OpenGL是什么？Win10+VS2019下搭建glfw+glad開發環境

1、什么是OpenGL

什么是OpenGL

OpenGL 是一套API接口。

學習這套接口，就可以在那些支持OpenGL的機器上正常使用這些接口，在屏幕上看到繪制的結果。

顯卡廠商的支持

這套接口是 Khronos(科納斯) 這個組織在維護，怎么維護呢? 就是寫一個說明書，指導各個GPU廠家，如果他們要支持OpenGL的話，要怎么實現一個具體的OpenGL庫。Khronos說要實現glDrawArray這個接口，那么廠家就得在他的庫里實現這個接口。如果不實現，那么就不算支持OpenGL。也有一些接口不一定要實現。

Khronos每隔一段時間發布一個新的OpenGL API版本，就是發布這個說明書。一般兩個，一個是core profile，一定要實現的，還有另一個是為了兼容舊版本接口的說明書。

廠家實現的OpenGL庫的內容其實就是廠家自己的團隊整合自己的圖形知識以及GPU硬件的指令。

OpenGL的Open指的是接口是開放的，而具體實現的庫一般都是不公開的。目前據我所知，mesa 3d是一個開源的實現。

與Direct3D的關系

像AMD、Nvidia等圖形硬件廠家還得支持Direct3D，所以他們還得按照微軟的接口說明書，整合Direct3D的庫給Windows使用。

在Windows上，還有一種情況，就是這個OpenGL庫可能是Direct3D接口的一個封裝(Wrapper)。表面上調用OpenGL接口，實際上里面的實現是間接調用了Direct3D接口。

另外OpenGL 只是關注于怎么調用接口實現繪畫 。

為了使用OpenGL，還得初始化一個OpenGL環境。這個環境需要AGL、WGL、GLX這些庫里的接口來建立。這幾個庫分別對應蘋果系統、Windows、還有Linux的X-Window，沒有實現跨平臺。

這也是為什么存在glut（已經不更新了，代替者freeglut，不支持macOS）、glfw這些 “半”跨平臺的框架幫助你輕松地在各平臺下使用OpenGL。

與OpenCV的關系

OpenCV是Intel開源計算機視覺庫。

Opencv是從圖像到數據

OpenGL是從數據到圖像

OpenGL主要功能是什么

1、建模：OpenGL圖形庫除了提供基本的點、線、多邊形的繪制函數外，還提供了復雜的三維物體（球、錐、多面體、茶壺等）以及復雜曲線和曲面繪制函數。

2、變換：OpenGL圖形庫的變換包括基本變換和投影變換。基本變換有平移、旋轉、縮放、鏡像四種變換，投影變換有平行投影（又稱正射投影）和透視投 影兩種變換。其變換方法有利于減少算法的運行時間，提高三維圖形的顯示速度。

3、顏色模式設置：OpenGL顏色模式有兩種，即RGBA模式和顏色索引（Color Index）。

4、光照和材質設置：OpenGL光有自發光（Emitted Light）、環境光（Ambient Light）、漫反射光（Diffuse Light）和高光（Specular Light）。材質是用光反射率來表示。場景（Scene）中物體最終反映到人眼的顏色是光的紅綠藍分量與材質紅綠藍分量的反射率相乘后形成的顏色。

5、紋理映射（Texture Mapping）。利用OpenGL紋理映射功能可以十分逼真地表達物體表面細節。

6、位圖顯示和圖象增強圖象功能除了基本的拷貝和像素讀寫外，還提供融合（Blending）、抗鋸齒（反走樣）（Antialiasing）和霧（fog）的特殊圖象效果處理。以上三條可使被仿真物更具真實感，增強圖形顯示的效果。

7、雙緩存動畫（Double Buffering）雙緩存即前臺緩存和后臺緩存，簡言之，后臺緩存計算場景、生成畫面，前臺緩存顯示后臺緩存已畫好的畫面。

2、OpenGL環境配置

① OpenGL的組成部分

————先來看一篇引用文章（OpenGL的前生今世）

gl庫是核心庫，gl中包含了最基本的3D函數，可以再本地電腦中的： C:\Program Files (x86)\ Microsoft SDKs\Windows \v7.0A\Include\gl 路徑下找到gl.h頭文件，打開后可以看到其中定義的上百個相關函數。

glu是實用庫，包含有43個函數，函數名的前綴為glu。glu 為了減輕繁重的編程工作，glu對gl中的函數進行部分封裝，glu函數通過調用核心庫的函數，為開發者提供相對簡單的用法，實現一些較為復雜的操作。如果算術好，在不使用glu庫的情況下，使用gl庫可以實現同樣的效果。

gult：OpenGL工具庫 OpenGL Utility Toolkit。 glut是基本的窗口界面，是獨立于gl和glu的，如果不喜歡用glut可使用MFC和Win32窗口等代替。但是glut是跨平臺的，這就保證了我們編出的程序具有跨平臺性，而使用MFC或Win32只能在windows操作系統上使用。

主要包括窗口操作函數，窗口初始化、窗口大小、窗口位置等函數；回調函數：響應刷新消息、鍵盤消息、鼠標消息等等。 這個頭文件自動包含了gl.h和glu.h，編程時不必再次包含它們。

GLUT或者FREEGLUT主要是1.0的基本函數功能；GLEW是使用OPENGL2.0之后的一個工具函數。不同的顯卡公司，也會發布一些只有自家顯卡才支持的擴展函數，你要想用這數涵數，不得不去尋找最新的glext.h,有了GLEW擴展庫，你就再也不用為找不到函數的接口而煩惱，因為GLEW能自動識別你的平臺所支持的全部OpenGL高級擴展函數。也就是說，只要包含一個glew.h頭文件，你就能使用gl,glu,glext,wgl,glx的全部函數。

glad和glew的作用相同，可看做它的升級版。

GLFW無愧于其號稱的lightweight的OpenGL框架，一個頭文件，很少量的API，就完成了任務。GLFW的開發目的是用于替代glut的，從代碼和功能上來看，我想它已經完全的完成了任務。它是一個輕量級的，開源的，跨平臺的library。支持OpenGL及OpenGL ES，用來管理窗口，讀取輸入，處理事件等。因為OpenGL沒有窗口管理的功能，所以很多熱心的人寫了工具來支持這些功能，比如早期的glut，現在的freeglut等。那么GLFW有何優勢呢？glut太老了，最后一個版本還是90年代的。freeglut完全兼容glut，算是glut的代替品，功能齊全，但是bug太多。穩定性也不好（不是我說的?。珿LFW應運而生。并且glfw也是跨平臺的~！

glfw可以看做是freeglut的升級版，freeglut可以看做是glut的升級版

綜上所述，為了安裝一個OpenGL，你需要一個3D函數庫和一個窗口管理庫。

3D函數庫可選：gl&glu，升級版glew，再升級glad。

窗口管理庫可選：glut，升級版freeglut，再升級glfw。

② 窗口管理庫GLFW的安裝

GLFW官網下載：https://www.glfw.org/download.html

windows一般下載 ，32-bit.。此處32和64指的不是本機器的位數，而是生成目標的位數。 windows pre-compiled binaries，為windows預編譯版本

整理所需文件到另一個文件夾：需要include文件夾和本機對應版本的"lib-vc20**"文件夾。如我的vs是2019，就復制include和lib-vc2019。

打開VS2019，新建一個c++win32控制臺項目

依次點擊“視圖" —>“屬性頁”, 在vc++目錄，“包含目錄”和“庫目錄”分別添加解壓復制后的Incude和lib目錄。 注意路徑。

在 “連接器” ->“附加依賴項”中添加“opengl32.lib”和"glfw3.lib"，用分號隔開

在在源文件中添加如下代碼測試環境

#include int main(void) { GLFWwindow* window; /* Initialize the library */ if (!glfwInit()) return -1; /* Create a windowed mode window and its OpenGL context */ window = glfwCreateWindow(640, 480, "Hello World", NULL, NULL); if (!window) { glfwTerminate(); return -1; } /* Make the window's context current */ glfwMakeContextCurrent(window); /* Loop until the user closes the window */ while (!glfwWindowShouldClose(window)) { /* Render here */ glClear(GL_COLOR_BUFFER_BIT); glBegin(GL_TRIANGLES); glVertex2d(0.5f, 0.5f); glVertex2d(-0.5f, -0.5f); glVertex2d(0.5f, -0.5f); glEnd(); /* Swap front and back buffers */ glfwSwapBuffers(window); /* Poll for and process events */ glfwPollEvents(); } glfwTerminate(); return 0; }

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

③3D函數庫 glad的安裝

glad官網下載：https://glad.dav1d.de/

語言選擇C/C++，在API選項中，選擇3.3以上的OpenGL(gl)版本（因為glfw不支持更早的版本，>=3.3都可以，具體可以看顯卡支持到哪個版本 ）。

之后將模式(Profile)設置為Core，并且保證生成加載器(Generate a loader)的選項是選中的。

現在可以先（暫時）忽略拓展(Extensions)中的內容。

都選擇完之后，點擊生成(Generate)按鈕來生成庫文件。

下載glad.zip文件解壓，就可以得到我們需要的include\glad\ glad.h、include\KHR\ khrplatform.h和src\ glad.c這3個文件

進入VS2019項目，在項目屬性 ----> C/C++ —> 附加包含目錄 —> your_path\glad\include

最后在項目中添加glad.c 文件

以下代碼測試是否安裝成功

#include //這個必須放在GLFW之前 #include #include void framebuffer_size_callback(GLFWwindow* window, int width, int height); void processInput(GLFWwindow* window); // settings const unsigned int SCR_WIDTH = 800; const unsigned int SCR_HEIGHT = 600; 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, 1.0);\n" "}

#include //這個必須放在GLFW之前 #include #include void framebuffer_size_callback(GLFWwindow* window, int width, int height); void processInput(GLFWwindow* window); // settings const unsigned int SCR_WIDTH = 800; const unsigned int SCR_HEIGHT = 600; 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, 1.0);\n" "}\0"; 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\0"; int main() { // glfw: initialize and configure // ------------------------------ glfwInit(); //glfw 初始化 //設置OpenGL版本等信息 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 // glfw window creation // -------------------- //創建GLFW窗口 GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL); if (window == NULL) { std::cout << "Failed to create GLFW window" << std::endl; glfwTerminate(); return -1; } //設置當前上下文 glfwMakeContextCurrent(window); glfwSetFramebufferSizeCallback(window, framebuffer_size_callback); // glad: load all OpenGL function pointers // --------------------------------------- //把OpenGL的函數指針導入給GLAD if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) { std::cout << "Failed to initialize GLAD" << std::endl; return -1; } // build and compile our shader program // ------------------------------------ // vertex shader 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 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 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); // set up vertex data (and buffer(s)) and configure vertex attributes // ------------------------------------------------------------------ float vertices[] = { 0.5f, 0.5f, 0.0f, // top right 0.5f, -0.5f, 0.0f, // bottom right -0.5f, -0.5f, 0.0f, // bottom left -0.5f, 0.5f, 0.0f // top left }; unsigned int indices[] = { // note that we start from 0! 0, 1, 3, // first Triangle 1, 2, 3 // second Triangle }; unsigned int VBO, VAO, EBO; glGenVertexArrays(1, &VAO); glGenBuffers(1, &VBO); glGenBuffers(1, &EBO); // bind the Vertex Array Object first, then bind and set vertex buffer(s), and then configure vertex attributes(s). 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); glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0); glEnableVertexAttribArray(0); // note that this is allowed, the call to glVertexAttribPointer registered VBO as the vertex attribute's bound vertex buffer object so afterwards we can safely unbind glBindBuffer(GL_ARRAY_BUFFER, 0); // remember: do NOT unbind the EBO while a VAO is active as the bound element buffer object IS stored in the VAO; keep the EBO bound. //glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0); // You can unbind the VAO afterwards so other VAO calls won't accidentally modify this VAO, but this rarely happens. Modifying other // VAOs requires a call to glBindVertexArray anyways so we generally don't unbind VAOs (nor VBOs) when it's not directly necessary. glBindVertexArray(0); // uncomment this call to draw in wireframe polygons. //glPolygonMode(GL_FRONT_AND_BACK, GL_LINE); // render loop // ----------- //循環渲染 while (!glfwWindowShouldClose(window)) { // input // ----- processInput(window); // render // ------ glClearColor(0.2f, 0.3f, 0.3f, 1.0f); glClear(GL_COLOR_BUFFER_BIT); // draw our first triangle glUseProgram(shaderProgram); glBindVertexArray(VAO); // seeing as we only have a single VAO there's no need to bind it every time, but we'll do so to keep things a bit more organized //glDrawArrays(GL_TRIANGLES, 0, 6); glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0); // glBindVertexArray(0); // no need to unbind it every time // glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.) // ------------------------------------------------------------------------------- //交換緩存 glfwSwapBuffers(window); //事件處理 glfwPollEvents(); } // optional: de-allocate all resources once they've outlived their purpose: // ------------------------------------------------------------------------ glDeleteVertexArrays(1, &VAO); glDeleteBuffers(1, &VBO); glDeleteBuffers(1, &EBO); // glfw: terminate, clearing all previously allocated GLFW resources. // ------------------------------------------------------------------ //停止 glfwTerminate(); return 0; } // process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly // --------------------------------------------------------------------------------------------------------- //輸入處理函數 void processInput(GLFWwindow* window) { if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS) glfwSetWindowShouldClose(window, true); } // glfw: whenever the window size changed (by OS or user resize) this callback function executes //窗口大小設置回調函數 // --------------------------------------------------------------------------------------------- void framebuffer_size_callback(GLFWwindow* window, int width, int height) { // make sure the viewport matches the new window dimensions; note that width and // height will be significantly larger than specified on retina displays. glViewport(0, 0, width, height); }

"; 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

#include //這個必須放在GLFW之前 #include #include void framebuffer_size_callback(GLFWwindow* window, int width, int height); void processInput(GLFWwindow* window); // settings const unsigned int SCR_WIDTH = 800; const unsigned int SCR_HEIGHT = 600; 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, 1.0);\n" "}\0"; 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\0"; int main() { // glfw: initialize and configure // ------------------------------ glfwInit(); //glfw 初始化 //設置OpenGL版本等信息 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 // glfw window creation // -------------------- //創建GLFW窗口 GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL); if (window == NULL) { std::cout << "Failed to create GLFW window" << std::endl; glfwTerminate(); return -1; } //設置當前上下文 glfwMakeContextCurrent(window); glfwSetFramebufferSizeCallback(window, framebuffer_size_callback); // glad: load all OpenGL function pointers // --------------------------------------- //把OpenGL的函數指針導入給GLAD if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) { std::cout << "Failed to initialize GLAD" << std::endl; return -1; } // build and compile our shader program // ------------------------------------ // vertex shader 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 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 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); // set up vertex data (and buffer(s)) and configure vertex attributes // ------------------------------------------------------------------ float vertices[] = { 0.5f, 0.5f, 0.0f, // top right 0.5f, -0.5f, 0.0f, // bottom right -0.5f, -0.5f, 0.0f, // bottom left -0.5f, 0.5f, 0.0f // top left }; unsigned int indices[] = { // note that we start from 0! 0, 1, 3, // first Triangle 1, 2, 3 // second Triangle }; unsigned int VBO, VAO, EBO; glGenVertexArrays(1, &VAO); glGenBuffers(1, &VBO); glGenBuffers(1, &EBO); // bind the Vertex Array Object first, then bind and set vertex buffer(s), and then configure vertex attributes(s). 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); glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0); glEnableVertexAttribArray(0); // note that this is allowed, the call to glVertexAttribPointer registered VBO as the vertex attribute's bound vertex buffer object so afterwards we can safely unbind glBindBuffer(GL_ARRAY_BUFFER, 0); // remember: do NOT unbind the EBO while a VAO is active as the bound element buffer object IS stored in the VAO; keep the EBO bound. //glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0); // You can unbind the VAO afterwards so other VAO calls won't accidentally modify this VAO, but this rarely happens. Modifying other // VAOs requires a call to glBindVertexArray anyways so we generally don't unbind VAOs (nor VBOs) when it's not directly necessary. glBindVertexArray(0); // uncomment this call to draw in wireframe polygons. //glPolygonMode(GL_FRONT_AND_BACK, GL_LINE); // render loop // ----------- //循環渲染 while (!glfwWindowShouldClose(window)) { // input // ----- processInput(window); // render // ------ glClearColor(0.2f, 0.3f, 0.3f, 1.0f); glClear(GL_COLOR_BUFFER_BIT); // draw our first triangle glUseProgram(shaderProgram); glBindVertexArray(VAO); // seeing as we only have a single VAO there's no need to bind it every time, but we'll do so to keep things a bit more organized //glDrawArrays(GL_TRIANGLES, 0, 6); glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0); // glBindVertexArray(0); // no need to unbind it every time // glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.) // ------------------------------------------------------------------------------- //交換緩存 glfwSwapBuffers(window); //事件處理 glfwPollEvents(); } // optional: de-allocate all resources once they've outlived their purpose: // ------------------------------------------------------------------------ glDeleteVertexArrays(1, &VAO); glDeleteBuffers(1, &VBO); glDeleteBuffers(1, &EBO); // glfw: terminate, clearing all previously allocated GLFW resources. // ------------------------------------------------------------------ //停止 glfwTerminate(); return 0; } // process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly // --------------------------------------------------------------------------------------------------------- //輸入處理函數 void processInput(GLFWwindow* window) { if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS) glfwSetWindowShouldClose(window, true); } // glfw: whenever the window size changed (by OS or user resize) this callback function executes //窗口大小設置回調函數 // --------------------------------------------------------------------------------------------- void framebuffer_size_callback(GLFWwindow* window, int width, int height) { // make sure the viewport matches the new window dimensions; note that width and // height will be significantly larger than specified on retina displays. glViewport(0, 0, width, height); }

"; int main() { // glfw: initialize and configure // ------------------------------ glfwInit(); //glfw 初始化 //設置OpenGL版本等信息 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 // glfw window creation // -------------------- //創建GLFW窗口 GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL); if (window == NULL) { std::cout << "Failed to create GLFW window" << std::endl; glfwTerminate(); return -1; } //設置當前上下文 glfwMakeContextCurrent(window); glfwSetFramebufferSizeCallback(window, framebuffer_size_callback); // glad: load all OpenGL function pointers // --------------------------------------- //把OpenGL的函數指針導入給GLAD if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) { std::cout << "Failed to initialize GLAD" << std::endl; return -1; } // build and compile our shader program // ------------------------------------ // vertex shader 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 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 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); // set up vertex data (and buffer(s)) and configure vertex attributes // ------------------------------------------------------------------ float vertices[] = { 0.5f, 0.5f, 0.0f, // top right 0.5f, -0.5f, 0.0f, // bottom right -0.5f, -0.5f, 0.0f, // bottom left -0.5f, 0.5f, 0.0f // top left }; unsigned int indices[] = { // note that we start from 0! 0, 1, 3, // first Triangle 1, 2, 3 // second Triangle }; unsigned int VBO, VAO, EBO; glGenVertexArrays(1, &VAO); glGenBuffers(1, &VBO); glGenBuffers(1, &EBO); // bind the Vertex Array Object first, then bind and set vertex buffer(s), and then configure vertex attributes(s). 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); glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0); glEnableVertexAttribArray(0); // note that this is allowed, the call to glVertexAttribPointer registered VBO as the vertex attribute's bound vertex buffer object so afterwards we can safely unbind glBindBuffer(GL_ARRAY_BUFFER, 0); // remember: do NOT unbind the EBO while a VAO is active as the bound element buffer object IS stored in the VAO; keep the EBO bound. //glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0); // You can unbind the VAO afterwards so other VAO calls won't accidentally modify this VAO, but this rarely happens. Modifying other // VAOs requires a call to glBindVertexArray anyways so we generally don't unbind VAOs (nor VBOs) when it's not directly necessary. glBindVertexArray(0); // uncomment this call to draw in wireframe polygons. //glPolygonMode(GL_FRONT_AND_BACK, GL_LINE); // render loop // ----------- //循環渲染 while (!glfwWindowShouldClose(window)) { // input // ----- processInput(window); // render // ------ glClearColor(0.2f, 0.3f, 0.3f, 1.0f); glClear(GL_COLOR_BUFFER_BIT); // draw our first triangle glUseProgram(shaderProgram); glBindVertexArray(VAO); // seeing as we only have a single VAO there's no need to bind it every time, but we'll do so to keep things a bit more organized //glDrawArrays(GL_TRIANGLES, 0, 6); glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0); // glBindVertexArray(0); // no need to unbind it every time // glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.) // ------------------------------------------------------------------------------- //交換緩存 glfwSwapBuffers(window); //事件處理 glfwPollEvents(); } // optional: de-allocate all resources once they've outlived their purpose: // ------------------------------------------------------------------------ glDeleteVertexArrays(1, &VAO); glDeleteBuffers(1, &VBO); glDeleteBuffers(1, &EBO); // glfw: terminate, clearing all previously allocated GLFW resources. // ------------------------------------------------------------------ //停止 glfwTerminate(); return 0; } // process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly // --------------------------------------------------------------------------------------------------------- //輸入處理函數 void processInput(GLFWwindow* window) { if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS) glfwSetWindowShouldClose(window, true); } // glfw: whenever the window size changed (by OS or user resize) this callback function executes //窗口大小設置回調函數 // --------------------------------------------------------------------------------------------- void framebuffer_size_callback(GLFWwindow* window, int width, int height) { // make sure the viewport matches the new window dimensions; note that width and // height will be significantly larger than specified on retina displays. glViewport(0, 0, width, height); }

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

61

62

63

64

65

66

67

68

69

70

71

72

73

74

75

76

77

78

79

80

81

82

83

84

85

86

87

88

89

90

91

92

93

94

95

96

97

98

99

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

152

153

154

155

156

157

158

159

160

161

162

163

164

165

166

167

168

169

170

171

172

173

174

175

176

177

178

179

180

181

182

183

184

185

186

187

188

189

190

191

192

193

194

195

196

197

198

199

200

201

202

203

204

205

206

API OpenGL Windows

版權聲明：本文內容由網絡用戶投稿，版權歸原作者所有，本站不擁有其著作權，亦不承擔相應法律責任。如果您發現本站中有涉嫌抄襲或描述失實的內容，請聯系我們jiasou666@gmail.com 處理，核實后本網站將在24小時內刪除侵權內容。

版權聲明：本文內容由網絡用戶投稿，版權歸原作者所有，本站不擁有其著作權，亦不承擔相應法律責任。如果您發現本站中有涉嫌抄襲或描述失實的內容，請聯系我們jiasou666@gmail.com 處理，核實后本網站將在24小時內刪除侵權內容。