c++ - Xcode8.2.1 上的 OpenGL - 顶点未显示在窗口中

Question

我正在学习 c++ 和 openGL 并让它在我的 MacBook Xcode 中工作。我有这段代码:

#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <stdio.h>

int main ()
{
    GLFWwindow* window = NULL;
    const GLubyte* renderer;
    const GLubyte* version;

    if (!glfwInit ()) {
        fprintf (stderr, "ERROR: could not start GLFW3\n");
        return 1;
    }

    glfwWindowHint (GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint (GLFW_CONTEXT_VERSION_MINOR, 2);
    glfwWindowHint (GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
    glfwWindowHint (GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

    window = glfwCreateWindow (640, 480, "OpenGL", NULL, NULL);
    if (!window) {
        fprintf (stderr, "ERROR: could not open window with GLFW3\n");
        glfwTerminate ();
        return 1;
    }
    glfwMakeContextCurrent (window);

    /* start GLEW extension handler */
    glewExperimental = GL_TRUE;
    glewInit ();

    glEnable (GL_DEPTH_TEST);
    glDepthFunc (GL_LESS);

    GLfloat 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
    };
    GLuint indices[] = {  // Note that we start from 0!
        0, 1, 3,  // First Triangle
        1, 2, 3   // Second Triangle
    };
    GLuint VBO, VAO, EBO;
    glGenVertexArrays(1, &VAO);
    glGenBuffers(1, &VBO);
    glGenBuffers(1, &EBO);

    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(GLfloat), (GLvoid*)0);

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

    while (!glfwWindowShouldClose(window))
    {
        glfwPollEvents();

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

        glBindVertexArray(VAO);
        glDrawArrays(GL_TRIANGLES, 0, 6);
//        glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
        glBindVertexArray(0);

        glfwSwapBuffers(window);
    }

    glDeleteVertexArrays(1, &VAO);
    glDeleteBuffers(1, &VBO);
    glDeleteBuffers(1, &EBO);

    glfwTerminate ();
    return 0;
}

它成功地打开了窗口，没有错误，但是场景中没有绘制任何四边形或三角形。我确实尝试过:

glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);

在 while() 之前，但仍然没有。什么似乎不起作用？我 printf 下面是我使用的:

Renderer: Intel(R) Iris(TM) Graphics 6100
OpenGL version supported: 4.1 INTEL-10.22.25
glsl: 4.10

我该如何解决？

Update01

我有一个带有着色器的版本:

#include <iostream>
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <stdio.h>

const GLchar* vertexShaderSource = "#version 330 core\n"
"layout (location = 0) in vec3 position;\n"
"void main()\n"
"{\n"
"gl_Position = vec4(position.x, position.y, position.z, 1.0);\n"
"}\0";
const GLchar* fragmentShaderSource = "#version 330 core\n"
"out vec4 color;\n"
"void main()\n"
"{\n"
"color = vec4(1.0f, 0.5f, 0.2f, 1.0f);\n"
"}\n\0";

int main ()
{
    GLFWwindow* window = NULL;
    const GLubyte* renderer;
    const GLubyte* version;

    if (!glfwInit ()) {
        fprintf (stderr, "ERROR: could not start GLFW3\n");
        return 1;
    }

    glfwWindowHint (GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint (GLFW_CONTEXT_VERSION_MINOR, 2);
    glfwWindowHint (GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
    glfwWindowHint (GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

    window = glfwCreateWindow (640, 480, "OpenGL", NULL, NULL);
    if (!window) {
        fprintf (stderr, "ERROR: could not open window with GLFW3\n");
        glfwTerminate ();
        return 1;
    }
    glfwMakeContextCurrent (window);

    glewExperimental = GL_TRUE;
    glewInit ();

    glEnable (GL_DEPTH_TEST);
    glDepthFunc (GL_LESS);

    // Build and compile our shader program
    // Vertex shader
    GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
    glCompileShader(vertexShader);
    // Check for compile time errors
    GLint success;
    GLchar 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
    GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
    glCompileShader(fragmentShader);
    // Check for compile time 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
    GLuint 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);

    GLfloat 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
    };
    GLuint indices[] = {  // Note that we start from 0!
        0, 1, 3,  // First Triangle
        1, 2, 3   // Second Triangle
    };
    GLuint VBO, VAO, EBO;
    glGenVertexArrays(1, &VAO);
    glGenBuffers(1, &VBO);
    glGenBuffers(1, &EBO);

    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(GLfloat), (GLvoid*)0);
    glEnableVertexAttribArray(0);

    glBindBuffer(GL_ARRAY_BUFFER, 0); 

    glBindVertexArray(0); 

    glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
    while (!glfwWindowShouldClose(window))
    {
        glfwPollEvents();

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

        // Draw our first triangle
        glUseProgram(shaderProgram);
        glBindVertexArray(VAO);
//        glDrawArrays(GL_TRIANGLES, 0, 6);
        glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
        glBindVertexArray(0);

        // Swap the screen buffers
        glfwSwapBuffers(window);
    }

    glDeleteVertexArrays(1, &VAO);
    glDeleteBuffers(1, &VBO);
    glDeleteBuffers(1, &EBO);

    glfwTerminate ();
    return 0;
}

我仍然没有收到任何错误，四边形仍然没有显示。

Answer 1

我发现了问题。

就是这条线:

glEnable (GL_DEPTH_TEST);

使四边形不显示。我注释掉该行，然后一切正常。