畫一個正方形

其實，畫正方形就是畫兩個三角形，用四個頂點以及使用索引來實現
完整代碼在Square項目的Application.cpp里
先貼上窗口初始化代碼

void BaseInit() {glfwInit();//初始化glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);//配置GLFWglfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);//配置GLFWglfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);//glfwWindowHint(GLFW_RESIZABLE, GL_TRUE);float screenWidth = 800.0f;float screenHeight = 600.0f;//創建窗口glWindow = glfwCreateWindow(screenWidth, screenHeight, "LearnOpenGL", nullptr, nullptr);if (glWindow == nullptr){cout << "Failed to create GLFW window" << endl;glfwTerminate();return;}glfwMakeContextCurrent(glWindow);if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)){std::cout << "Failed to initialize GLAD" << std::endl;return;}

畫一個普通的正方形

void NormalSquare() {float vertices[] = {// ---- 位置 ----0.5f, 0.5f, 0.0f, // 右上0.5f, -0.5f, 0.0f, // 右下-0.5f, -0.5f, 0.0f, // 左下-0.5f, 0.5f, 0.0f, // 左上};//索引unsigned int indices[] = {0,1,3,1,2,3};//編譯著色器Shader ourShader("vertex_1.vs", "fragment_1.fs");ourShader.use();//glUseProgram(shaderProgram);unsigned int VAO;//頂點數組glGenVertexArrays(1, &VAO);glBindVertexArray(VAO);//綁定頂點數組緩存unsigned int VBO;glGenBuffers(1, &VBO);glBindBuffer(GL_ARRAY_BUFFER, VBO);glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);//綁定索引緩存unsigned int EBO;glGenBuffers(1, &EBO);glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);// 位置屬性glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);glEnableVertexAttribArray(0);while (!glfwWindowShouldClose(glWindow)){glClearColor(0.2f, 0.3f, 0.3f, 1.0f);glClear(GL_COLOR_BUFFER_BIT);//drawglBindVertexArray(VAO);glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);glBindVertexArray(0);glfwPollEvents();glfwSwapBuffers(glWindow);}glDeleteVertexArrays(1, &VAO);glDeleteBuffers(1, &VBO);glDeleteBuffers(1, &EBO);glfwTerminate(); }

最終效果

畫一個彩色的正方形

和上一個筆記里畫彩色三角形的邏輯一樣，在頂點屬性后面加上顏色屬性，設置數據訪問指針的屬性，記得頂點著色器要加上顏色的輸入(步長和相位)

//彩色正方形 void ColourfulSquare() {float vertices[] = {// ---- 位置 ---- ---- 顏色 ---- 0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, // 右上0.5f, -0.5f, 0.0f, 0.0f, 1.0f, 0.0f, // 右下-0.5f, -0.5f, 0.0f, 0.0f, 0.0f, 1.0f, // 左下-0.5f, 0.5f, 0.0f, 1.0f, 1.0f, 0.0f, // 左上};//索引unsigned int indices[] = {0,1,3,1,2,3};//編譯著色器Shader ourShader("vertex_4.vs", "fragment_4.fs");ourShader.use();//glUseProgram(shaderProgram);unsigned int VAO;//頂點數組glGenVertexArrays(1, &VAO);glBindVertexArray(VAO);//綁定頂點數組緩存unsigned int VBO;glGenBuffers(1, &VBO);glBindBuffer(GL_ARRAY_BUFFER, VBO);glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);//綁定索引緩存unsigned int EBO;glGenBuffers(1, &EBO);glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);// 位置屬性glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);glEnableVertexAttribArray(0);// 顏色屬性glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float))); //最后一個參數是數據的起點glEnableVertexAttribArray(1);while (!glfwWindowShouldClose(glWindow)){glClearColor(0.2f, 0.3f, 0.3f, 1.0f);glClear(GL_COLOR_BUFFER_BIT);//drawglBindVertexArray(VAO);glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);glBindVertexArray(0);glfwPollEvents();glfwSwapBuffers(glWindow);}glDeleteVertexArrays(1, &VAO);glDeleteBuffers(1, &VBO);glDeleteBuffers(1, &EBO);glfwTerminate(); }

最終效果

可以試試線框模式，在while之前加上
glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
效果圖

轉載于:https://www.cnblogs.com/NightFrost/p/10792605.html

總結

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