ypos &lt;&lt; std::endl;

//设置零敏度
float sensitivity = 0.05f;
xoffset *= sensitivity;
yoffset *= sensitivity;

yaw  += xoffset;
pitch += yoffset;
//设置限制
if (pitch &gt; 89.0f)
	pitch = 89.0f;
if (pitch &lt;  -89.0f)
	pitch = -89.0f;

//计算方向向量
glm::vec3 front(1.0f);
front.x = cos(glm::radians(pitch)) * cos(glm::radians(yaw));
front.y = sin(glm::radians(pitch));
front.z = cos(glm::radians(pitch)) * sin(glm::radians(yaw));
cameraFront = glm::normalize(front);

}
//鼠标滚轮改变视角大小
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;
}

顶点着色器：

#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec2 aTexCoord;
out vec2 TexCoord;
uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;
void main()
{
gl_Position = projection * view * model * vec4(aPos, 1.0);
TexCoord = vec2(aTexCoord.x, aTexCoord.y);
}

片段着色器：

#version 330 core
out vec4 FragColor;
in vec2 TexCoord;
uniform float mixValue;
// 采样器：解决了如何将纹理对象传给片段着色器
//纹理单元·
uniform sampler2D texture1;
uniform sampler2D texture2;
//这个片段着色器的输出就是纹理的（插值）纹理坐标上的(过滤后的)颜色。
void main()
{
FragColor = mix(texture(texture1, TexCoord), texture(texture2, vec2(TexCoord.x, TexCoord.y)), mixValue);
}

结果：

本文由【黑白双键】发布于开源中国，原文链接：https://my.oschina.net/1024and1314/blog/3136814

OpenGL视角和移动速度随鼠标和滚轮变化

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