OpenGL_6:用两个VBO和VAO分别画2个三角形

#include 
#include 
#include 

const char *vertexShaderSource =
        "#version 330 core\n"
                "layout (location = 0) in vec3 aPos;\n"
                "void main(){\n"
                "gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0f);\n"
                "}\n\0";

const char *fragmentShaderSource =
        "#version 330 core\n"
                "out vec4 FragColor;\n"
                "void main(){\n"
                "FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);\n"
                "}\n\0";

void processInput(GLFWwindow *glfWwindow);
void framebuffer_size_callback(GLFWwindow* glfWwindow, int width, int height);

int main() {

    glfwInit();
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

    GLFWwindow *glfWwindow = glfwCreateWindow(800, 600, "Square", NULL, NULL);
    if (NULL == glfWwindow){
        printf("Failed to create window \n");
        glfwTerminate();
        return -1;
    }
    glfwMakeContextCurrent(glfWwindow);
    glfwSetFramebufferSizeCallback(glfWwindow, framebuffer_size_callback);

    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)){
        printf("Failed to initialize GLAD\n");
    }

    unsigned int vertexShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
    glCompileShader(vertexShader);

    int success;
    char infoLog[512];
    glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
    if (!success){
        glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
        printf("Failed to compile vertexShader:%s \n", infoLog);
    }

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

    glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);
    if (!success){
        glGetShaderInfoLog(fragmentShader, 512, NULL, infoLog);
        printf("Failed to compile fragmentShader:%s \n", infoLog);
    }

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

    glGetShaderiv(shaderProgram, GL_LINK_STATUS, &success);
    if (!success){
        glGetProgramInfoLog(shaderProgram, 512, NULL, infoLog);
        printf("Failed to link shaderProgram:%s \n", infoLog);
    }

    glDeleteShader(vertexShader);
    glDeleteShader(fragmentShader);

    float vertices_1[] = {
            // first triangle
            -0.9f, -0.5f, 0.0f,  // left
            -0.0f, -0.5f, 0.0f,  // right
            -0.45f, 0.5f, 0.0f  // top
    };

    float vertices_2[] = {
            // second triangle
            0.0f, -0.5f, 0.0f,  // left
            0.9f, -0.5f, 0.0f,  // right
            0.45f, 0.5f, 0.0f   // top
    };

    unsigned int VBO[2], VAO[2];
    glGenVertexArrays(2, VAO);
    glGenBuffers(2, VBO);

    glBindVertexArray(VAO[0]);
    glBindBuffer(GL_ARRAY_BUFFER, VBO[0]);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices_1), vertices_1, GL_STATIC_DRAW);

    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);
//    glBindVertexArray(0);  //no need to unbind at all as we directly bind a different VAO the next few lines


//    glBindBuffer(GL_ARRAY_BUFFER, 0);


    glBindVertexArray(VAO[1]);
    glBindBuffer(GL_ARRAY_BUFFER, VBO[1]);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices_2), vertices_2, GL_STATIC_DRAW);

    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);
    // glBindVertexArray(0); // not really necessary as well, but beware of calls that could affect VAOs while this one is bound (like binding element buffer objects, or enabling/disabling vertex attributes)

//    glBindBuffer(GL_ARRAY_BUFFER, 0);



    /**
     * 当目标是GL_ELEMENT_ARRAY_BUFFER的时候，VAO会储存glBindBuffer的函数调用。
     * 这也意味着它也会储存解绑调用，所以确保你没有在解绑VAO之前解绑索引数组缓冲，
     * 否则它就没有这个EBO配置了。
     * */
    //glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);

    //glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);

    while (!glfwWindowShouldClose(glfWwindow)){

        processInput(glfWwindow);

        glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT);

        glUseProgram(shaderProgram);

        glBindVertexArray(VAO[0]);
        glDrawArrays(GL_TRIANGLES, 0, 3);

        glBindVertexArray(VAO[1]);
        glDrawArrays(GL_TRIANGLES, 0, 3);

//        glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);

        glfwSwapBuffers(glfWwindow);
        glfwPollEvents();
    }

    glDeleteVertexArrays(2, VAO);
    glDeleteBuffers(2, VBO);

    glfwTerminate();
    return 0;
}

void processInput(GLFWwindow *glfWwindow){
    if (glfwGetKey(glfWwindow, GLFW_KEY_ESCAPE))
        glfwSetWindowShouldClose(glfWwindow, GLFW_TRUE);
}

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

运行结果: