【OpenGL】知识点

VAO

和webgl一致
给个完整案例，可以对比案例：WebGL中VAO调用，是一致的

void prepareSingleBuffer() {//1 准备positions colors数据float positions[] = {-0.5f, -0.5f, 0.0f,0.5f, -0.5f, 0.0f,0.0f,  0.5f, 0.0f};float colors[] = {1.0f, 0.0f, 0.0f,0.0f, 1.0f, 0.0f,0.0f,  0.0f, 1.0f};//2 使用数据生成两个vbo posVbo， colorVboGLuint posVbo, colorVbo;glGenBuffers(1, &posVbo);glGenBuffers(1, &colorVbo);glBindBuffer(GL_ARRAY_BUFFER, posVbo);glBufferData(GL_ARRAY_BUFFER, sizeof(positions), positions, GL_STATIC_DRAW);glBindBuffer(GL_ARRAY_BUFFER, colorVbo);glBufferData(GL_ARRAY_BUFFER, sizeof(colors), colors, GL_STATIC_DRAW);//3 生成vao并且绑定GLuint vao = 0;glGenVertexArrays(1, &vao);glBindVertexArray(vao);//4 分别将位置/颜色属性的描述信息加入vao当中//4.1描述位置属性glBindBuffer(GL_ARRAY_BUFFER, posVbo);//只有绑定了posVbo，下面的属性描述才会与此vbo相关glEnableVertexAttribArray(0);glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);//4.2 描述颜色属性glBindBuffer(GL_ARRAY_BUFFER, colorVbo);glEnableVertexAttribArray(1);glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);glBindVertexArray(0);
}

顶点着色器

在这里插入图片描述
460版本，看到这里新东西layout

片元着色器

在这里插入图片描述

Shader编译与链接

和webgl一致

void prepareShader() {//1 完成vs与fs的源代码，并且装入字符串const char* vertexShaderSource ="#version 460 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";//2 创建Shader程序（vs、fs）GLuint vertex, fragment;vertex = glCreateShader(GL_VERTEX_SHADER);fragment = glCreateShader(GL_FRAGMENT_SHADER);//3 为shader程序输入shader代码glShaderSource(vertex, 1, &vertexShaderSource, NULL);glShaderSource(fragment, 1, &fragmentShaderSource, NULL);int success = 0;char infoLog[1024];//4 执行shader代码编译 glCompileShader(vertex);//检查vertex编译结果glGetShaderiv(vertex, GL_COMPILE_STATUS, &success);if (!success) {glGetShaderInfoLog(vertex, 1024, NULL, infoLog);std::cout << "Error: SHADER COMPILE ERROR --VERTEX" << "\n" << infoLog << std::endl;}glCompileShader(fragment);//检查fragment编译结果glGetShaderiv(fragment, GL_COMPILE_STATUS, &success);if (!success) {glGetShaderInfoLog(fragment, 1024, NULL, infoLog);std::cout << "Error: SHADER COMPILE ERROR --FRAGMENT" << "\n" << infoLog << std::endl;}//5 创建一个Program壳子GLuint program = 0;program = glCreateProgram();//6 将vs与fs编译好的结果放到program这个壳子里glAttachShader(program, vertex);glAttachShader(program, fragment);//7 执行program的链接操作，形成最终可执行shader程序glLinkProgram(program);//检查链接错误glGetProgramiv(program, GL_LINK_STATUS, &success);if (!success) {glGetProgramInfoLog(program, 1024, NULL, infoLog);std::cout << "Error: SHADER LINK ERROR " << "\n" << infoLog << std::endl;}//清理glDeleteShader(vertex);glDeleteShader(fragment);
}

绘制

和webgl一致

void render() {//执行opengl画布清理操作glClear(GL_COLOR_BUFFER_BIT);//1 绑定当前的programglUseProgram(program);//2 绑定当前的vaoglBindVertexArray(vao);//3 发出绘制指令//	glDrawArrays(GL_LINE_STRIP, 0, 6);glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_INT, 0);glBindVertexArray(0);
}