VAO 不渲染

Question

我创建了一个加载器类来加载 V.A.Os 纹理等，但是当我使用这个方法时

GLuint Loader::loadToVAO(GLfloat* vertices)
{
    GLuint VertexArrayID;
    glGenVertexArrays(1, &VertexArrayID);
    glBindVertexArray(VertexArrayID);

    GLuint vertexbuffer;
    glGenBuffers(1, &vertexbuffer);
    glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
    return vertexbuffer;
}

这里没有渲染任何东西是我的渲染代码：

window.createWindow();

GLfloat vertices[] = {
    -1.0f, -1.0f, 0.0f,
    1.0f, -1.0f, 0.0f,
    0.0f,  1.0f, 0.0f,
};

GLuint vertexbuffer = loader.loadToVAO(vertices);

glClearColor(0, 1, 1, 0);

// It works fine when i generate the vao in the main method but not in the loader class
GLuint vertexbuffer1;
glGenBuffers(1, &vertexbuffer1);
glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer1);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

std::cout << vertexbuffer1 << std::endl;
std::cout << vertexbuffer << std::endl;

while (!window.shouldClose())
{
    window.clearWindow();

    // render here
    glEnableVertexAttribArray(0);
    glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer1);
    glVertexAttribPointer(
        0,                  // attribute 0. No particular reason for 0, but must match the layout in the shader.
        3,                  // size
        GL_FLOAT,           // type
        GL_FALSE,           // normalized?
        0,                  // stride
        (void*)0            // array buffer offset
    );
    // Draw the triangle !
    glDrawArrays(GL_TRIANGLES, 0, 3); // Starting from vertex 0; 3 vertices total -> 1 triangle
    glDisableVertexAttribArray(0);

    window.updateWindow();
}

return 0;

当我尝试渲染 vertexbuffer1（在 main 方法中加载的那个）时它渲染得很好，但是顶点缓冲区没有渲染任何东西。 任何帮助将不胜感激

编辑： 这是我试图遵循的教程 - http://www.opengl-tutorial.org/

Answer 1

您在函数内的指针类型上使用sizeof，这几乎肯定不是您想要的。数组在 C 和 C++ 等语言中不是 first-class citizens，它们衰减为指针，指针不携带有关它们存储的数据量的信息。您想要做的是将数组的大小作为附加参数传递：

GLuint Loader::loadToVAO(GLfloat* vertices, size_t num_vertices)
{
    GLuint VertexArrayID;
    glGenVertexArrays(1, &VertexArrayID);
    glBindVertexArray(VertexArrayID);

    GLuint vertexbuffer;
    glGenBuffers(1, &vertexbuffer);
    glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(*vertices) * num_vertices, vertices, 
    GL_STATIC_DRAW);
    return vertexbuffer;
}

然后在你的主函数中：

GLuint vertexbuffer = loader.loadToVAO(vertices, sizeof(vertices) / sizeof(vertices[0]));

我鼓励您阅读更多有关该主题的信息here。