Question

我正在尝试加载我在混合器中绘制的东西的.obj文件，并在我的GUI上显示它，但我对如何继续有点迷失。一些文档提供了有关某些功能的非常简要的信息。

这是我在编写时所遵循的tutorial。

我现在根本不知道如何在我的openGLWidget上绘图。

这是我的代码 - 我认为 - 应该显示我的gui，但它没有：

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    load_obj("/home/yalishanda/Desktop/car.obj", suzanne_vertices, suzanne_normals, suzanne_elements);

    //enable all vertices attributes
    for(int i=0;i<suzanne_vertices;i++)
    {
        glEnableVertexAttribArray(i);
    }

    GLuint buffer;
    glBindBuffer(GL_ARRAY_BUFFER, buffer);
    glVertexAttribPointer(
        0,
        4,
        GL_FLOAT,
        GL_FALSE,
        0,
        0
      );

     // glEnableVertexAttribArray(0);
      GLuint buffer2;
      glBindBuffer(GL_ARRAY_BUFFER, buffer2);
      glVertexAttribPointer(
        0,
        3,
        GL_FLOAT,           // the type of each element
        GL_FALSE,           // take our values as-is
        0,                  // no extra data between each position
        0                   // offset of first element
      );

      glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
      int size;
      glGetBufferParameteriv(GL_ELEMENT_ARRAY_BUFFER, GL_BUFFER_SIZE, &size);
      glDrawElements(GL_TRIANGLES, size/sizeof(GLushort), GL_UNSIGNED_SHORT, 0);

      paintGL();

}

MainWindow::~MainWindow()
{
    delete ui;
}


void MainWindow::load_obj(const char* filename, std::vector<QVector4D> &vertices, std::vector<QVector3D> &normals, std::vector<GLushort> &elements)
{
    std::ifstream in(filename, std::ios::in);
    if (!in)
    {
        std::cerr << "Cannot open " << filename << std::endl; exit(1);
    }

    std::string line;
    while (std::getline(in, line))
    {
        if (line.substr(0,2) == "v ")
        {
            std::istringstream s(line.substr(2));
            QVector4D v;
            //s >> v.x;
            //s >> v.y;
            //s >> v.z;
            //v.w = 1.0f;
            float helpValue;
            s>>helpValue;
            v.setX(helpValue);
            v.setY(helpValue);
            v.setZ(helpValue);
            v.setW(1.0f);
            vertices.push_back(v);
        }
        else if (line.substr(0,2) == "f ")
        {
            std::istringstream s(line.substr(2));
            GLushort a,b,c;
            s >> a; s >> b; s >> c;
            a--; b--; c--;
           elements.push_back(a); elements.push_back(b); elements.push_back(c);
        }
        else if (line[0] == '#')
        {
            /* ignoring this line */
        }
        else
        {
            /* ignoring this line */
        }
    }

    normals.resize(vertices.size(), QVector3D(0.0, 0.0, 0.0));
    for (int i = 0; i < elements.size(); i+=3)
    {
        GLushort ia = elements[i];
        GLushort ib = elements[i+1];
        GLushort ic = elements[i+2];

        QVector3D difference =  QVector3D::crossProduct(
        QVector3D(vertices[ib]) - QVector3D(vertices[ia]),
        QVector3D(vertices[ic]) - QVector3D(vertices[ia]) );

        QVector3D normal = difference.normalized();
        normals[ia] = normals[ib] = normals[ic] = normal;
    }
}

void MainWindow::initializeGL()
{
    glClearColor(0,0,0,1);
    glEnable(GL_DEPTH_TEST);
    glEnable(GL_LIGHT0);
    glEnable(GL_LIGHTING);
    glColorMaterial(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE);
    glEnable(GL_COLOR_MATERIAL);
}

void MainWindow::paintGL()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    //draw all the vertices
    // I guess that here I should select my openGL widget somehow and draw the vertices *on* it
    glBegin(GL_VERTEX4_BIT_PGI);
        for(int i=0; i<suzanne_vertices.size();i++)
        {
            glVertex3f(suzanne_vertices.at(i).x, suzanne_vertices.at(i).y, suzanne_vertices.at(i).z);
        }

    glEnd();
}

Answer 1

我认为首先你没有指定相机？

我从教程中获取了这个片段，

 glm::mat4 view = glm::lookAt(
    glm::vec3(0.0,  2.0, 4.0),   // eye
    glm::vec3(0.0,  0.0, 0.0),   // direction
    glm::vec3(0.0,  1.0, 0.0));  // up
  glm::mat4 projection = glm::perspective(45.0f, 1.0f*screen_width/screen_height, 0.1f, 100.0f);

OpenGL在开始时是一个非常痛苦的库，它要求管道完全正确以呈现正确的东西，其他它不会告诉你哪里出错。

此外，您可能想要禁用材质和灯光，并将渲染颜色设置为（让我们说是绿色），以便在开头看到某些内容，如果您的材料未正确设置，光也可能使一切都变黑。

openGL - 加载.obj并在GUI上绘制失败

1 个答案: