概要

主要介绍使用OpenGL绘制一个立方体，并给立方体的六个面赋予不同的颜色，并使立方体可以自动旋转，也可以通过键盘按键A、D、W、S进行左、右、上、下移动。

1.使用GLM函数库(OpenGL Mathematics)进行立方体举矩阵的变换运算；

2.使用PVM矩阵进行坐标系变换。PVM矩阵即 P:projection;V:view;M:model。model矩阵对应从局部坐标系到世界坐标系的变换；view矩阵对应从世界坐标系到观察坐标系的变换；projection 矩阵对应从观察坐标系到剪裁空间的变换。

3.通过注册鼠标和键盘控制函数，使立方体可以通过设备控制。

效果

主要实现代码

main.cpp

#include "glad.c"

#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <stb_image.h>

#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>

#include <learnopengl/shader_m.h>
#include <learnopengl/camera.h>
#include <learnopengl/model.h>

#include <iostream>
#include <GL/gl.h>
#include <GL/glu.h>

//鼠标键盘响应函数
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);


const char *vertexShaderSource = "#version 330 core\n"
	"layout (location = 0) in vec3 aPos;\n"
	"layout (location = 1) in vec3 PosColor;\n"
	"out vec3 positionColor;\n"
	"uniform mat4 model;\n"
	"uniform mat4 view;\n"
	"uniform mat4 projection;\n"
	"void main()\n"
	"{\n"
	"   gl_Position = projection * view * model * vec4(aPos, 1.0);\n"
	"	positionColor=PosColor;\n"
	"}\0";

const char *fragmentShaderSource = "#version 330 core\n"
	"out vec4 FragColor;\n"
	"in vec3 positionColor;\n"
	"void main()\n"
	"{\n"
	"   FragColor = vec4(positionColor,1.0);\n"
	"}\n\0";


const float vertices[] = {                  //立方体数组
	-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,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,  0.5f,0.0f,0.0f,
	0.5f,  0.5f, -0.5f,  0.5f,0.0f,0.0f,
	0.5f, -0.5f, -0.5f,  0.5f,0.0f,0.0f,
	0.5f, -0.5f, -0.5f,  0.5f,0.0f,0.0f,
	0.5f, -0.5f,  0.5f,  0.5f,0.0f,0.0f,
	0.5f,  0.5f,  0.5f,  0.5f,0.0f,0.0f,

	-0.5f, -0.5f, -0.5f,  0.0f,0.5f,0.0f,
	0.5f, -0.5f, -0.5f,  0.0f,0.5f,0.0f,
	0.5f, -0.5f,  0.5f,  0.0f,0.5f,0.0f,
	0.5f, -0.5f,  0.5f,  0.0f,0.5f,0.0f,
	-0.5f, -0.5f,  0.5f,  0.0f,0.5f,0.0f,
	-0.5f, -0.5f, -0.5f,  0.0f,0.5f,0.0f,

	-0.5f,  0.5f, -0.5f,  0.0f,0.0f,0.5f,
	0.5f,  0.5f, -0.5f,  0.0f,0.0f,0.5f,
	0.5f,  0.5f,  0.5f,  0.0f,0.0f,0.5f,
	0.5f,  0.5f,  0.5f,  0.0f,0.0f,0.5f,
	-0.5f,  0.5f,  0.5f,  0.0f,0.0f,0.5f,
	-0.5f,  0.5f, -0.5f,  0.0f,0.0f,0.5f
};

float screen_width = 1920.0f;          //窗口宽度
float screen_height = 1080.0f;          //窗口高度
//相机参数
glm::vec3 camera_position = glm::vec3(0.0f, 0.0f, 3.0f);     //摄像机位置
glm::vec3 camera_front = glm::vec3(0.0f, 0.0f, -1.0f);       //摄像机方向
glm::vec3 camera_up = glm::vec3(0.0f, 1.0f, 0.0f);           //摄像机上向量
//视野
float fov = 45.0f;


Camera camera(glm::vec3(0.0f, 0.0f, 3.0f));
float lastX = screen_width / 2.0f;
float lastY = screen_height / 2.0f;
bool firstMouse = true;

float deltaTime = 0.0f;
float lastFrame = 0.0f;

int main() {
	// 初始化GLFW
	glfwInit();                                                     // 初始化GLFW
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);                  // OpenGL版本为3.3，主次版本号均设为3
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);  // 使用核心模式(无需向后兼容性)
	glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);            // 如果使用的是Mac OS X系统，需加上这行
	glfwWindowHint(GLFW_RESIZABLE, FALSE);						    // 不可改变窗口大小

	// 创建窗口(宽、高、窗口名称)
	auto window = glfwCreateWindow(screen_width, screen_height, "Cube", nullptr, nullptr);
	if (window == nullptr) {                                        // 如果窗口创建失败，输出Failed to Create OpenGL Context
		std::cout << "Failed to Create OpenGL Context" << std::endl;
		glfwTerminate();
		return -1;
	}
	glfwMakeContextCurrent(window);                                 // 将窗口的上下文设置为当前线程的主上下文

	glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
	glfwSetCursorPosCallback(window, mouse_callback);
	glfwSetScrollCallback(window, scroll_callback);
	glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);


	// 初始化GLAD，加载OpenGL函数指针地址的函数
	if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
	{
		std::cout << "Failed to initialize GLAD" << std::endl;
		return -1;
	}

	// 指定当前视口尺寸(前两个参数为左下角位置，后两个参数是渲染窗口宽、高)
	glViewport(0, 0, screen_width, screen_height);

	//////////////////////////////////////////////////////////////////////////
	// build and compile our shader program
	// ------------------------------------
	// vertex shader
	unsigned int vertexShader = glCreateShader(GL_VERTEX_SHADER);
	glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
	glCompileShader(vertexShader);
	// check for shader compile errors
	int success;
	char infoLog[512];
	glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
	if (!success)
	{
		glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
		std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
	}
	// fragment shader
	unsigned int fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
	glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
	glCompileShader(fragmentShader);
	// check for shader compile errors
	glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);
	if (!success)
	{
		glGetShaderInfoLog(fragmentShader, 512, NULL, infoLog);
		std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << infoLog << std::endl;
	}
	// link shaders
	unsigned int shaderProgram = glCreateProgram();
	glAttachShader(shaderProgram, vertexShader);
	glAttachShader(shaderProgram, fragmentShader);
	glLinkProgram(shaderProgram);
	// check for linking errors
	glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);
	if (!success) {
		glGetProgramInfoLog(shaderProgram, 512, NULL, infoLog);
		std::cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infoLog << std::endl;
	}
	glDeleteShader(vertexShader);
	glDeleteShader(fragmentShader);

	//////////////////////////////////////////////////////////////////////////


	//Shader shader("../debug/shader/task-cube.vs", "../debug/shader/task-cube.fs");//加载着色器

	// 生成并绑定VAO和VBO
	GLuint vertex_array_object; // == VAO
	glGenVertexArrays(1, &vertex_array_object);
	glBindVertexArray(vertex_array_object);

	GLuint vertex_buffer_object; // == VBO
	glGenBuffers(1, &vertex_buffer_object);
	glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer_object);
	// 将顶点数据绑定至当前默认的缓冲中
	glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

	// 设置顶点属性指针
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
	glEnableVertexAttribArray(0);

	glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float)));
	glEnableVertexAttribArray(1);


	glEnable(GL_DEPTH_TEST);
	// Render loop主循环
	while (!glfwWindowShouldClose(window)) { 
		//计算每帧的时间差
		float currentFrame = glfwGetTime();
		deltaTime = currentFrame - lastFrame;
		lastFrame = currentFrame;
		processInput(window);

		//进入主循环，清理颜色缓冲深度缓冲
		glClearColor(0.0f, 0.34f, 0.57f, 1.0f);
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);//清理颜色缓冲和深度缓冲

		//shader.use();
		glUseProgram(shaderProgram);

		// Transform坐标变换矩阵
		glm::mat4 model(1);//model矩阵，局部坐标变换至世界坐标
		model = glm::translate(model, glm::vec3(0.0,0.0,0.0));
		model = glm::rotate(model, (float)glfwGetTime(), glm::vec3(0.5f, 1.0f, 0.0f));
		model = glm::scale(model, glm::vec3(1.0f,1.0f,1.0f));
		glm::mat4 view(1);//view矩阵，世界坐标变换至观察坐标系
		view = camera.GetViewMatrix();
		glm::mat4 projection(1);//projection矩阵，投影矩阵
		projection = glm::perspective(glm::radians(camera.Zoom), screen_width / screen_height, 0.1f, 100.0f);

		// 向着色器中传入参数
		std::string strModel = "model";
		std::string strView = "view";
		std::string strProjection = "projection";

	    glUniformMatrix4fv(glGetUniformLocation(shaderProgram, strModel.c_str()), 1, GL_FALSE, &model[0][0]);
		glUniformMatrix4fv(glGetUniformLocation(shaderProgram, strView.c_str()), 1, GL_FALSE, &view[0][0]);
		glUniformMatrix4fv(glGetUniformLocation(shaderProgram, strProjection.c_str()), 1, GL_FALSE, &projection[0][0]);


		//绘制
		glBindVertexArray(vertex_array_object);
		glDrawArrays(GL_TRIANGLES, 0, 36);
		glBindVertexArray(0);


		glfwSwapBuffers(window);
		glfwPollEvents();
	}
	//释放VAOVBO
	glDeleteVertexArrays(1, &vertex_array_object);
	glDeleteBuffers(1, &vertex_buffer_object);

	// 清理所有的资源并正确退出程序
	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)
{
	glViewport(0, 0, width, height);
}

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;

	camera.ProcessMouseMovement(xoffset, yoffset);
}

void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
{
	camera.ProcessMouseScroll(yoffset);
}

完整的项目代码

链接：https://pan.baidu.com/s/1GH_3Yqe4FJt6ivZ1DZkhSA

提取码：u8gs

参考资料

https://www.icourse163.org/learn/HUST-1003636001?tid=1457257442#/learn/content?type=detail&id=1232561377&sm=1