【VBO+VAO】使用OpenGL绘制简单三角形

参考：LearnOpenGL CN：https://learnopengl-cn.github.io/01%20Getting%20started/04%20Hello%20Triangle/

使用OpenGL绘制简单三角形

#include
#include 
#include 

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";

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";

void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
    glViewport(0, 0, width, height);
}

void processInput(GLFWwindow* window)
{
    if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
        glfwSetWindowShouldClose(window, true);
}

int main()
{

    glfwInit();
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);//将主版本号(Major)和次版本号(Minor)都设为3
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);//告诉GLFW我们使用的是核心模式(Core-profile)

    GLFWwindow* window = glfwCreateWindow(800, 600, "LearnOpenGL", NULL, NULL);
    
    if (window == NULL)
    {
        std::cout << "Failed to create GLFW window" << std::endl;
        glfwTerminate();
        return -1;
    }
    glfwMakeContextCurrent(window);

    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))//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。
    {
        std::cout << "Failed to initialize GLAD" << std::endl;
        return -1;
    }

    glViewport(0, 0, 800, 600); 

    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
 
    unsigned int vertexShader;
    vertexShader = glCreateShader(GL_VERTEX_SHADER);

    glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
    glCompileShader(vertexShader);


    unsigned int fragmentShader;
    fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
    glCompileShader(fragmentShader);


    unsigned int shaderProgram;
    shaderProgram = glCreateProgram();
    glAttachShader(shaderProgram, vertexShader);
    glAttachShader(shaderProgram, fragmentShader);
    glLinkProgram(shaderProgram);

    //glUseProgram(shaderProgram);

    glDeleteShader(vertexShader);
    glDeleteShader(fragmentShader);

    float vertices[] = {
    -0.5f, -0.5f, 0.0f,
     0.5f, -0.5f, 0.0f,
     0.0f,  0.5f, 0.0f
    };

    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);


    unsigned int VBO, VAO;
    glGenVertexArrays(1, &VAO);
    glGenBuffers(1, &VBO);
    glBindVertexArray(VAO); {

        glBindBuffer(GL_ARRAY_BUFFER, VBO);
        glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

        glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
        glEnableVertexAttribArray(0);

    }
    glBindBuffer(GL_ARRAY_BUFFER, 0);
    glBindVertexArray(0);


    while (!glfwWindowShouldClose(window))//我们需要在程序中添加一个while循环，我们可以把它称之为渲染循环(Render Loop)，它能在我们让GLFW退出前一直保持运行
    {

        // 输入
        processInput(window);

        //渲染指令QAQ
        glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT);
        glUseProgram(shaderProgram);
        glBindVertexArray(VAO);
        glDrawArrays(GL_TRIANGLES, 0, 3);

        //检查并调用事件，交换缓冲
        glfwSwapBuffers(window);
        glfwPollEvents();

    }

    glfwTerminate();
    return 0;
}

实现效果