LearnOpenGL---绘制三角形

绘制三角形

#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <iostream>const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;/// <summary>
/// 当用户改变窗口大小时，视口也应该被调整，因此编写回调函数，每次改变窗口大小的时候被调用
/// </summary>
/// <param name="window"></param>
/// <param name="width"></param>
/// <param name="height"></param>
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{//再开始渲染之前需要告诉OpenGL渲染窗口的尺寸大小，即视口，这样OpenGL才能知道怎样根据窗口大小显示数据和坐标//通过glViewport设置视口的尺寸：前两个参数控制窗口左下角的位置，后两个参数控制宽度和高度glViewport(0, 0, width, height);
}void processInput(GLFWwindow* window)
{//判断是否按下esc键，如果按下，那么关闭glfwif (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)glfwSetWindowShouldClose(window, true);
}//创建顶点着色器
const char* vertexShaderSource = "#version 330 core\n"
"layout(location = 0) in vec3 aPos;\n"
"void main()\n"
"{\n"
"gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0f);\n"
"}\n";//创建片段着色器
const char* fragmentShaderSource = "#version 330 core\n"
"out vec4 FragColor;\n"
"void main()\n"
"{\n"
"FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);\n"
"}\n";int main()
{//实例化GLFW窗口glfwInit();//将主版本号GLFW_CONTEXT_VERSION_MAJOR和次版本号GLFW_CONTEXT_VERSION_MINOR设置为3.3glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);//使用的是核心模式glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);//创建一个窗口对象GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "Triangle", NULL, NULL);if (window == NULL){std::cout << "创建GLFW窗口失败" << std::endl;glfwTerminate();return -1;}glfwMakeContextCurrent(window);//GLAD是用来管理OpenGL的指针的，所以在调用任何OpenGL的函数之前我们需要初始化GLAD//我们给GLAD传入了用来加载系统相关的OpenGL函数指针地址的函数。GLFW给我们的是glfwGetProcAddress，它根据我们编译的系统定义了正确的函数。if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)){std::cout << "实例化GLAD失败" << std::endl;return -1;}//注册回调函数glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);//顶点坐标float vertices[] = {-0.5f, -0.5f, 0.0f,0.5f, -0.5f, 0.0f,-0.5f, 0.5f, 0.0f,0.5f, 0.5f, 0.0f};unsigned int indices[] = {0, 1, 3,0, 2, 3};//顶点缓冲对象unsigned int VBO;glGenBuffers(1, &VBO);//顶点数组对象VAOunsigned int VAO;glGenVertexArrays(1, &VAO);glBindVertexArray(VAO);//元素缓冲对象unsigned int EBO;glGenBuffers(1, &EBO);把顶点数组复制到缓冲中供OpenGL使用glBindBuffer(GL_ARRAY_BUFFER, VBO);//glBufferData是一个专门用来把用户定义的数据复制到当前绑定缓冲的函数。glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);//复制我们的索引数组到一个索引缓冲中，供OpenGL使用glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);//告诉OpenGL如何解析顶点数据（设置顶点属性指针）glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);glEnableVertexAttribArray(0);//创建着色器对象unsigned int vertexShader;vertexShader = glCreateShader(GL_VERTEX_SHADER);glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);glCompileShader(vertexShader);//检查顶点着色器是否编译成功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;}//创建片段着色器unsigned int fragmentShader;fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);glCompileShader(fragmentShader);//创建一个程序对象并且链接unsigned int shaderProgram;shaderProgram = glCreateProgram();glAttachShader(shaderProgram, vertexShader);glAttachShader(shaderProgram, fragmentShader);glLinkProgram(shaderProgram);//检查链接是否成功glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);if (!success) {glGetProgramInfoLog(shaderProgram, 512, NULL, infoLog);std::cout << "链接失败:\n" << infoLog << std::endl;}//删除两个着色器glDeleteShader(vertexShader);glDeleteShader(fragmentShader);//循环渲染//glfwWindowShouldClose函数在我们每次循环的开始前检查一次GLFW是否被要求退出，//如果是的话，该函数返回true，渲染循环将停止运行，之后我们就可以关闭应用程序。while (!glfwWindowShouldClose(window)){//输入processInput(window);//渲染指令glClearColor(0.2f, 0.3f, 0.3f, 1.0f);glClear(GL_COLOR_BUFFER_BIT);glUseProgram(shaderProgram);glBindVertexArray(VAO);//glDrawArrays(GL_TRIANGLES, 0, 3);//从索引缓冲区渲染三角形glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);//检查并调用时间，交换缓冲//glfwPollEvents函数检查有没有触发什么事件（比如键盘输入、鼠标移动等）、更新窗口状态，并调用对应的回调函数（可以通过回调方法手动设置）。glfwSwapBuffers(window);//科普：双缓冲//glfwSwapBuffers函数会交换颜色缓冲（它是一个储存着GLFW窗口每一个像素颜色值的大缓冲），它在这一迭代中被用来绘制，并且将会作为输出显示在屏幕上。glfwPollEvents();}//正确释放/删除之前分配的所有资源glfwTerminate();return 0;
}