qopenglwidget trying to output to 3d model in format .obj .

[timob256]

trying to output to 3d model in format .obj .

I want to output a 3d model to QOpenGLWidget in obj format.

How to do it?? is there an example of "how to display a 3D model on the screen" ??

dialogokno.h

#ifndef DIALOGOKNO_H
#define DIALOGOKNO_H

#include <QMainWindow>
#include <QFile>
#include <QPushButton>
#include <QLabel>
#include <QSize>

#include <QApplication>
#include <QDesktopWidget>
#include <QRect>
#include <QDebug>
#include <QLineEdit>
#include <QGridLayout>
#include <QSpacerItem>
#include <QObject>
#include <QOpenGLWidget>

#include "myglwidget.h"

class DialogOkno : public QWidget
{
    Q_OBJECT

public:
    DialogOkno(QWidget *parent = 0);
    ~DialogOkno();

protected:
//    QWidget* centralWidget;

    QFile* file;         // загрузить файл
    QGridLayout* gl_layaout[4];
    QPushButton* b_load; // кнопка для выбора и загрузки файла
    QLabel* l_label[3];
    QLineEdit* le_edit[7];
    QSpacerItem* si_spacer[4];
};

#endif // DIALOGOKNO_H

glwidget.h

#ifndef MYGLWIDGET_H
#define MYGLWIDGET_H

#include <QOpenGLWidget>
#include <QDebug>

#include <iostream>
#include <sstream>
#include <string>
#include <fstream>
#include <vector>

class MyGLWidget : public QOpenGLWidget
{
    Q_OBJECT
public:
    MyGLWidget(QWidget* parent = nullptr);

    // Globals.
     std::vector<float> verticesVector; // Vector to read in vertex x, y and z values fromt the OBJ file.
     std::vector<int> facesVector; // Vector to read in face vertex indices from the OBJ file.
     float *vertices = NULL;  // Vertex array of the object x, y, z values.
    int *faces = NULL; // Face (triangle) vertex indices.
     int numIndices; // Number of face vertex indices.
     float Xangle = 0.0, Yangle = 0.0, Zangle = 0.0; // Angles to rotate the object.
    void loadOBJ(std::string fileName);

protected:
    void initializeGL();
    void resizeGL(int w, int h);
    void paintGL();
};

#endif // MYGLWIDGET_H

dialogokno.cpp

#include "dialogokno.h"

DialogOkno::DialogOkno(QWidget *parent)
    : QWidget(parent)
{
    MyGLWidget * openGL = new MyGLWidget(parent);

    // обявл элементы
    gl_layaout[0] = new QGridLayout(parent);
    gl_layaout[1] = new QGridLayout(parent);
    gl_layaout[2] = new QGridLayout(parent);

    gl_layaout[3] = new QGridLayout(parent);

    l_label[0] = new QLabel(parent);
    l_label[1] = new QLabel(parent);
    l_label[2] = new QLabel(parent);

    le_edit[0] = new QLineEdit(parent);
    le_edit[1] = new QLineEdit(parent);
    le_edit[2] = new QLineEdit(parent);
    le_edit[3] = new QLineEdit(parent);
    le_edit[4] = new QLineEdit(parent);
    le_edit[5] = new QLineEdit(parent);
    le_edit[6] = new QLineEdit(parent);

    // настройки элеметов (стилизация)

    // заполнение элементов
    l_label[0]->setText("hla_global");
    l_label[1]->setText("hla_local");
    l_label[2]->setText("logger");

    le_edit[0]->setText("server_ip_global");
    le_edit[1]->setText("server_port_global");

    le_edit[2]->setText("server_port_local");
    le_edit[3]->setText("server_port_local");

    le_edit[4]->setText("log");
    le_edit[5]->setText("log_period_ms");
    le_edit[6]->setText("log_size_in_mb");

    //разложение элементов по группам

    gl_layaout[0]->addWidget(l_label[0], 0, 0, 1, 1);
    gl_layaout[0]->addWidget(le_edit[0], 1, 0, 1, 1);
    gl_layaout[0]->addWidget(le_edit[1], 2, 0, 1, 1);

    gl_layaout[1]->addWidget(l_label[1], 0, 0, 1, 1);
    gl_layaout[1]->addWidget(le_edit[2], 1, 0, 1, 1);
    gl_layaout[1]->addWidget(le_edit[3], 2, 0, 1, 1);

    gl_layaout[2]->addWidget(l_label[2], 0, 0, 1, 1);
    gl_layaout[2]->addWidget(le_edit[4], 1, 0, 1, 1);
    gl_layaout[2]->addWidget(le_edit[5], 2, 0, 1, 1);
    gl_layaout[2]->addWidget(le_edit[6], 3, 0, 1, 1);


    gl_layaout[3]->addLayout(gl_layaout[0], 0, 0, 1, 1);

    si_spacer[0] = new QSpacerItem(120, 20, QSizePolicy::Expanding, QSizePolicy::Minimum);

    gl_layaout[3]->addItem(si_spacer[0], 0, 1, 1, 1);

    gl_layaout[3]->addLayout(gl_layaout[1], 0, 2, 1, 1);
    si_spacer[1] = new QSpacerItem(120, 20, QSizePolicy::Expanding, QSizePolicy::Minimum);
    gl_layaout[3]->addItem(si_spacer[1], 0, 3, 1, 1);
    si_spacer[2] = new QSpacerItem(20, 82, QSizePolicy::Minimum, QSizePolicy::Expanding);
    gl_layaout[3]->addItem(si_spacer[2],1, 0, 1, 1);
    gl_layaout[3]->addLayout(gl_layaout[2], 2, 0, 1, 1);
    si_spacer[3] = new QSpacerItem(20, 82, QSizePolicy::Minimum, QSizePolicy::Expanding);
    gl_layaout[3]->addItem(si_spacer[3], 3, 0, 1, 1);
    gl_layaout[3]->addWidget(openGL , 1, 1, 3, 3);

    this->setLayout(gl_layaout[3]);
}

DialogOkno::~DialogOkno()
{

}

main.cpp

#include "dialogokno.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QApplication::setAttribute(Qt::AA_ForceRasterWidgets, false);
    DialogOkno w;
    QDesktopWidget desktop;
    QRect rect = desktop.availableGeometry(desktop.primaryScreen()); // прямоугольник с размерами экрана
    QPoint center = rect.center(); //координаты центра экрана
    w.resize(center.x(), center.y());

    w.setWindowTitle("программа");
    w.show();

    return a.exec();
}

glwidget.cpp

#include "myglwidget.h"

MyGLWidget::MyGLWidget(QWidget * parent): QOpenGLWidget(parent)
{

}

void MyGLWidget::initializeGL()
{
    glEnableClientState(GL_VERTEX_ARRAY);

    glClearColor(1.0, 1.0, 1.0, 0.0);
}

void MyGLWidget::resizeGL(int w, int h)
{
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glMatrixMode(GL_MODELVIEW);
}

void MyGLWidget::paintGL()
{
    glClearColor(1.0, 1.0, 0.0, 0.0);

    // Read the external OBJ file into the internal vertex and face vectors.
    loadOBJ("gourd.obj");

    qDebug() << "tyt1";
    // Size the vertex array and copy into it x, y, z values from the vertex vector.
    vertices = new float[verticesVector.size()];
    for (int i = 0; i < verticesVector.size(); i++) vertices[i] = verticesVector[i];

    qDebug() << "tyt2";
    // Size the faces array and copy into it face index values from the face vector.
    faces = new int[facesVector.size()];
    for (int i = 0; i < facesVector.size(); i++) faces[i] = facesVector[i];
    numIndices = facesVector.size();

    glVertexPointer(3, GL_FLOAT, 0, vertices);

    qDebug() << "tyt3";
}

void MyGLWidget::loadOBJ(std::string fileName)
{
   std::string line;
   int count, vertexIndex1, vertexIndex2, vertexIndex3;
   float coordinateValue;
   char currentCharacter, previousCharacter;

   // Open the OBJ file.
   std::ifstream inFile(fileName.c_str(), std::ifstream::in);

   // Read successive lines.
   while (getline(inFile, line))
   {
      // Line has vertex data.
      if (line.substr(0, 2) == "v ")
      {
         // Initialize a string from the character after "v " to the end.
         std::istringstream currentString(line.substr(2));

         // Read x, y and z values. The (optional) w value is not read.
         for (count = 1; count <= 3; count++)
         {
            currentString >> coordinateValue;
            verticesVector.push_back(coordinateValue);
         }
      }

      // Line has face data.
      else if (line.substr(0, 2) == "f ")
      {
         // Initialize a string from the character after "f " to the end.
         std::istringstream currentString(line.substr(2));

         // Strategy in the following to detect a vertex index within a face line is based on the
         // fact that vertex indices are exactly those that follow a white space. Texture and
         // normal indices are ignored.
         // Moreover, from the third vertex of a face on output one triangle per vertex, that
         // being the next triangle in a fan triangulation of the face about the first vertex.
         previousCharacter = ' ';
         count = 0;
         while (currentString.get(currentCharacter))
         {
            // Stop processing line at comment.
            if ((previousCharacter == '#') || (currentCharacter == '#')) break;

            // Current character is the start of a vertex index.
            if ((previousCharacter == ' ') && (currentCharacter != ' '))
            {
               // Move the string cursor back to just before the vertex index.
               currentString.unget();

               // Read the first vertex index, decrement it so that the index range is from 0, increment vertex counter.
               if (count == 0)
               {
                  currentString >> vertexIndex1;
                  vertexIndex1--;
                  count++;
               }

               // Read the second vertex index, decrement it, increment vertex counter.
               else if (count == 1)
               {
                  currentString >> vertexIndex2;
                  vertexIndex2--;
                  count++;
               }

               // Read the third vertex index, decrement it, increment vertex counter AND output the first triangle.
               else if (count == 2)
               {
                  currentString >> vertexIndex3;
                  vertexIndex3--;
                  count++;
                  facesVector.push_back(vertexIndex1);
                  facesVector.push_back(vertexIndex2);
                  facesVector.push_back(vertexIndex3);
               }

               // From the fourth vertex and on output the next triangle of the fan.
               else
               {
                  vertexIndex2 = vertexIndex3;
                  currentString >> vertexIndex3;
                  vertexIndex3--;
                  facesVector.push_back(vertexIndex1);
                  facesVector.push_back(vertexIndex2);
                  facesVector.push_back(vertexIndex3);
               }

               // Begin the process of detecting the next vertex index just after the vertex index just read.
               currentString.get(previousCharacter);
            }

            // Current character is not the start of a vertex index. Move ahead one character.
            else previousCharacter = currentCharacter;
         }
      }

      // Nothing other than vertex and face data is processed.
      else
      {
      }
   }

   // Close the OBJ file.
   inFile.close();

   qDebug() << "tyt0";
}

[Pl45m4]

@timob256

This is some years old but maybe it helps.

Also found this:
https://github.com/GarageGames/Qt/blob/master/qt-5/qt3d/src/render/io/objloader.cpp